TY - CONF
TI - Understanding of Intraplate Seismicity and Surface Deformation Associated with the August 9th, 2020 Mw 5.1 Earthquake Near Sparta, North Carolina
C2 - 2020///
C3 - Geological Society of America 2020 Meeting
DA - 2020///
ER -
TY - CONF
TI - Surface rupture of the Little River fault in response to the August 9, 2020 Mw 5.1 earthquake near Sparta, North Carolina
C2 - 2020///
C3 - Southern California Earthquake Center Annual Meeting
DA - 2020///
ER -
TY - CONF
TI - Surface deformation associated with the Mw 5.1 Sparta, NC, Earthquake, Late Breaking Session Current Understanding of Intraplate Seismicity and Surface Deformation Associated with the August 9th, 2020 Mw 5.1 Earthquake Near Sparta, North Carolina
C2 - 2020/10//
C3 - Geological Society of America
DA - 2020/10//
ER -
TY -
TI - Recorded Presentation Active Tectonics in SW Portugal - Quaternary deformation analysis in a low tectonic rate area GSA 2020
DA - 2020/10//
PY - 2020/10//
UR - https://www.youtube.com/watch?v=r1WBpeE3hcI&t=6s
ER -
TY - CONF
TI - Preliminary observations of Mw 5.1 Sparta (North Carolina) surface deformation – a first documented Mw 5 instrumental earthquake surface rupture in Eastern USA?
C2 - 2020///
C3 - Southern California Earthquake Center Annual Meeting
DA - 2020///
ER -
TY - CONF
TI - Late Pleistocene and Holocene paleoseismology and deformation rates of the Pleasant Valley Fault (Nevada, USA)
C2 - 2020///
C3 - 10th International INQUA Meeting on Paleoseismology, Active Tectonics and Archeoseismology PATA (online)
DA - 2020///
ER -
TY - CONF
TI - Geomorphic and paleoseismic trenching evidence that the Glen Helen fault has not experienced surface rupture in the past 2000 years, and implications for slip transfer between the San Andreas and San Jacinto fault zones
C2 - 2020///
C3 - Southern California Earthquake Center Annual Meeting
DA - 2020///
ER -
TY - CONF
TI - Active Tectonics in SW Portugal - Quaternary deformation analysis in a low tectonic rate area
C2 - 2020/10//
C3 - Geological Society of America
DA - 2020/10//
ER -
TY - CONF
TI - PALEOCOLOGY OF FOSSIL COMMUNITIES IN PENNSYLVANIAN SHALES OF TEXAS
AU - Recchuiti, Erin M.
AU - University, Western Carolina
AU - Cothren, Hannah R.
AU - Stafford, Emily S.
AU - Forcino, Frank L.
C2 - 2020///
C3 - Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020se-345220
PB - Geological Society of America
ER -
TY - CONF
TI - LITHOLOGIC DIVERSITY WITHIN LUNAR REGOLITH BRECCIA METEORITE NORTHWEST AFRICA 8783: CLASTS 3 AND 6
AU - Utterback, Cecillia
AU - University, Western Carolina
AU - Hall, Madi
AU - Recchuiti, Erin M.
AU - Fagan, Amy L.
C2 - 2020///
C3 - Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020se-344673
PB - Geological Society of America
ER -
TY - CONF
TI - LITHOLOGIC DIVERSITY WITHIN LUNAR REGOLITH BRECCIA METEORITE NORTHWEST AFRICA 8783: CLASTS 2 & 5
AU - Hall, Madi
AU - University, Western Carolina
AU - Recchuiti, Erin M.
AU - Utterback, Cecillia
AU - Fagan, Amy L.
C2 - 2020///
C3 - Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020se-344983
PB - Geological Society of America
ER -
TY - CONF
TI - LITHOLOGIC DIVERSITY WITHIN LUNAR REGOLITH BRECCIA METEORITE NORTHWEST AFRICA 8783: CLASTS 1 AND 7
AU - Recchuiti, Erin M.
AU - University, Western Carolina
AU - Hall, Madi
AU - Utterback, Cecillia
AU - Fagan, Amy L.
C2 - 2020///
C3 - Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020se-344671
PB - Geological Society of America
ER -
TY - JOUR
TI - Inverse modeling of SO2 and NOx emissions over China using multisensor satellite data – Part 1: Formulation and sensitivity analysis
AU - Wang, Yi
AU - Wang, Jun
AU - Xu, Xiaoguang
AU - Henze, Daven K.
AU - Qu, Zhen
AU - Yang, Kai
T2 - Atmospheric Chemistry and Physics
AB - Abstract. SO2 and NO2 observations from the Ozone Mapping and Profiler Suite (OMPS) sensor are used for the first time in conjunction with the GEOS-Chem adjoint model to optimize both SO2 and NOx emission estimates over China for October 2013. Separate and joint (simultaneous) optimizations of SO2 and NO2 emissions are both conducted and compared. Posterior emissions, compared to the prior, yield improvements in simulating columnar SO2 and NO2, in comparison to measurements from the Ozone Monitoring Instrument (OMI) and OMPS. The posterior SO2 and NOx emissions from separate inversions are 748 Gg S and 672 Gg N, which are 36 % and 6 % smaller than prior MIX emissions (valid for 2010), respectively. In spite of the large reduction of SO2 emissions over the North China Plain, the simulated sulfate–nitrate–ammonium aerosol optical depth (AOD) only decrease slightly, which can be attributed to (a) nitrate rather than sulfate as the dominant contributor to AOD and (b) replacement of ammonium sulfate with ammonium nitrate as SO2 emissions are reduced. For joint inversions, both data quality control and the weight given to SO2 relative to NO2 observations can affect the spatial distributions of the posterior emissions. When the latter is properly balanced, the posterior emissions from assimilating OMPS SO2 and NO2 jointly yield a difference of −3 % to 15 % with respect to the separate assimilations for total anthropogenic SO2 emissions and ±2 % for total anthropogenic NOx emissions; but the differences can be up to 100 % for SO2 and 40 % for NO2 in some grid cells. Improvements on SO2 and NO2 simulations from the joint inversions are overall consistent with those from separate inversions. Moreover, the joint assimilations save ∼ 50 % of the computational time compared to assimilating SO2 and NO2 separately in a sequential manner of computation. The sensitivity analysis shows that a perturbation of NH3 to 50 % (20 %) of the prior emission inventory can (a) have a negligible impact on the separate SO2 inversion but can lead to a decrease in posterior SO2 emissions over China by −2.4 % (−7.0 %) in total and up to −9.0 % (−27.7 %) in some grid cells in the joint inversion with NO2 and (b) yield posterior NOx emission decreases over China by −0.7 % (−2.8 %) for the separate NO2 inversion and by −2.7 % (−5.3 %) in total and up to −15.2 % (−29.4 %) in some grid cells for the joint inversion. The large reduction of SO2 between 2010 and 2013, however, only leads to ∼ 10 % decrease in AOD regionally; reducing surface aerosol concentration requires the reduction of emissions of NH3 as well.
DA - 2020/6/5/
PY - 2020/6/5/
DO - 10.5194/acp-20-6631-2020
VL - 20
IS - 11
SP - 6631-6650
UR - http://dx.doi.org/10.5194/acp-20-6631-2020
ER -
TY - JOUR
TI - Intercomparison of Magnitudes and Trends in Anthropogenic Surface Emissions From Bottom‐Up Inventories, Top‐Down Estimates, and Emission Scenarios
AU - Elguindi, Nellie
AU - Granier, C.
AU - Stavrakou, Trisevgeni
AU - Darras, S.
AU - Bauwens, M.
AU - Cao, Hansen
AU - CHEN, CHENG
AU - Gon, Hugo Denier
AU - Dubovik, Oleg
AU - Fu, Tzung-May
AU - HENZE, DAVEN
AU - Jiang, Zhe
AU - Keita, S.
AU - Kuenen, J. J. P.
AU - Kurokawa, J.
AU - Liousse, C.
AU - Miyazaki, Kazuyuki
AU - Jean-Francois, Muller
AU - Qu, Zhen
AU - Solmon, F.
AU - Zheng, B.
T2 - Earth's Future
AB - Abstract This study compares recent CO, NO x , NMVOC, SO 2 , BC, and OC anthropogenic emissions from several state‐of‐the‐art top‐down estimates to global and regional bottom‐up inventories and projections from five Shared Socioeconomic Pathways (SSPs) in several regions. Results show that top‐down emissions derived in several recent studies exhibit similar uncertainty as bottom‐up inventories in some regions for certain species and even less in the case of Chinese CO emissions. In general, the largest discrepancies are found outside of regions such as the United States, Europe, and Japan where the most accurate and detailed information on emissions is available. In some regions such as China, which has recently undergone dynamical economic growth and changes in air quality regulations, the top‐down estimates better capture recent emission trends than global bottom‐up inventories. These results show the potential of top‐down estimates to complement bottom‐up inventories and to aide in the development of emission scenarios, particularly in regions where global inventories lack the necessary up‐to‐date and accurate information regarding regional activity data and emission factors such as Africa and India. Areas of future work aimed at quantifying and reducing uncertainty are also highlighted. A regional comparison of recent CO and NO x trends in the five SSPs indicate that SSP126, a strong pollution control scenario, best represents the trends from the top‐down and regional bottom‐up inventories in the United States, Europe, and China, while SSP460, a low‐pollution control scenario, lies closest to actual trends in West Africa. This analysis can be useful for air quality forecasting and near‐future pollution control/mitigation policy studies.
DA - 2020/8//
PY - 2020/8//
DO - 10.1029/2020ef001520
VL - 8
IS - 8
UR - http://dx.doi.org/10.1029/2020ef001520
ER -
TY - JOUR
TI - Impacts of global NOx inversions on NO2 and ozone simulations
AU - Qu, Zhen
AU - Henze, Daven K.
AU - Cooper, Owen R.
AU - Neu, Jessica L.
T2 - Atmospheric Chemistry and Physics
AB - Abstract. Tropospheric NO2 and ozone simulations have large uncertainties, but their biases, seasonality, and trends can be improved with NO2 assimilations. We perform global top-down estimates of monthly NOx emissions using two Ozone Monitoring Instrument (OMI) NO2 retrievals (NASAv3 and DOMINOv2) from 2005 to 2016 through a hybrid 4D-Var/mass balance inversion. Discrepancy in NO2 retrieval products is a major source of uncertainties in the top-down NOx emission estimates. The different vertical sensitivities in the two NO2 retrievals affect both magnitude and seasonal variations of top-down NOx emissions. The 12-year averages of regional NOx budgets from the NASA posterior emissions are 37 % to 53 % smaller than the DOMINO posterior emissions. Consequently, the DOMINO posterior surface NO2 simulations greatly reduced the negative biases in China (by 15 %) and the US (by 22 %) compared to surface NO2 measurements. Posterior NOx emissions show consistent trends over China, the US, India, and Mexico constrained by the two retrievals. Emission trends are less robust over South America, Australia, western Europe, and Africa, where the two retrievals show less consistency. NO2 trends have more consistent decreases (by 26 %) with the measurements (by 32 %) in the US from 2006 to 2016 when using the NASA posterior emissions. The performance of posterior ozone simulations has spatial heterogeneities from region to region. On a global scale, ozone simulations using NASA-based emissions alleviate the double peak in the prior simulation of global ozone seasonality. The higher abundances of NO2 from the DOMINO posterior simulations increase the global background ozone concentrations and therefore reduce the negative biases more than the NASA posterior simulations using GEOS-Chem v12 at remote sites. Compared to surface ozone measurements, posterior simulations have more consistent magnitude and interannual variations than the prior estimates, but the performance from the NASA-based and DOMINO-based emissions varies across ozone metrics. The limited availability of remote-sensing data and the use of prior NOx diurnal variations hinder improvement of ozone diurnal variations from the assimilation, and therefore have mixed performance on improving different ozone metrics. Additional improvements in posterior NO2 and ozone simulations require more precise and consistent NO2 retrieval products, more accurate diurnal variations of NOx and VOC emissions, and improved simulations of ozone chemistry and depositions.
DA - 2020/11/9/
PY - 2020/11/9/
DO - 10.5194/acp-20-13109-2020
VL - 20
IS - 21
SP - 13109-13130
UR - http://dx.doi.org/10.5194/acp-20-13109-2020
ER -
TY - JOUR
TI - Global methane budget and trend, 2010–2017: complementarity of inverse analyses using in situ (GLOBALVIEWplus CH<sub>4</sub> ObsPack) and satellite (GOSAT) observations
AU - Lu, Xiao
AU - Jacob, Daniel J.
AU - Zhang, Yuzhong
AU - Maasakkers, Joannes
AU - Sulprizio, Melissa P.
AU - Shen, Lu
AU - Qu, Zhen
AU - Scarpelli, Tia R.
AU - Nesser, Hannah
AU - Yantosca, Robert
AU - Sheng, Jianxiong
AU - Andrews, Arlyn
AU - Parker, Robert
AU - Boech, Hartmut
AU - Bloom, A. Anthony
AU - Ma, Shuang
AB - Abstract. We use satellite (GOSAT) and in situ (GLOBALVIEWplus CH4 ObsPack) observations of atmospheric methane in a joint global inversion of methane sources, sinks, and trends for the 2010–2017 period. The inversion is done by analytical solution to the Bayesian optimization problem, yielding closed-form estimates of information content to assess the consistency and complementarity (or redundancy) of the satellite and in situ datasets. We find that GOSAT and in situ observations are to a large extent complementary, with GOSAT providing a stronger overall constraint on the global methane distributions, but in situ observations being more important for northern mid-latitudes and for relaxing global error correlations between methane emissions and the main methane sink (oxidation by OH radicals). The GOSAT observations achieve 212 independent pieces of information (DOFS) for quantifying mean 2010–2017 anthropogenic emissions on 1009 global model grid elements, and a DOFS of 122 for 2010–2017 emission trends. Adding the in situ data increases the DOFS by about 20–30 %, to 262 and 161 respectively for mean emissions and trends. Our joint inversion finds that oil/gas emissions in the US and Canada are underestimated relative to the values reported by these countries to the United Nations Framework Convention on Climate Change (UNFCCC) and used here as prior estimates, while coal emissions in China are overestimated. Wetland emissions in North America are much lower than in the mean WetCHARTs inventory used as prior estimate. Oil/gas emissions in the US increase over the 2010–2017 period but decrease in Canada and Europe. Our joint GOSAT+in situ inversion yields a global methane emission of 551 Tg a−1 averaged over 2010–2017 and a methane lifetime of 11.2 years against oxidation by tropospheric OH (86 % of the methane sink).
DA - 2020/9/17/
PY - 2020/9/17/
DO - 10.5194/acp-2020-775
VL - 9
UR - http://dx.doi.org/10.5194/acp-2020-775
ER -
TY - JOUR
TI - Attribution of the accelerating increase in atmospheric methane during 2010–2018 by inverse analysis of GOSAT observations
AU - Zhang, Yuzhong
AU - Jacob, Daniel J.
AU - Lu, Xiao
AU - Maasakkers, Joannes
AU - Scarpelli, Tia R.
AU - Sheng, Jianxiong
AU - Shen, Lu
AU - Qu, Zhen
AU - Sulprizio, Melissa P.
AU - CHANG, Jinfeng
AU - Bloom, Anthony A.
AU - Ma, Shuang
AU - Worden, John
AU - Parker, Robert
AU - Boesch, Hartmut
AB - Abstract. We conduct a global inverse analysis of 2010–2018 GOSAT satellite observations to better understand the factors controlling atmospheric methane and its accelerating increase over the 2010–2018 period. The inversion optimizes 2010–2018 anthropogenic methane emissions and their trends on a 4º × 5º grid, monthly regional wetland emissions, and annual hemispheric concentrations of tropospheric OH (the main sink of methane) also for individual years. We use an analytical solution to the Bayesian optimization problem that provides closed-form estimates of error covariances and information content for the solution. Our inversion successfully reduces the errors against the independent methane observations from the TCCON network and reproduces the interannual variability of the methane growth rate inferred from NOAA background sites. We find that prior estimates of fuel-related emissions reported by individual countries to the United Nations are too high for China (coal) and Russia (oil/gas), and too low for Venezuela (oil/gas) and the U.S. (oil/gas). We show that the 2010–2018 increase in global methane emissions is mainly driven by tropical wetlands (Amazon and tropical Africa), boreal wetlands (Eurasia), and tropical livestock (South Asia, Africa, Brazil), with no significant trend in oil/gas emissions. While the rise in tropical livestock emissions is consistent with bottom-up estimates of rapidly growing cattle populations, the rise in wetland emissions needs to be better understood. The sustained acceleration of growth rates in 2016–2018 relative to 2010–2013 is mostly from wetlands, while the peak methane growth rates in 2014–2015 are also contributed by low OH concentrations (2014) and high fire emissions (2015). Our best estimate is that OH did not contribute significantly to the 2010–2018 methane trend other than the 2014 spike, though error correlation with global anthropogenic emissions limits confidence in this result.
DA - 2020/9/25/
PY - 2020/9/25/
DO - 10.5194/acp-2020-964
VL - 9
UR - http://dx.doi.org/10.5194/acp-2020-964
ER -
TY - JOUR
TI - Outgoing Near‐Infrared Radiation From Vegetation Scales With Canopy Photosynthesis Across a Spectrum of Function, Structure, Physiological Capacity, and Weather
AU - Baldocchi, Dennis D.
AU - Ryu, Youngryel
AU - Dechant, Benjamin
AU - Eichelmann, Elke
AU - Hemes, Kyle
AU - Ma, Siyan
AU - Sanchez, Camilo Rey
AU - Shortt, Robert
AU - Szutu, Daphne
AU - Valach, Alex
AU - Verfaillie, Joe
AU - Badgley, Grayson
AU - Zeng, Yelu
AU - Berry, Joseph A.
T2 - Journal of Geophysical Research: Biogeosciences
AB - Abstract We test the relationship between canopy photosynthesis and reflected near‐infrared radiation from vegetation across a range of functional (photosynthetic pathway and capacity) and structural conditions (leaf area index, fraction of green and dead leaves, canopy height, reproductive stage, and leaf angle inclination), weather conditions, and years using a network of field sites from across central California. We based our analysis on direct measurements of canopy photosynthesis, with eddy covariance, and measurements of reflected near‐infrared and red radiation from vegetation, with light‐emitting diode sensors. And we interpreted the observed relationships between photosynthesis and reflected near‐infrared radiation using simulations based on the multilayer, biophysical model, CanVeg. Measurements of reflected near‐infrared radiation were highly correlated with measurements of canopy photosynthesis on half‐hourly, daily, seasonal, annual, and decadal time scales across the wide range of function and structure and weather conditions. Slopes of the regression between canopy photosynthesis and reflected near‐infrared radiation were greatest for the fertilized and irrigated C 4 corn crop, intermediate for the C 3 tules on nutrient‐rich organic soil and nitrogen fixing alfalfa, and least for the native annual grasslands and oak savanna on nutrient‐poor, mineral soils. Reflected near‐infrared radiation from vegetation has several advantages over other remotely sensed vegetation indices that are used to infer canopy photosynthesis; it does not saturate at high leaf area indices, it is insensitive to the presence of dead legacy vegetation, the sensors are inexpensive, and the reflectance signal is strong. Hence, information on reflected near‐infrared radiation from vegetation may have utility in monitoring carbon assimilation in carbon sequestration projects or on microsatellites orbiting Earth for precision agriculture applications.
DA - 2020/7//
PY - 2020/7//
DO - 10.1029/2019JG005534
VL - 125
IS - 7
J2 - J. Geophys. Res. Biogeosci.
LA - en
OP -
SN - 2169-8953 2169-8961
UR - http://dx.doi.org/10.1029/2019JG005534
DB - Crossref
ER -
TY - JOUR
TI - Transpiration and evaporation in a Californian oak-grass savanna: Field measurements and partitioning model results
AU - Ma, Siyan
AU - Eichelmann, Elke
AU - Wolf, Sebastian
AU - Rey-Sanchez, Camilo
AU - Baldocchi, Dennis D.
T2 - Agricultural and Forest Meteorology
AB - As the eddy-covariance technique enables intensive measurements of evapotranspiration (ET) at the ecosystem level, the interest in further partitioning ET into two main process-based components transpiration (T) and surface evaporation (E) □ is increasing. Although models for partitioning tower-measured ET have been developed, their reliability for different types of ecosystems still requires extensive validations. From 2001 to 2019, we measured CO2 and H2O vapor fluxes over an oak-grass savanna landscape from three eddy-covariance towers (i.e., one over an oak woodland; the other two over annual grasslands under tree canopy and in open area). Annual ET (± standard deviation) from the oak woodland, understory grassland, and open grassland was 419±85 mm, 167±36 mm, 324±43 mm, respectively. The differences between the above- and below-canopy ET indicated that oak canopy transpiration (Toak) was 281±48 mm year−1, accounting for 67±8% of the total ET of the woodland. The Toak/ET ratio varied in seasons, similar to the pattern of oak's leaf area index but opposite to that of soil moisture. We then tested two ET-partitioning models: Scott's long-term-regression-interception (LTRI) model (Scott and Biederman, 2017) and Zhou's quantile-regression-maximum-slope (QRMS) model (Zhou et al., 2016). Even though we expected that the two models would give divergent results since theiremo working principles, both models captured reasonable magnitudes and seasonal patterns of the T/ET ratio, as suggested by tower measurements. The study confirms that the LTRI and QRMS models are applicable for savanna ecosystems, but some modifications are necessary for tree dominated areas. In combination with field and modeling approaches, this study improves our understanding on the contributions of transpiration and evaporation to total ET from ecosystems with vertical vegetation layers.
DA - 2020/12//
PY - 2020/12//
DO - 10.1016/j.agrformet.2020.108204
VL - 295
SP - 108204
J2 - Agricultural and Forest Meteorology
LA - en
OP -
SN - 0168-1923
UR - http://dx.doi.org/10.1016/j.agrformet.2020.108204
DB - Crossref
ER -
TY - JOUR
TI - Quantifying CH4 concentration spikes above baseline and attributing CH4 sources to hydraulic fracturing activities by continuous monitoring at an off-site tower
AU - Russell, Sarah J.
AU - Vines, Chante’ D.
AU - Bohrer, Gil
AU - Johnson, Derek R.
AU - Villa, Jorge A.
AU - Heltzel, Robert
AU - Rey-Sanchez, Camilo
AU - Matthes, Jaclyn H.
T2 - Atmospheric Environment
AB - Hydraulic fracturing (hydrofracking) for natural gas has increased rapidly in the area of the Marcellus Shale in the last thirty years and estimates of CH4 emissions from hydrofracking operations are still uncertain. Previous studies on CH4 emissions at hydrofracking operations have used bottom-up approaches collected at discrete timepoints or discrete aerial surveys covering a wide spatial area, constraining the temporal scale of inference regarding these emissions. This project monitored atmospheric CH4 concentrations and stable carbon isotopes at a half-hourly temporal resolution from a 20-m tower downwind of a hydrofracking well pad in West Virginia for eighteen months. We collected four months of baseline observations prior to onsite well development to construct an empirical artificial neural-network model of baseline CH4 concentrations. We compared measured CH4 concentrations against the ANN-modeled CH4 baseline to identify CH4 concentration spikes that coincided with different stages of onsite well development, from the baseline period through fracking. CH4 concentration spikes were significantly more frequent than baseline conditions during the vertical drilling and fracking phases of operations. We found that the median magnitude of CH4 concentration spikes during the vertical drilling phase was 316% larger than that of the baseline phase, and the median magnitude of CH4 concentration spikes was 509% larger in the hydraulic stimulation (fracking) stage compared to the baseline phase. We also partitioned the sources of measured CH4 concentrations to biogenic ruminant and geologic shale gas isotopic signatures by measuring 13CH4 gas at high temporal resolution and using a source-partitioning 13CH4 model. The measured median value of half-hourly CH4 concentration spikes attributed to a geologic shale gas isotopic origin was 27% larger than the median CH4 concentration spikes attributed to ruminants, and the maximum half-hourly CH4 concentration spike attributed to shale gas was up to 179% higher than maximum CH4 concentration spike for ruminant-dominated half-hours. This study developed a framework for off-site, single tower measurements to identify CH4 concentration spikes associated with the phases of unconventional natural gas well development in a complex CH4 emissions airshed.
DA - 2020/5//
PY - 2020/5//
DO - 10.1016/j.atmosenv.2020.117452
VL - 228
SP - 117452
J2 - Atmospheric Environment
LA - en
OP -
SN - 1352-2310
UR - http://dx.doi.org/10.1016/j.atmosenv.2020.117452
DB - Crossref
ER -
TY - JOUR
TI - Plant‐mediated methane transport in emergent and floating‐leaved species of a temperate freshwater mineral‐soil wetland
AU - Villa, Jorge A.
AU - Ju, Yang
AU - Stephen, Taylor
AU - Rey‐Sanchez, Camilo
AU - Wrighton, Kelly C.
AU - Bohrer, Gil
T2 - Limnology and Oceanography
AB - Abstract Methane flux from freshwater mineral‐soil (FWMS) wetlands and its variability among sites is largely modulated by plant‐mediated transport. However, plant‐mediated transport processes are rarely resolved in land surface models and are poorly parametrized for plants commonly found in FWMS wetlands. Here, relationships between methane flux and CO 2 uptake, as well as plant conductance of methane were evaluated for three plant species and two characteristic functional types: emergent (narrow‐leaved cattail) and floating‐leaved (American lotus and water lily). We found significant but contrasting correlations between methane flux and CO 2 uptake in cattails ( r 2 = 0.51, slope = −0.16, during morning) and water lily ( r 2 = 0.32, slope = 0.064, after midday). This relationship was not significant in American lotus, showing that stomata regulation of methane fluxes is species‐specific and not generalizable across the floating‐leaved plant functional type. Conductance of methane per leaf area showed distinct seasonal dynamics across species. Conductance was similar among the floating‐leaved species (6.2 × 10 −3 m d −1 in lotus and 7.2 × 10 −3 m d −1 in water lily) and higher than conductance in the emergent species (2.7 × 10 −3 m d −1 ). Our results provide direct observations of plant conductance rates and identify the vegetation parameters (leaf area, stomatal conductance) that modify them. Our results further suggest that models of methane emissions from FWMS should parameterize plant‐mediated transport in different plant functional types, scaled by leaf area and with variable seasonal phenological dynamics, and consider possible species‐specific mechanisms that control methane transport through plants.
DA - 2020/6//
PY - 2020/6//
DO - 10.1002/lno.11467
VL - 65
IS - 7
SP - 1635-1650
J2 - Limnol Oceanogr
LA - en
OP -
SN - 0024-3590 1939-5590
UR - http://dx.doi.org/10.1002/lno.11467
DB - Crossref
ER -
TY - JOUR
TI - Methane emissions reduce the radiative cooling effect of a subtropical estuarine mangrove wetland by half
AU - Liu, Jiangong
AU - Zhou, Yulun
AU - Valach, Alex
AU - Shortt, Robert
AU - Kasak, Kuno
AU - Rey‐Sanchez, Camilo
AU - Hemes, Kyle S.
AU - Baldocchi, Dennis
AU - Lai, Derrick Y. F.
T2 - Global Change Biology
AB - Abstract The role of coastal mangrove wetlands in sequestering atmospheric carbon dioxide (CO 2 ) and mitigating climate change has received increasing attention in recent years. While recent studies have shown that methane (CH 4 ) emissions can potentially offset the carbon burial rates in low‐salinity coastal wetlands, there is hitherto a paucity of direct and year‐round measurements of ecosystem‐scale CH 4 flux (F CH4 ) from mangrove ecosystems. In this study, we examined the temporal variations and biophysical drivers of ecosystem‐scale F CH4 in a subtropical estuarine mangrove wetland based on 3 years of eddy covariance measurements. Our results showed that daily mangrove F CH4 reached a peak of over 0.1 g CH 4 ‐C m −2 day −1 during the summertime owing to a combination of high temperature and low salinity, while the wintertime F CH4 was negligible. In this mangrove, the mean annual CH 4 emission was 11.7 ± 0.4 g CH 4 ‐C m –2 year −1 while the annual net ecosystem CO 2 exchange ranged between −891 and −690 g CO 2 ‐C m −2 year −1 , indicating a net cooling effect on climate over decadal to centurial timescales. Meanwhile, we showed that mangrove F CH4 could offset the negative radiative forcing caused by CO 2 uptake by 52% and 24% over a time horizon of 20 and 100 years, respectively, based on the corresponding sustained‐flux global warming potentials. Moreover, we found that 87% and 69% of the total variance of daily F CH4 could be explained by the random forest machine learning algorithm and traditional linear regression model, respectively, with soil temperature and salinity being the most dominant controls. This study was the first of its kind to characterize ecosystem‐scale F CH4 in a mangrove wetland with long‐term eddy covariance measurements. Our findings implied that future environmental changes such as climate warming and increasing river discharge might increase CH 4 emissions and hence reduce the net radiative cooling effect of estuarine mangrove forests.
DA - 2020/7/15/
PY - 2020/7/15/
DO - 10.1111/gcb.15247
VL - 26
IS - 9
SP - 4998-5016
J2 - Glob Change Biol
LA - en
OP -
SN - 1354-1013 1365-2486
UR - http://dx.doi.org/10.1111/gcb.15247
DB - Crossref
ER -
TY - JOUR
TI - Experimental harvesting of wetland plants to evaluate trade-offs between reducing methane emissions and removing nutrients accumulated to the biomass in constructed wetlands
AU - Kasak, K.
AU - Valach, A.C.
AU - Rey-Sanchez, C.
AU - Kill, K.
AU - Shortt, R.
AU - Liu, J.
AU - Dronova, I.
AU - Mander, Ü.
AU - Szutu, D.
AU - Verfaillie, J.
AU - Baldocchi, D.D.
T2 - Science of The Total Environment
AB - Constructed wetlands built for water treatment often need biomass harvesting to remove nutrients from the system. Usually harvesting is done during the peak growing season to maximize the amount of nutrients removed from the system. This, however, can create huge methane fluxes that escape from plant tissues to the atmosphere. We used manual chambers and eddy covariance measurements to analyze the increase in methane emissions due to the harvesting of two common wetland species, Typha spp. and Schoenoplectus spp., in two climatically different constructed wetlands in Estonia and California. In addition, we determined the biomass nutrient and carbon concentrations from harvested biomass. We found that harvesting during the summer season, e.g. June and August, resulted in a significant release of methane at both sites. At the California site, baseline median methane emissions were 217.6 nmol m−2 s−1, and harvesting resulted in increases to 395.4 nmol m−2 s−1 that decreased to baseline emission within three days. Footprint modeling demonstrated that the emission increases measured by eddy covariance were dominated by contributions from the cut area to the total footprint signal. At the Estonian site, harvesting resulted in methane increases of 15.9 nmol m−2 s−1 to 110.4 nmol m−2 s−1 in August. However, in September and October the emission was significantly lower. Plant biomass analyses showed clear temporal dynamics in terms of nutrient concentration, being highest in summer and lowest in winter. Our experiments indicate that the optimal time for aboveground biomass harvesting is at the end of the growing season before nutrient translocation to belowground plant structures begins coinciding with lowest methane emissions. Therefore, strategic planning of the harvest timing may help reduce greenhouse gas emissions from managed wetlands and thus improve their multi-faceted ecological benefit.
DA - 2020/5//
PY - 2020/5//
DO - 10.1016/j.scitotenv.2020.136960
VL - 715
SP - 136960
J2 - Science of The Total Environment
LA - en
OP -
SN - 0048-9697
UR - http://dx.doi.org/10.1016/j.scitotenv.2020.136960
DB - Crossref
ER -
TY - JOUR
TI - Evidence for rapid trace element alteration of planktic foraminiferal shells from the Panama Basin: Manganese adsorption during vertical transport
AU - Davis, Catherine V.
AU - Benitez-Nelson, Claudia R.
T2 - Marine Micropaleontology
AB - The trace elemental composition of planktic foraminifera shells serves as a proxy for understanding the physical environment in which foraminifera lived, but may also reflect chemical alterations that occur after death. Understanding how foraminiferal geochemistry varies across time, species, and after death is therefore essential for deconvolving ecological from diagenetic information and decoding the environmental signals contained within foraminiferal shells. We analyzed the trace elemental composition (Mg/Ca, Sr/Ca, Ba/Ca, Mn/Ca, and U/Ca) of four species of planktic foraminifera (Globigerina ruber, Neogloboquadrina dutertrei, Globorotalia menardii, and Globorotaloides hexagonus) from moored sediment traps (890, 2590, and 3560 m deep) in the Panama Basin collected over one calendar year (1979–1980). Shells recovered from the shallowest trap demonstrate moderate variability in trace elemental composition, both throughout the time series and between species. Most elemental ratios are not significantly influenced by depth, with the exception of Mn/Ca. Ratios of Mn/Ca are substantially higher in the 3560 m trap versus the 890 m trap, with increases with depth greater in the thin walled species G. ruber and G. hexagonus. Elevated Mn/Ca ratios are frequently noted in fossil foraminifera shells as the result of diagenesis within the sediment. Our results demonstrate the potential for Mn-enrichment of foraminiferal calcite, via Mn adsorption onto the surface of foraminiferal shells, within the water column during sinking and prior to deposition in the sediment.
DA - 2020/5//
PY - 2020/5//
DO - 10.1016/j.marmicro.2020.101872
VL - 157
SP - 101872
J2 - Marine Micropaleontology
LA - en
OP -
SN - 0377-8398
UR - http://dx.doi.org/10.1016/j.marmicro.2020.101872
DB - Crossref
ER -
TY - JOUR
TI - Vertical distribution of planktic foraminifera through an Oxygen Minimum Zone:how assemblages and shell morphology reflect oxygen concentrations
AU - Davis, Catherine V.
AU - Wishner, Karen
AU - Renema, Willem
AU - Hull, Pincelli M.
AB - Abstract. Oxygen-depleted regions of the global ocean are rapidly expanding, with important implications for global biogeochemical cycles. However, our ability to make projections of a future deoxygenated ocean is limited by a lack of empirical data with which to test and constrain the behavior of global climatic and oceanographic models. We use depth-stratified plankton tows to demonstrate that some species of planktic foraminifera are adapted to life in the heart of the pelagic Oxygen Minimum Zone (OMZ). In particular, we identify two species, Globorotaloides hexagonus and Hastigerina parapelagica, living within the Eastern Tropical North Pacific OMZ. The shells of the former are preserved in marine sediments and could be used to trace the extent and intensity of low-oxygen pelagic habitats in the fossil record. Additional morphometric analyses of G. hexagonus show that shells found in the lowest oxygen environments are larger, more porous, less dense, and have more chambers in the final whorl. The association of this species with the OMZ and the apparent plasticity of its shell in response to ambient oxygenation invites the use of G. hexagonus shells in sediment cores as potential proxies for both the presence and intensity of overlying OMZs.
DA - 2020/8//
PY - 2020/8//
DO - 10.5194/bg-2020-280
VL - 8
ER -
TY - JOUR
TI - Extensive morphological variability in asexually produced planktic foraminifera
AU - Davis, Catherine V.
AU - Livsey, Caitlin M.
AU - Palmer, Hannah M.
AU - Hull, Pincelli M.
AU - Thomas, Ellen
AU - Hill, Tessa M.
AU - Benitez-Nelson, Claudia R.
T2 - Science Advances
AB - Marine protists are integral to the structure and function of pelagic ecosystems and marine carbon cycling, with rhizarian biomass alone accounting for more than half of all mesozooplankton in the oligotrophic oceans. Yet, understanding how their environment shapes diversity within species and across taxa is limited by a paucity of observations of heritability and life history. Here, we present observations of asexual reproduction, morphologic plasticity, and ontogeny in the planktic foraminifer Neogloboquadrina pachyderma in laboratory culture. Our results demonstrate that planktic foraminifera reproduce both sexually and asexually and demonstrate extensive phenotypic plasticity in response to nonheritable factors. These two processes fundamentally explain the rapid spatial and temporal response of even imperceptibly low populations of planktic foraminifera to optimal conditions and the diversity and ubiquity of these species across the range of environmental conditions that occur in the ocean.
DA - 2020/7/10/
PY - 2020/7/10/
DO - 10.1126/sciadv.abb8930
VL - 6
IS - 28
SP - eabb8930
J2 - Sci. Adv.
LA - en
OP -
SN - 2375-2548
UR - http://dx.doi.org/10.1126/sciadv.abb8930
DB - Crossref
ER -
TY - JOUR
TI - Sea surface temperature across the Subarctic North Pacific and marginal seas through the past 20,000 years: A paleoceanographic synthesis
AU - Davis, Catherine V.
AU - Myhre, Sarah E.
AU - Deutsch, Curtis
AU - Caissie, Beth
AU - Praetorius, Summer
AU - Borreggine, Marisa
AU - Thunell, Robert
T2 - Quaternary Science Reviews
AB - Deglacial sea surface conditions in the subarctic North Pacific and marginal seas are the subject of increasing interest in paleoceanography. However, a cohesive picture of near-surface oceanography from which to compare inter and intra-regional variability through the last deglaciation is lacking. We present a synthesis of sea surface temperature covering the open North Pacific and its marginal seas, spanning the past 20 ka using proxy records from foraminiferal calcite (δ18O and Mg/Ca) and coccolithophore alkenones (Uk’37). Sea surface temperature proxies tend to be in agreement through the Holocene, though Uk’37 records are often interpreted as warmer than adjacent δ18O or Mg/Ca records during the Last Glacial Maximum and early deglaciation. In the Sea of Okhotsk, Holocene discrepancies between δ18O and Uk’37 may be the result of changes in near-surface stratification. We find that sea-surface warming occurred prior to the onset of the Bølling-Allerød (14.7 ka) and coincident with the onset of the Holocene (11.7 ka) in much of the North Pacific and Bering Sea. Proxy records also show a cold reversal roughly synchronous with the Younger Dryas (12.9–11.7 ka). After the onset of the Holocene, the influence of an intensified warm Kuroshio Current is evident at higher latitudes in the Western Pacific, and an east-west seesaw in sea surface temperature, likely driven by changes in the strength of the North Pacific Gyre, characterizes the open interglacial North Pacific.
DA - 2020/10//
PY - 2020/10//
DO - 10.1016/j.quascirev.2020.106519
VL - 246
SP - 106519
J2 - Quaternary Science Reviews
LA - en
OP -
SN - 0277-3791
UR - http://dx.doi.org/10.1016/j.quascirev.2020.106519
DB - Crossref
ER -
TY - JOUR
TI - Trace Element Heterogeneity Across Individual Planktic Foraminifera from the Modern Cariaco Basin
AU - Davis, Catherine V.
AU - Fehrenbacher, Jennifer S.
AU - Benitez-Nelson, Claudia
AU - Thunell, Robert C.
T2 - Journal of Foraminiferal Research
AB - ABSTRACT The trace element composition of planktic foraminifera shells is influenced by both environmental and biological factors (‘vital effects’). As trace elements in individual foraminifera shells are increasingly used as paleoceanographic tools, understanding how trace element ratios vary between individuals, among species, and in response to high frequency environmental variability is of critical importance. Here, we present a three-year plankton tow record (2010–2012) of individual shell trace element (Mg, Sr, Ba, and Mn) to Ca ratios in the planktic species Globigerina ruber (pink), Orbulina universa, and Globorotalia menardii collected throughout the upper 100 m of Cariaco Basin. Plankton tows were paired with in situ measurements of water column chemistry and hydrography. The Mg/Ca ratio reflects different calcification temperatures in all three species when calculated using species-specific temperature relationships from single-species averages of Mg/Ca. However, individual shell Mg/Ca often results in unrealistic temperate estimates. The Sr/Ca ratios are relatively constant among the four species. Ratios of Mn/Ca and Ba/Ca are highest in G. menardii and are not reflective of elemental concentrations in open waters. The Mn/Ca ratio is elevated in all species during upwelling conditions, and a similar trend is demonstrated in Neogloboquadrina incompta shells from the California margin collected during upwelling periods. Together this suggests that elevated shell Mn/Ca may act as a tracer for upwelling of deeper water masses. Our results emphasize the large degree of trace element variability present among and within species living within a limited depth habitat and the roles of biology, calcification environment, and physical mixing in mediating how trace element geochemistry reflects environmental variability in the surface ocean.
DA - 2020/4/1/
PY - 2020/4/1/
DO - 10.2113/gsjfr.50.2.204
VL - 50
IS - 2
SP - 204-218
UR - http://dx.doi.org/10.2113/gsjfr.50.2.204
ER -
TY - JOUR
TI - The Impacts of Flood, Drought, and Turbidites on Organic Carbon Burial Over the Past 2,000 years in the Santa Barbara Basin, California
AU - Sarno, Caitlyn T.
AU - Benitez‐Nelson, Claudia R.
AU - Ziolkowski, Lori A.
AU - Hendy, Ingrid L.
AU - Davis, Catherine V.
AU - Tappa, Eric J.
AU - Thunell, Robert C.
T2 - Paleoceanography and Paleoclimatology
AB - Abstract Climate conditions and instantaneous depositional events can influence the relative contribution of sediments from terrestrial and marine environments and ultimately the quantity and composition of carbon buried in the sediment record. Here, we analyze the elemental, isotopic, and organic geochemical composition of marine sediments to identify terrestrial and marine sources in sediment horizons associated with droughts, turbidites, and floods in the Santa Barbara Basin (SBB), California, during the last 2,000 years. Stable isotopes (δ 13 C and δ 15 N) indicate that more terrestrial organic carbon (OC) was deposited during floods relative to background sediment, while bulk C to nitrogen (C/N) ratios remained relatively constant (~10). Long‐chain n ‐alkanes (C 27 , C 29 , C 31 , and C 33 ), characteristic of terrestrial OC, dominated all types of sediment deposition but were 4 times more abundant in flood layers. Marine algae (C 15 , C 17 , and C 19 ) and macrophytes (C 21 and C 23 ) were also 2 times higher in flood versus background sediments. Turbidites contained twice the terrestrial n ‐alkanes relative to background sediment. Conversely, drought intervals were only distinguishable from background sediment by their higher proportion of marine algal n ‐alkanes. Combined, our data indicate that 15% of the total OC buried in SBB over the past 2,000 years was deposited during 11 flood events where the sediment was mostly terrestrially derived, and another 12% of deep sediment OC burial was derived from shelf remobilization during six turbidite events. Relative to twentieth century river runoff, our data suggest that floods result in considerable terrestrial OC burial on the continental margins of California.
DA - 2020/7//
PY - 2020/7//
DO - 10.1029/2020pa003849
VL - 35
IS - 7
J2 - Paleoceanography and Paleoclimatology
LA - en
OP -
SN - 2572-4517 2572-4525
UR - http://dx.doi.org/10.1029/2020PA003849
DB - Crossref
ER -
TY - JOUR
TI - Tropospheric ozone radiative forcing uncertainty due to pre-industrial fire and biogenic emissions
AU - Rowlinson, Matthew J.
AU - Rap, Alexandru
AU - Hamilton, Douglas S.
AU - Pope, Richard J.
AU - Hantson, Stijn
AU - Arnold, Stephen R.
AU - Kaplan, Jed O.
AU - Arneth, Almut
AU - Chipperfield, Martyn P.
AU - Forster, Piers M.
AU - Nieradzik, Lars
AB - Abstract. Tropospheric ozone concentrations are sensitive to natural emissions of precursor compounds. In contrast to existing assumptions, recent evidence indicates that terrestrial vegetation emissions in the pre-industrial were larger than in the present-day. We use a chemical transport model and a radiative transfer model to show that revised inventories of pre-industrial fire and biogenic emissions lead to an increase in simulated pre-industrial ozone concentrations, decreasing the estimated pre-industrial to present-day tropospheric ozone radiative forcing of up to 34 % (0.38 W m-2 to 0.25 W m-2). We find that this change is sensitive to employing biomass burning and biogenic emissions inventories based on matching vegetation patterns, as co-location of emission sources enhances the effect on ozone formation. Our forcing estimates are at the lower end of existing uncertainty range estimates (0.2–0.6 W m-22), without accounting for other sources of uncertainty. Thus, future work should focus on reassessing the uncertainty range of tropospheric ozone radiative forcing.
DA - 2020/1/10/
PY - 2020/1/10/
DO - 10.5194/acp-2019-1065
VL - 1
UR - https://doi.org/10.5194/acp-2019-1065
ER -
TY - JOUR
TI - Recent (1980 to 2015) Trends and Variability in Daily‐to‐Interannual Soluble Iron Deposition from Dust, Fire, and Anthropogenic Sources
AU - Hamilton, Douglas S.
AU - Scanza, Rachel A.
AU - Rathod, Sagar D.
AU - Bond, Tami C.
AU - Kok, Jasper F.
AU - Li, Longlei
AU - Matsui, Hitoshi
AU - Mahowald, Natalie M.
T2 - Geophysical Research Letters
AB - Abstract The iron cycle is a key component of the Earth system. Yet how variable the atmospheric flux of soluble (bioaccessible) iron into oceans is, and how this variability is modulated by human activity and a changing climate, is not well known. For the first time, we characterize Satellite Era (1980 to 2015) daily‐to‐interannual modeled soluble iron emission and deposition variability from both pyrogenic (fires and anthropogenic combustion) and dust sources. Statistically significant emission trends exist: dust iron decreases, fire iron slightly increases, and anthropogenic iron increases. A strong temporal variability in deposition to ocean basins is found, and, for most regions, dust iron dominates the absolute deposition magnitude, fire iron is an important contributor to temporal variability, and anthropogenic iron imposes a significant increasing trend. Quantifying soluble iron daily‐to‐interannual deposition variability from all major iron sources, not only dust, will advance quantification of changes in marine biogeochemistry in response to the continuing human perturbation to the Earth System.
DA - 2020/9/16/
PY - 2020/9/16/
DO - 10.1029/2020GL089688
UR - https://doi.org/10.1029/2020GL089688
KW - soluble iron deposition variability
KW - dust iron
KW - fire iron
KW - anthropogenic iron
KW - biogeochemical cycles
ER -
TY - JOUR
TI - Tropospheric ozone radiative forcing uncertainty due to pre-industrial fire and biogenic emissions
AU - Rowlinson, Matthew J.
AU - Rap, Alexandru
AU - Hamilton, Douglas S.
AU - Pope, Richard J.
AU - Hantson, Stijn
AU - Arnold, Steve R.
AU - Kaplan, Jed O.
AU - Arneth, Almut
AU - Chipperfield, Martyn P.
AU - Forster, Piers M.
AU - Nieradzik, Lars
T2 - Atmospheric Chemistry and Physics
AB - Abstract. Tropospheric ozone concentrations are sensitive to natural emissions of precursor compounds. In contrast to existing assumptions, recent evidence indicates that terrestrial vegetation emissions in the pre-industrial era were larger than in the present day. We use a chemical transport model and a radiative transfer model to show that revised inventories of pre-industrial fire and biogenic emissions lead to an increase in simulated pre-industrial ozone concentrations, decreasing the estimated pre-industrial to present-day tropospheric ozone radiative forcing by up to 34 % (0.38 to 0.25 W m−2). We find that this change is sensitive to employing biomass burning and biogenic emissions inventories based on matching vegetation patterns, as the co-location of emission sources enhances the effect on ozone formation. Our forcing estimates are at the lower end of existing uncertainty range estimates (0.2–0.6 W m−2), without accounting for other sources of uncertainty. Thus, future work should focus on reassessing the uncertainty range of tropospheric ozone radiative forcing.
DA - 2020/9/22/
PY - 2020/9/22/
DO - 10.5194/acp-20-10937-2020
UR - https://doi.org/10.5194/acp-20-10937-2020
ER -
TY - JOUR
TI - The IDEEAS Working Group at Cornell University: A New Framework of Collective Leadership for Promoting Justice, Equity, Diversity, and Inclusion in the Geosciences
AU - Devlin, Kelly
AU - Eiden, Elizabeth
AU - Bürgi, Paula
AU - MacQueen, Patricia
AU - Headlam, Carolyn
AU - Brill, Kyle
AU - Carrillo, Carlos
AU - Hamilton, Douglas S
AU - Jiang, Junle
AU - Barcheck, Grace
AU - Hitchcock, Peter
AU - Mahowald, Natalie
AB - Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]The IDEEAS Working Group at Cornell University: A New Framework of Collective Leadership for Promoting Justice, Equity, Diversity, and Inclusion in the GeosciencesAuthorsKellyDevliniDElizabethEidenPaulaBürgiiDPatriciaMacQueeniDCarolynHeadlamKyleBrilliDCarlosCarrilloDouglas SHamiltoniDJunleJiangiDGraceBarcheckiDPeterHitchcockNatalieMahowaldiDSee all authors Kelly DevliniDCorresponding Author• Submitting AuthorCornell UniversityiDhttps://orcid.org/0000-0003-2014-1065view email addressThe email was not providedcopy email addressElizabeth EidenCornell Universityview email addressThe email was not providedcopy email addressPaula BürgiiDCornell UniversityiDhttps://orcid.org/0000-0003-3001-5759view email addressThe email was not providedcopy email addressPatricia MacQueeniDCornell UniversityiDhttps://orcid.org/0000-0001-7692-3416view email addressThe email was not providedcopy email addressCarolyn HeadlamCornell Universityview email addressThe email was not providedcopy email addressKyle BrilliDCornell UniversityiDhttps://orcid.org/0000-0002-1841-0249view email addressThe email was not providedcopy email addressCarlos CarrilloCornell Universityview email addressThe email was not providedcopy email addressDouglas S HamiltoniDCornell UniversityiDhttps://orcid.org/0000-0002-8171-5723view email addressThe email was not providedcopy email addressJunle JiangiDCornell UniversityiDhttps://orcid.org/0000-0002-8796-5846view email addressThe email was not providedcopy email addressGrace BarcheckiDCornell UniversityiDhttps://orcid.org/0000-0002-1773-1577view email addressThe email was not providedcopy email addressPeter HitchcockCornell Universityview email addressThe email was not providedcopy email addressNatalie MahowaldiDCornell UniversityiDhttps://orcid.org/0000-0002-2873-997Xview email addressThe email was not providedcopy email address
DA - 2020/12/18/
PY - 2020/12/18/
DO - 10.1002/essoar.10505326.1
UR - https://doi.org/10.1002/essoar.10505326.1
ER -
TY - JOUR
TI - Supplementary material to "Improved representation of the global dust cycle using observational constraints on dust properties and abundance"
AU - Kok, Jasper F.
AU - Adebiyi, Adeyemi A.
AU - Albani, Samuel
AU - Balkanski, Yves
AU - Checa-Garcia, Ramiro
AU - Chin, Mian
AU - Colarco, Peter R.
AU - Hamilton, Douglas Stephen
AU - Huang, Yue
AU - Ito, Akinori
AU - Klose, Martina
AU - Leung, Danny M.
AU - Li, Longlei
AU - Mahowald, Natalie M.
AU - Miller, Ron L.
AU - Obiso, Vincenzo
AU - García-Pando, Carlos Pérez
AU - Rocha-Lima, Adriana
AU - Wan, Jessica S.
AU - Whicker, Chloe A.
DA - 2020/11/23/
PY - 2020/11/23/
DO - 10.5194/acp-2020-1131-supplement
VL - 11
UR - https://doi.org/10.5194/acp-2020-1131-supplement
ER -
TY - JOUR
TI - Re-assessment of pre-industrial fires in CMIP6 models and the implications for radiative forcing
AU - Carslaw, Ken
AU - Scott, Cat
AU - Yoshioka, Masaru
AU - Hamilton, Douglas
AU - Fiona, O’Connor
AU - Folberth, Gerd
AU - Mulcahy, Jane
AU - Dalvi, Mohit
AU - Balkanski, Yves
AU - Checa-Garcia, Ramiro
AU - Olivie, Dirk
AU - Schulz, Michael
AU - Michou, Martine
AU - Nabat, Pierre
AU - Nieradzik, Lars
AU - Noije, Twan
AU - Bergman, Tommi
AB - <p>Assessment of anthropogenic radiative forcing requires a robust understanding of the composition of the pre-industrial baseline atmosphere from which calculations are made</p><p>It is often assumed that fire activity and the associated aerosol emissions were lower in the pre-industrial period than in the present day. However, some lines of evidence suggest that fire activity may have halved since the pre-industrial period.&#160;</p><p>Here we compare the simulated ratio of pre-industrial (c.1750CE and c.1850CE) to present-day black carbon surface concentrations in five ESMs (CNRM-ESM2-1, EC-Earth3, IPSL-CM6, NorESM1.2, UKESM1), using historical fire emissions from the Sixth Coupled Model Intercomparison Project (CMIP6), to the ratio in Northern Hemisphere ice-core records.&#160;</p><p>We find that when forced with CMIP6 fire emissions all ESMs overestimate the present-day to pre-industrial black carbon ratio. This is consistent with previous studies and suggests that the contribution of fire to the composition of the pre-industrial atmosphere may be too low. If the contrast between the pre-industrial and present-day atmospheres in these models is too great, they are likely to overestimate the strength of the anthropogenic aerosol radiative forcing.&#160;&#160;</p><p>We extend our analysis to include additional ESMs providing historical simulations for CMIP6, as included in the IPCC&#8217;s Sixth Assessment Report.</p><p>&#160;</p>
DA - 2020/3/23/
PY - 2020/3/23/
DO - 10.5194/egusphere-egu2020-18190
VL - 3
UR - https://doi.org/10.5194/egusphere-egu2020-18190
ER -
TY - JOUR
TI - A Mineralogy‐Based Anthropogenic Combustion‐Iron Emission Inventory
AU - Rathod, S. D.
AU - Hamilton, D. S.
AU - Mahowald, N. M.
AU - Klimont, Z.
AU - Corbett, J. J.
AU - Bond, T. C.
T2 - Journal of Geophysical Research: Atmospheres
AB - Abstract Atmospheric supply of iron can modulate ocean biogeochemistry, due to its key role in global nitrogen and carbon cycles. Current estimates predict up to 20% of global ocean net primary productivity depends on an atmospheric iron source. Using a technology‐based methodology, we revise total and soluble anthropogenic iron emissions and resolve iron into its mineral components, which allows modeling mineral‐specific atmospheric reactions. We compare different methodologies for representing anthropogenic iron solubility: measured in mild and strong leaches and estimated using a mineralogy basis and identify the emissions that are most affected by such assumptions. The inclusion of metal smelting as an iron source increases iron emissions by up to 10 times higher in the fine aerosol fraction (smaller than 1 μm) than most previous inventories. Different solubility assumptions alter anthropogenic soluble iron emissions and deposition by a factor of 20 and 10, respectively. Using solubilities measured in mild leaches and calculated by mineralogy give 20–30 Gg/yr anthropogenic emissions and 40–50 Gg/yr deposition, while those measured in strong leaches give 80–440 Gg/yr emissions and 200–450 Gg/yr deposition. This range of anthropogenic soluble iron deposition leads to global soluble iron deposition of 1,900–2,300 Gg/yr when dust, wildfires, and atmospheric processing are included, indicating such assumptions can affect global soluble iron supply by about 30%. In regions where marine primary productivity is iron limited, anthropogenic combustion‐iron contributes up to half of the atmospheric soluble iron flux to the North Pacific Ocean but supplies less than 5% to the Southern Ocean.
DA - 2020/9/16/
PY - 2020/9/16/
DO - 10.1029/2019JD032114
VL - 125
IS - 17
UR - https://doi.org/10.1029/2019JD032114
KW - anthropogenic
KW - iron
KW - biogeochemistry
KW - mineralogy
KW - solubility
KW - emissions
ER -
TY - JOUR
TI - Impact of Changes to the Atmospheric Soluble Iron Deposition Flux on Ocean Biogeochemical Cycles in the Anthropocene
AU - Hamilton, Douglas S.
AU - Moore, J. Keith
AU - Arneth, Almut
AU - Bond, Tami C.
AU - Carslaw, Ken S.
AU - Hantson, Stijn
AU - Ito, Akinori
AU - Kaplan, Jed O.
AU - Lindsay, Keith
AU - Nieradzik, Lars
AU - Rathod, Sagar D.
AU - Scanza, Rachel A.
AU - Mahowald, Natalie M.
T2 - Global Biogeochemical Cycles
AB - Abstract Iron can be a growth‐limiting nutrient for phytoplankton, modifying rates of net primary production, nitrogen fixation, and carbon export ‐ highlighting the importance of new iron inputs from the atmosphere. The bioavailable iron fraction depends on the emission source and the dissolution during transport. The impacts of anthropogenic combustion and land use change on emissions from industrial, domestic, shipping, desert, and wildfire sources suggest that Northern Hemisphere soluble iron deposition has likely been enhanced between 2% and 68% over the Industrial Era. If policy and climate follow the intermediate Representative Concentration Pathway 4.5 trajectory, then results suggest that Southern Ocean (>30°S) soluble iron deposition would be enhanced between 63% and 95% by 2100. Marine net primary productivity and carbon export within the open ocean are most sensitive to changes in soluble iron deposition in the Southern Hemisphere; this is predominantly driven by fire rather than dust iron sources. Changes in iron deposition cause large perturbations to the marine nitrogen cycle, up to 70% increase in denitrification and 15% increase in nitrogen fixation, but only modestly impacts the carbon cycle and atmospheric CO 2 concentrations (1–3 ppm). Regionally, primary productivity increases due to increased iron deposition are often compensated by offsetting decreases downstream corresponding to equivalent changes in the rate of phytoplankton macronutrient uptake, particularly in the equatorial Pacific. These effects are weaker in the Southern Ocean, suggesting that changes in iron deposition in this region dominates the global carbon cycle and climate response.
DA - 2020/3//
PY - 2020/3//
DO - 10.1029/2019GB006448
UR - https://doi.org/10.1029/2019GB006448
KW - biogeochemistry
KW - iron cycle
KW - carbon cycle
KW - nitrogen cycle
KW - marine net primary productivity
ER -
TY - JOUR
TI - Improved representation of the global dust cycle using observational constraints on dust properties and abundance
AU - Kok, Jasper F.
AU - Adebiyi, Adeyemi A.
AU - Albani, Samuel
AU - Balkanski, Yves
AU - Checa-Garcia, Ramiro
AU - Chin, Mian
AU - Colarco, Peter R.
AU - Hamilton, Douglas Stephen
AU - Huang, Yue
AU - Ito, Akinori
AU - Klose, Martina
AU - Leung, Danny M.
AU - Li, Longlei
AU - Mahowald, Natalie M.
AU - Miller, Ron L.
AU - Obiso, Vincenzo
AU - García-Pando, Carlos Pérez
AU - Rocha-Lima, Adriana
AU - Wan, Jessica S.
AU - Whicker, Chloe A.
AB - Abstract. Even though desert dust is the most abundant aerosol by mass in Earth's atmosphere, atmospheric models struggle to accurately represent its spatial and temporal distribution. These model errors are partially caused by fundamental difficulties in simulating dust emission in coarse-resolution models and in accurately representing dust microphysical properties. Here we mitigate these problems by developing a new methodology that yields an improved representation of the global dust cycle. We present an analytical framework that uses inverse modeling to integrate an ensemble of global model simulations with observational constraints on the dust size distribution, extinction efficiency, and regional dust aerosol optical depth. We then compare the inverse model results against independent measurements of dust surface concentration and deposition flux and find that errors are reduced by approximately a factor of two relative to current model simulations of the Northern Hemisphere dust cycle. The inverse model results show smaller improvements in the less dusty Southern Hemisphere, most likely because both the model simulations and the observational constraints used in the inverse model are less accurate. On a global basis, we find that the emission flux of dust with geometric diameter up to 20 μm (PM20) is approximately 5,000 Tg/year, which is greater than most models account for. This larger PM20 dust flux is needed to match observational constraints showing a large atmospheric loading of coarse dust. We obtain gridded data sets of dust emission, vertically integrated loading, dust aerosol optical depth, (surface) concentration, and wet and dry deposition fluxes that are resolved by season and particle size. As our results indicate that this data set is more accurate than current model simulations and the MERRA-2 dust reanalysis product, it can be used to improve quantifications of dust impacts on the Earth system.
DA - 2020/11/23/
PY - 2020/11/23/
DO - 10.5194/acp-2020-1131
VL - 11
UR - https://doi.org/10.5194/acp-2020-1131
ER -
TY - JOUR
TI - Supplementary material to "Quantifying the range of the dust direct radiative effect due to source mineralogy uncertainty"
AU - Li, Longlei
AU - Mahowald, Natalie M.
AU - Miller, Ron L.
AU - García-Pando, Carlos Pérez
AU - Klose, Martina
AU - Hamilton, Douglas S.
AU - Ageitos, Maria Gonçalves
AU - Ginoux, Paul
AU - Balkanski, Yves
AU - Green, Robert O.
AU - Kalashnikova, Olga
AU - Kok, Jasper F.
AU - Obiso, Vincenzo
AU - Paynter, David
AU - Thompson, David R.
DA - 2020/9/15/
PY - 2020/9/15/
DO - 10.5194/acp-2020-547-supplement
VL - 9
UR - https://doi.org/10.5194/acp-2020-547-supplement
ER -
TY - JOUR
TI - Quantifying the range of the dust direct radiative effect due to source mineralogy uncertainty
AU - Li, Longlei
AU - Mahowald, Natalie M.
AU - Miller, Ron L.
AU - García-Pando, Carlos Pérez
AU - Klose, Martina
AU - Hamilton, Douglas S.
AU - Ageitos, Maria Gonçalves
AU - Ginoux, Paul
AU - Balkanski, Yves
AU - Green, Robert O.
AU - Kalashnikova, Olga
AU - Kok, Jasper F.
AU - Obiso, Vincenzo
AU - Paynter, David
AU - Thompson, David R.
AB - Abstract. The large uncertainty in mineral dust direct radiative effect (DRE) hinders projections of future climate change due to anthropogenic activity. Resolving modelled dust mineral-speciation allows for spatially and temporally varying refractive indices consistent with dust aerosol composition. Here, for the first time, we quantify the range in dust DRE at the top of the atmosphere (TOA) due to current uncertainties in the surface soil mineralogical content using a dust mineral-resolving climate model. We propagate observed uncertainties in soil mineral abundances from two soil mineralogy atlases along with the optical properties of each mineral into the DRE and compare the resultant range with other sources of uncertainty across six climate models. The shortwave DRE responses region-specifically to the dust burden depending on the mineral speciation and underlying shortwave surface albedo; positively when the regionally averaged annual surface albedo is larger than 0.28, and negatively otherwise. Among all minerals examined, the shortwave TOA DRE and single scattering albedo at the 0.44–0.63 µm band are most sensitive to the fractional contribution of iron oxides to the total dust composition. The global net (shortwave plus longwave) TOA DRE is estimated to be within −0.23 to +0.35 W m−2. Approximately 97 % of this range relates to uncertainty in the soil abundance of iron oxides. Representing iron-oxide with solely hematite optical properties leads to an overestimation of shortwave DRE by +0.1 W m−2 at the TOA, as goethite is not as absorbing as hematite in the shortwave spectrum range. Our study highlights the importance of iron oxides to the shortwave DRE: they have a disproportionally large impact on climate considering their small atmospheric mineral mass fractional burden (~2 %). An improved description of iron oxides, such as those planned in the Earth Surface Mineral Dust Source Investigation (EMIT), is thus essential for more accurate estimates of the dust DRE.
DA - 2020/9/15/
PY - 2020/9/15/
DO - 10.5194/acp-2020-547
VL - 9
UR - https://doi.org/10.5194/acp-2020-547
ER -
TY - JOUR
TI - Underestimated Role of Fires in Providing Nutrients for Biogeochemical Cycles
AU - Hamilton, Douglas
AU - Barkley, Anne
AU - Moore, J. Keith
AU - Arneth, Almut
AU - Bond, Tami
AU - Carslaw, Kenneth
AU - Gaston, Cassandra
AU - Hantson, Stijn
AU - Ito, Akinori
AU - Kaplan, Jed
AU - Lindsay, Keith
AU - Nieradzik, Lars
AU - Prospero, Joseph
AU - Rathod, Sagar
AU - Scanza, Rachel
AU - Mahowald, Natalie
AB - <p>Fire regimes respond to both climate and human land management practice changes, in turn modifying land cover distributions, surface albedo, carbon storage, and emissions. Much attention has recently been given to the health and climate impacts of fires, but fires are also an important source of nutrients, such as iron and phosphorus, to both land and ocean biospheres. Fires therefore create important feedbacks within the Earth system. Here we discuss recent developments showing how fires are a previously underestimated source of limiting nutrients, providing up to half the annual deposited amount of soluble iron and soluble phosphorus to southern oceans and the Amazon, respectively. Fire can therefore stimulate ocean productivity by providing long range transport of essential nutrients, released from the vegetation burned and entrained with dust from the surrounding environment, to remote regions. We considered the impact of human activity on soluble iron deposition for the past (c.1750 CE), present (c.2010 CE), and future (c.2100 CE). We find that the global carbon cycle and climate response is dominated by changes to primary productivity within the Southern Ocean (>30&#186;S) and that the carbon export efficiency (gram of carbon sequestered per gram of soluble iron added) for this region is 43% larger when altering fire emissions compared to altering dust emissions. Results suggest that modelling past and future changes in biogeochemical cycles should incorporate information on how fires, and the nutrients carried within their plumes, respond to changes in climate.</p>
DA - 2020/3/23/
PY - 2020/3/23/
DO - 10.5194/egusphere-egu2020-10650
VL - 3
UR - https://doi.org/10.5194/egusphere-egu2020-10650
ER -
TY - MGZN
TI - The global sink of available potential energy by mesoscale air-sea interaction
AU - Bishop, S.
AU - Guo, Y.
AU - Bryan, F.
AU - Small, J.
T2 - US CLIVAR Variations
DA - 2020///
PY - 2020///
DO - 10.5065/g8w0-fy32
VL - 18
SP - 13–16
UR - https://doi.org/10.5065/g8w0-fy32
ER -
TY - CONF
TI - Interannual variability of observed surface divergent meridional eddy heat fluxes in the Kuroshio Extension and Gulf Stream
C2 - 2020/2//
C3 - Ocean Sciences Meeting 2020
DA - 2020/2//
UR - https://agu.confex.com/agu/osm20/preliminaryview.cgi/Paper655339.html
ER -
TY - BOOK
TI - North Carolina Climate Science Report
AU - Kunkel, K.E.
AU - Easterling, D.R.
AU - Ballinger, A.
AU - Bililign, S.
AU - Champion, S.M.
AU - Corbett, D.R.
AU - Dello, K.D.
AU - Dissen, J.
AU - Lackmann, G.M.
AU - Luettich, R. A., Jr.
AU - Perry, L.B.
AU - Robinson, W.A.
AU - Stevens, L.E.
AU - Stewart, B.C.
AU - Terando, A.J.
DA - 2020///
PY - 2020///
SP - 223
PB - North Carolina Institute for Climate Studies
ER -
TY - CHAP
TI - Gravity Never Sleeps
AU - Wegmann, K.W.
T2 - The Good Earth: Introduction to Earth Science
A2 - McConnell, D.A.
A2 - Steer, D.
A2 - Knight, C.
A2 - Owens, K.
PY - 2020///
ET - Fifth
SP - 270–271
PB - McGraw Hill
ER -
TY - CONF
TI - HazMapper: A Flexible Geospatial Mapping App for Natural Hazards
AU - Scheip, C.M.
AU - Wegmann, K.W.
T2 - Virtual Geo For Good Summit
C2 - 2020///
C3 - Virtual Geo For Good Summit
DA - 2020///
PY - 2020///
PB - Virtual Geo For Good Summit
UR - http://go.ncsu.edu/amozfhs
ER -
TY - CONF
TI - The role of subsurface volatiles in the formational history of Noctis Labyrinthus, Mars
AU - Kling, C.L.
AU - Byrne, P.K.
AU - Wegmann, K.W.
C2 - 2020///
C3 - Lunar and Planetary Science Conference
DA - 2020///
VL - 51
ER -
TY - RPRT
TI - Geologic Map of the Mesa Lakes Quadrangle, Mesa and Delta Counties, Colorado
AU - Chesnutt, J.M.
AU - Wegmann, K.W.
AU - Pawl, T.A.
AU - White, J.L.
AU - Cole, R.D.
AU - Bernier, C.M.
AU - Byrne, P.K.
A3 - Colorado Geological Survey
DA - 2020///
PY - 2020///
M1 - OF-19-08
PB - Colorado Geological Survey
SN - OF-19-08
UR - https://coloradogeologicalsurvey.org/publications/geologic-map-mesa-lakes-quadrangle-mesa-delta-colorado/.
ER -
TY - JOUR
TI - Evaluation of the HazMapper Google Earth Engine application for coseismic landslide mapping using the Mw7.8 2016 Kaikōura, New Zealand earthquake as a case study
AU - Wegmann, K.W.
AU - Scheip, C.M.
T2 - Geological Society of America Abstracts with Programs
DA - 2020///
PY - 2020///
DO - 10.1130/abs/2020AM-359135
VL - 52
IS - 6
ER -
TY - CONF
TI - Revisiting the source mechanism of the AD 365 Earthquake Crete, Greece, and Implications for Eastern Mediterranean Tectonics
AU - Gallen, S.F.
AU - Ott, R.
AU - Wegmann, K.W.
AU - Pazzaglia, F.J.
AU - Brandon, M.T.
AU - Ueda, K.
AU - Fassoulas, C.
C2 - 2020///
C3 - Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020AM-352299
VL - 52
M1 - 6
ER -
TY - CONF
TI - Surface deformation associated with the Mw 5.1 Sparta, NC Earthquake
AU - Figueiredo, P.M.
AU - Owen, L.A.
AU - Hill, J.S.
AU - Merschat, A.J.
AU - Scheip, C.M.
AU - Stewart, K.
AU - Carter, M.W.
AU - Wooten, R.M.
AU - Wegmann, K.W.
AU - Bohnenstiehl, D.R.
AU - Cattanach, B.L.
AU - Douglas, T.J.
AU - Witt, A.
AU - Szymanski, E.
C2 - 2020///
C3 - Earthquake: Geological Society of America Abstracts with Programs
DA - 2020///
DO - 10.1130/abs/2020am-361234
VL - 52
M1 - 6
ER -
TY - JOUR
TI - Direct observations of a Mt Everest snowstorm from the world's highest surface‐based radar observations
AU - Perry, L. Baker
AU - Yuter, Sandra E.
AU - Matthews, Tom
AU - Wagnon, Patrick
AU - Khadka, Arbindra
AU - Aryal, Deepak
AU - Shrestha, Dibas
AU - Tait, Alex
AU - Miller, Matthew A.
AU - O'Neill, Alex
AU - Rhodes, Spencer R.
AU - Koch, Inka
AU - Sherpa, Tenzing G.
AU - Tuladhar, Subash
AU - Baidya, Saraju K.
AU - Elvin, Sandra
AU - Elmore, Aurora C.
AU - Gajurel, Ananta
AU - Mayewski, Paul A.
T2 - Weather
AB - Ama Dablam (6812m) in the Khumbu (Everest) region as storm clouds build. (Photo credit: L.B. Perry/National Geographic.) In April and May 2019, National Geographic and Rolex's Perpetual Planet Expedition to Mt Everest (hereafter 2019 Everest Expedition) undertook the most comprehensive science expedition to the Khumbu (Mt Everest) region and included teams of scientists investigating a range of topics, including glacier change, upward shifts in ecosystems, black carbon deposition on glacier surfaces and snow/ice/water chemistry (Mayewski et al., 2020). As the highest mountain on Earth and the heart of the Himalayan water tower supplying water to hundreds of millions of people (Pritchard, 2019; Immerzeel et al., 2020), the rate and impacts of climate change on Mt Everest (known in Nepal and China as Sagarmatha and Qomolangma, respectively) are of tremendous symbolic and practical significance. Weather conditions on Mt Everest are also a key component of climber safety (Moore and Semple, 2004, 2006; Moore et al., 2010). The extreme environment has challenged data collection and limited past insights. For example, prior to the 2019 Everest Expedition, which installed five automatic weather stations, including the two highest in the world (Matthews et al., 2020), direct weather observations were absent from the upper 3500m of the mountain, despite the recognition that data from these elevations can improve understanding of the Himalayan hydrological cycle and improve monitoring of upper-atmosphere winds. Other regional networks are available, although sparse (Sherpa et al., 2017; Litt et al., 2019), including those operated by the Institute for Development Research (France) and Tribhuvan University (e.g. the Mera Peak station, at 6400m asl, is located 30 km south of Mt Everest). Process insights into hydrological cycling were also sought through deployment of the highest elevation vertically pointing 24GHz Micro Rain Radar (Peters et al., 2005) at 5280m asl at Nepal's Everest Base Camp. This paper details the first continuous observations of the vertical structure of a snowstorm in the Khumbu region on 17 April 2019 (Figure 1). Snow began falling at ~1200 utc on 16 April 2019 and continued through 1700 utc 17 April 2019 in association with a 500hPa trough upstream over northern India with moist southwest flow (not shown). The team arrived at the Everest Base Camp at approximately 0600 utc 17 April 2019 and immediately deployed the Micro Rain Radar (Figure 2), a manual precipitation gauge and a snow board in anticipation of additional snowfall. We recorded 9.2mm liquid-equivalent precipitation (9.5cm snowfall) from a core sample collected on a snow board ending at 1800 utc 17 April 2019 at the Everest Base Camp, which does not include snowfall from the previous day. The nearby Institute for Development Research and Tribhuvan University weather stations reported liquid-equivalent precipitation (corrected for undercatch using available wind speed data following Wagnon et al., 2009) of 10.7mm at Pyramid (5050m asl and ~8km southwest) and 5.1mm at Pheriche (4240m asl and ~13km south-southwest) ending at 1800 utc 17 April 2019. Further down valley, our recently installed weather station at Phortse (3810m asl and ~20km southwest: Matthews et al., 2020) that includes a double-alter shielded weighing precipitation gauge recorded 7.0mm precipitation during the same time period. Available surface observations of wind speed and direction during the storm showed channelled upslope flow of ~2–6ms−1 through the valleys during the day, a common occurrence in the Khumbu region (Bollasina et al., 2002; Bonasoni et al., 2010). Micro Rain Radar time–height profiles of radar reflectivity, spectral width (a proxy for turbulence) and Doppler velocity indicate two main episodes of snow on 17 April 2019 (Figure 3). The observed precipitation and velocity structures are similar to those observed by the Micro Rain Radar in snowstorms in other mountainous areas, including Boone, NC and Alta, UT in the USA (Keighton et al., 2009; Garrett et al., 2015) and the tropical Andes of Peru and Bolivia (Endries et al., 2018). Surface visual observations indicated that most of the snow fell as a mixture of graupel and aggregates that included particles with light to moderate riming. Pristine ice crystals were not observed at the surface. A higher percentage of graupel was noted close to 0800 utc. After a few minutes of snow at 0700 utc, a longer period of more intense snow fell from 0750 utc to 1110 utc, and a second period of snow fell from 1300 utc to 1517 utc. The closest weather station recording at the time was Changri Nup (located on a debris-free glacier at 5387m asl and ~7km west-southwest), where air temperature ranged from −3°C to −7°C, and relative humidity was between 80% and 90% during the snowfall. Echo tops reached as high as 4500m above ground level (9780m asl), and most of the echo was within 3000m of ground level or between 5280 and 8280m asl. Weather radar detects precipitation-sized particles >0.2mm in diameter, so the echo top is usually lower than the cloud top (which may consist of cloud droplets <0.2mm). The relationships among radar reflectivity, spectral width and Doppler velocity were variable throughout the snow event (Figure 3). Radar reflectivity is roughly proportional to log10(mass3) in snow and is a time-integrated quantity representing snow particles that formed at different times and locations but ended up in the same volume of air. Reflectivity values ranged from the minimum detectable value of 0dBZ to 25dBZ. Higher spectral width (>1ms−1) is an indicator of greater turbulence (e.g. 1030 utc to 1045 utc) and favourable locations for riming (Garrett et al., 2015). Both upward and downward motions were evident in Doppler velocity as the storm passed over the Everest Base Camp. Measured Doppler velocity is the sum of the vertical air motions and precipitation fall speed. Fall speeds for aggregates and graupel are typically ~1ms−1 (Garrett and Yuter, 2014). The upward (negative) values of Doppler velocity indicate updrafts up to 2ms−1 and localized pockets of instability. Pockets of upward air motions are likely locations of precipitable snow mass growth within the storm, and many of these were near the echo top. Downward (positive) values of Doppler velocity are the result of a combination of downward air motions and downward fall speeds. The higher downward Doppler velocity values sometimes occurred with high reflectivities (e.g. 0800 utc and 0840 utc) and sometimes did not (e.g. 0856 utc to 0918 utc). A power surge at the Everest Base Camp the following day damaged the Micro Rain Radar and prevented additional measurements during the 2019 Everest Expedition. At times, the observed snowstorm extended higher (9780m asl) than the elevation of Mt Everest (8850m asl per updated guidance from National Geographic) suggesting that new snow accumulation on the summit was possible, and cloud immersion was likely. However, most of the time, snowfall was confined to altitudes below the summit. The radar echo contained both upward and downward motions, as well as episodes of higher spectral width indicative of turbulence and environments favourable for riming. These unique vertically pointing radar measurements represent the highest altitude snowstorm ever directly measured from the surface. Although there are lower air pressures at the Everest Base Camp (~530hPa) compared to mountain snowstorms at lower elevations, the structure of the storm is not noticeably different; typical snowstorm structures and their heights above ground level are instead displaced higher relative to sea level. Observations of this single event suggest that satellite-based remote sensing of snowstorms can utilise assumptions of similar structures across a range of mountain elevations. This research was conducted in partnership with the National Geographic Society, Rolex and faculty and students of Tribhuvan University, with approval from all relevant agencies of the Government of Nepal. We thank the communities of the Khumbu Region, our expedition support team, Shangri-La Nepal Trek, Pete Athans and Conrad Anker. We are grateful for Sam Guilford's assistance in preparing Figure 1 and Toby Peele's assistance in preparing Figure 3. Additional funding supporting this research was provided by the National Science Foundation through Grants AGS-1347179 (Perry) and AGS-1905736 (Yuter, Miller, and Rhodes). Changri Nup, Pyramid and Pheriche stations have been funded by the French Service d'Observation GLACIOCLIM (part of IR OZCAR) and by a grant from Labex OSUG@2020 (Investissements d'avenir – ANR10 LABX56) and have been operated with the support of the JEAI HIMALICE and the Ev-K2-CNR Project in collaboration with the Nepal Academy of Science and Technology and Tribhuvan University. We are grateful for the helpful feedback from G.W.K. Moore and an anonymous reviewer.
DA - 2020/10//
PY - 2020/10//
DO - 10.1002/wea.3854
VL - 76
IS - 2
SP - 57-59
ER -
TY - CONF
TI - Investigating hurricane-induced compound flooding and sediment dispersal using coupled hydrology and ocean models
AU - Xue, Z.G.
AU - Bao, D.
AU - Yin, D.
AU - He, R.
AU - Zambon, J.B.
AU - Moulton, M.
AU - Warner, J.C.
AU - Dafne, Z.
AU - Gochis, D.
AU - Yu, W.
T2 - American Geophysical Union Fall Meeting
C2 - 2020///
CY - (Virtual)
DA - 2020///
PY - 2020/12/7/
ER -
TY - CONF
TI - AUTOMATED LAND COVER CHANGE DETECTION through RAPID UAS UPDATES of DIGITAL SURFACE MODELS
AU - White, C.T.
AU - Petrasova, A.
AU - Reckling, W.
AU - Mitasova, H.
AB - Abstract. Up to date geospatial data provide the foundation for the development of smart and connected communities. While high-resolution 2D imagery is becoming widely available at less than monthly intervals and several infrastructure layers (e.g., roads, building footprints) are updated on a continuous basis, digital surface models (DSM) are generated less frequently and become quickly obsolete in rapidly developing regions. We present a methodology for continuous and efficient updates of DSM based on automated change detection from high-resolution satellite imagery that is used to develop UAS deployment plan, data acquisition, and DSM generation for targeted areas. The resulting UAS-derived DSM is then seamlessly fused with existing (usually lidar-based) DSM. We demonstrate our methodology in a rapidly developing watershed in the Triangle Region, North Carolina. The change detection maps were created using pixel-based classification methods on monthly composite data generated from PlanetScope satellites (3m resolution) as input for UAS flight planning, data acquisition, and processing. In future work a GRASS GIS script using a moving window resampling process will create flight areas to resample the change detection output into 10 acres flight areas for the UAS flight planning software, and a plugin for WebODM will be developed using GRASS GIS to enable seamless updates to centralized repositories of DSM.
C2 - 2020///
C3 - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives
DA - 2020///
DO - 10.5194/isprs-archives-XLII-3-W11-155-2020
VL - 42
SP - 155-159
M1 - 3/W11
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081623143&partnerID=MN8TOARS
ER -
TY - CONF
TI - Integrating WRF Hydro into the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system: application to Hurricane Florence (2018)
AU - Warner, J.C.
AU - Zambon, J.B.
AU - He, R.
AU - Dafne, Z.
AU - Hegermiller, C.
T2 - American Geophysical Union (AGU) Ocean Sciences Meeting
C2 - 2020///
CY - San Diego, California
DA - 2020///
PY - 2020/2/16/
ER -
TY - CONF
TI - Atmospheric forcing of the Hatteras coastal ocean during PEACH
AU - Bane, J.
AU - Seim, H.
AU - Haines, S.
AU - He, R.
AU - Zambon, J.B.
AU - Gawarkiewicz, G.
T2 - American Geophysical Union (AGU) Ocean Sciences Meeting
C2 - 2020///
CY - San Diego, California
DA - 2020///
PY - 2020/2/16/
ER -
TY - CONF
TI - Ocean responses to major hurricanes during PEACH: a model synthesis study
AU - He, R.
AU - Mao, S.
AU - Zambon, J.B.
AU - Bane, J.
AU - Gawarkiewicz, G.
AU - Todd, R.E.
AU - Seim, H.
AU - Edwards, C.
AU - Andres, M.
AU - Savidge, D.
T2 - American Geophysical Union (AGU) Ocean Sciences Meeting
C2 - 2020///
CY - San Diego, California
DA - 2020///
PY - 2020/2/16/
ER -
TY - CONF
TI - Investigation of extreme weather, ocean current, wave, and coastal flooding during Hurricane Florence (2018) using the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) model
AU - Zambon, J.B.
AU - He, R.
AU - Warner, J.C.
AU - Hegermiller, C.
T2 - 100th Annual American Meteorological Society (AMS) Annual Meeting
C2 - 2020///
CY - Boston, MA
DA - 2020///
PY - 2020/1/12/
ER -
TY - JOUR
TI - Global emissions of NH3, NOx, and N2O from biomass burning and the impact of climate change
AU - Bray, Casey D.
AU - Battye, William H.
AU - Aneja, Viney
AU - Schlesinger, William H.
T2 - JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION
AB - Emissions of ammonia (NH3), oxides of nitrogen (NOx; NO +NO2), and nitrous oxide (N2O) from biomass burning were quantified on a global scale for 2001 to 2015. On average biomass burning emissions at a global scale over the period were as follows: 4.53 ± 0.51 Tg NH3 year−1, 14.65 ± 1.60 Tg NOx year−1, and 0.97 ± 0.11 Tg N2O year−1. Emissions were comparable to other emissions databases. Statistical regression models were developed to project NH3, NOx, and N2O emissions from biomass burning as a function of burn area. Two future climate scenarios (RCP 4.5 and RCP 8.5) were analyzed for 2050–2055 (“mid-century”) and 2090–2095 (“end of century”). Under the assumptions made in this study, the results indicate emissions of all species are projected to increase under both the RCP 4.5 and RCP 8.5 climate scenarios.Implications: This manuscript quantifies emissions of NH3, NOx, and N2O on a global scale from biomass burning from 2001–2015 then creates regression models to predict emissions based on climate change. Because reactive nitrogen emissions have such an important role in the global nitrogen cycle, changes in these emissions could lead to a number of health and environmental impacts.
DA - 2020///
PY - 2020///
DO - 10.1080/10962247.2020.1842822
VL - 71
IS - 1
SP - 102–114
ER -
TY - JOUR
TI - Modeling and measurements of ammonia from poultry operations: Their emissions, transport, and deposition in the Chesapeake Bay
AU - Baker, J.
AU - Battye, W.H.
AU - Robarge, W.
AU - Pal Arya, S.
AU - Aneja, V.P.
T2 - Science of the Total Environment
AB - The goal of this study is to determine how much ammonia/nitrogen is being deposited to the Maryland Eastern Shore land and the Chesapeake Bay from poultry operations on Maryland's Eastern Shore. We simulated the fate of ammonia/nitrogen emitted (using emission factors from the U.S. EPA in conjunction with Carnegie-Mellon University) from 603 poultry facilities using the air quality model, AERMOD. The model domain was approximately 134 km by 230 km (and covers the full land area of Maryland's Eastern Shore), with a horizontal resolution of 2 km by 2 km. Ammonia concentration observations were made at 23 sites across Maryland's Eastern Shore during two periods (September and October 2017) in order to calibrate the model. An ammonia deposition velocity of 2.4 cm/sec was selected based on the sensitivity analysis of results for the simulation of a large poultry facility, and this value fell within the range of measurements reported in the scientific literature downwind of Concentrated Animal Feeding Operations (CAFOs). The ammonia deposition velocity of 2.4 cm/s leads to an estimated total annual ammonia deposition of 11,100 Megagrams/year (10,600 Mg/yr deposition to land, and 508 Mg/yr deposition to water (1 Mg = 1,000,000 g = 1.1023 US Tons)). In addition, model simulations indicate that ~72.4% of ammonia emissions from poultry animal feeding operations would be deposited within the modeling domain. However, this deposited ammonia/nitrogen may be transported through waterways from the land mass and ground water to the Chesapeake Bay. A comprehensive sensitivity analysis of the assumed ammonia deposition velocity (ranging from 0.15 to 3.0 cm/s) on estimated ammonia annual deposition is provided. Using the lower limit of an ammonia deposition velocity of 0.15 cm/s gives much smaller estimated total annual ammonia deposition of 2,040 Mg/yr (1,880 Mg/yr deposition to land and 163 Mg/yr deposition to water).
DA - 2020///
PY - 2020///
DO - 10.1016/j.scitotenv.2019.135290
VL - 706
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076257599&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Anthropocene: Transdisciplinary Shorthand for Human Disruption of the Earth System
AU - Koster, Emlyn
T2 - GEOSCIENCE CANADA
AB - Increasingly, deliberations to potentially add the Anthropocene to the Geological Time Scale in recognition of humanity’s environmental impacts and stratigraphic record are attracting interest from non-geological disciplines and the news media. The 35 member Anthropocene Working Group, a constituent body of the International Commission on Stratigraphy, recently concluded that the worldwide fallout of radionuclides from atomic bomb testing in the mid-20th century best defines the base of the Anthropocene. With a search for the optimal ‘golden spike’ locality in progress as a key step toward any ratification by the International Union of Geological Sciences, there are widely held views outside of geological circles that the Anthropocene is already designated as an epoch. Regardless of its eventual formal or informal standing, this article opines that the term Anthropocene has become valuable shorthand for recognizing humanity as the dominant species which, in a geological nanosecond, has extensively detached itself from the Earth System, endangering the future of both. Accordingly, this article urges the entire geological profession to engage with the work of the Anthropocene Working Group and, as the originator of the term, to coalesce its activities with those of other disciplines concerned with environmental health and linked human health challenges. RÉSUMÉDe plus en plus, les délibérations visant à éventuellement ajouter l'Anthropocène à l'échelle du temps géologique en reconnaissance des impacts environnementaux de l'humanité et des données stratigraphiques suscitent l'intérêt des disciplines non géologiques et des médias. Les 35 membres du Groupe de travail sur l'Anthropocène, un organe constitutif de la Commission internationale de stratigraphie, ont récemment conclu que les retombées mondiales des radionucléides résultant des essais de bombes atomiques au milieu du XXe siècle définissent le mieux la base de l'Anthropocène. Avec la recherche de la localité de référence optimale du « clou d'or » en cours comme étape clé vers toute ratification par l'Union internationale des sciences géologiques, il existe des opinions largement partagées en dehors des cercles géologiques selon lesquelles l'Anthropocène est déjà désigné comme une époque. Indépendamment de sa position finale formelle ou informelle, cet article estime que le terme Anthropocène est devenu un raccourci précieux pour reconnaître l'humanité comme l'espèce dominante qui, dans une nanoseconde géologique, s'est largement dissocié du système terrestre, mettant en danger l'avenir des deux. Par conséquent, cet article exhorte l'ensemble de la profession géologique à s'engager dans les travaux du Groupe de travail sur l'Anthropocène et, en tant que créateur du terme, à fusionner ses activités avec celles d'autres disciplines concernées par la santé environnementale et les défis liés à la santé humaine.
DA - 2020///
PY - 2020///
DO - 10.12789/geocanj.2020.47.160
VL - 47
IS - 1-2
SP - 59-64
SN - 0315-0941
ER -
TY - RPRT
TI - Southeast Atlantic and Gulf of Mexico Region Ocean Acidification Research
DA - 2020/7/1/
PY - 2020/7/1/
ER -
TY - JOUR
TI - Frequency of Animal Leptospirosis in the Southern United States and the Implications for Human Health
AU - Blessington, Tyann
AU - Schenck, Anna P.
AU - Levine, Jay F.
T2 - Southern Medical Journal
AB - Leptospirosis is a zoonotic disease with symptoms in humans and animals, ranging from subclinical to serious and fatal. The disease occurs worldwide, but there is limited recognition of the public and animal health risks it poses in the southern United States. A systematic review of the frequency of animal leptospirosis in 17 states and jurisdictions covering the southern continental United States was performed to advance our understanding of the pathogen's distribution and identify transmission patterns that could be targeted for prevention efforts. Fifty-two articles, spanning >100 years, met the analysis criteria. A wide range of techniques were used to measure seroprevalence and isolate the bacteria. The assessment identified exposure to Leptospira spp and Leptospira spp infection among a diverse range of species, spanning 22 animal families within 14 states, suggesting that the pathogen is distributed throughout the southern region. Disease frequency trends were assessed among animals in various habitats (all habitats, nonwild habitats, and wild habitats). The frequency of Leptospira spp detection in animals in wild habitats increased slightly over time (<0.2%/year). We identified reports of 11 human leptospirosis illness clusters and outbreaks in the southern United States. Exposure to potentially contaminated surface waters were documented for at least seven of the events, and interactions with infected or likely infected animals were documented for at least six of the events. This analysis highlights the need for stronger partnerships across the public and animal health fields to enhance diagnostics, surveillance, and reporting. The early identification of leptospirosis in animals may serve as an indicator of environmental contamination and trigger prevention measures, such as vaccinating companion animals and livestock, use of potable water, and the wearing of waterproof protective clothing near water that may be contaminated.
DA - 2020/5//
PY - 2020/5//
DO - 10.14423/SMJ.0000000000001093
VL - 113
IS - 5
SP - 240-249
LA - en
OP -
SN - 1541-8243 0038-4348
UR - http://dx.doi.org/10.14423/SMJ.0000000000001093
DB - Crossref
ER -
TY - JOUR
TI - Near Ground Wind Profiles of Tornadic and Nontornadic Environments in the United States and Europe from ERAS Reanalyses
AU - Coffer, Brice E.
AU - Taszarek, Mateusz
AU - Parker, Matthew D.
T2 - WEATHER AND FORECASTING
AB - Abstract The near-ground wind profile exhibits significant control over the organization, intensity, and steadiness of low-level updrafts and mesocyclones in severe thunderstorms, and thus their probability of being associated with tornadogenesis. The present work builds upon recent improvements in supercell tornado forecasting by examining the possibility that storm-relative helicity (SRH) integrated over progressively shallower layers has increased skill in differentiating between significantly tornadic and nontornadic severe thunderstorms. For a population of severe thunderstorms in the United States and Europe, sounding-derived parameters are computed from the ERA5 reanalysis, which has significantly enhanced vertical resolution compared to prior analyses. The ERA5 is shown to represent U.S. convective environments similarly to the Storm Prediction Center’s mesoscale surface objective analysis, but its greater number of vertical levels in the lower troposphere permits calculations to be performed over shallower layers. In the ERA5, progressively shallower layers of SRH provide greater discrimination between nontornadic and significantly tornadic thunderstorms in both the United States and Europe. In the United States, the 0–100 m AGL layer has the highest forecast skill of any SRH layer tested, although gains are comparatively modest for layers shallower than 0–500 m AGL. In Europe, the benefit from using shallower layers of SRH is even greater; the lower-tropospheric SRH is by far the most skillful ingredient there, far exceeding related composite parameters like the significant tornado parameter (which has negligible skill in Europe).
DA - 2020/12//
PY - 2020/12//
DO - 10.1175/WAF-D-20-0153.1
VL - 35
IS - 6
SP - 2621-2638
SN - 1520-0434
KW - Europe
KW - Wind shear
KW - Severe storms
KW - Supercells
KW - Tornadoes
KW - Mesoscale forecasting
ER -
TY - JOUR
TI - Testing the Trade Wind Charging Mechanism and Its Influence on ENSO Variability
AU - Chakravorty, Soumi
AU - Perez, Renellys C.
AU - Anderson, Bruce T.
AU - Giese, Benjamin S.
AU - Larson, Sarah M.
AU - Pivotti, Valentina
T2 - JOURNAL OF CLIMATE
AB - Abstract During the positive phase of the North Pacific Oscillation, westerly wind anomalies over the subtropical North Pacific substantially increase subsurface heat content along the equator by “trade wind charging” (TWC). TWC provides a direct pathway between extratropical atmospheric circulation and El Niño–Southern Oscillation (ENSO) initiation. Previous model studies of this mechanism lacked the ocean–atmospheric coupling needed for ENSO growth, so it is crucial to examine whether TWC-induced heat content anomalies develop into ENSO events in a coupled model. Here, coupled model experiments, forced with TWC favorable (+TWC) or unfavorable (−TWC) wind stress, are used to examine the ENSO response to TWC. The forcing is imposed on the ocean component of the model through the first winter and then the model evolves in a fully coupled configuration through the following winter. The +TWC (−TWC) forcing consistently charges (discharges) the equatorial Pacific in spring and generates positive (negative) subsurface temperature anomalies. These subsurface temperature anomalies advect eastward and upward along the equatorial thermocline and emerge as like-signed sea surface temperature (SST) anomalies in the eastern Pacific, creating favorable conditions upon which coupled air–sea feedback can act. During the fully coupled stage, warm SST anomalies in +TWC forced simulations are amplified by coupled feedbacks and lead to El Niño events. However, while −TWC forcing results in cool SST anomalies, pre-existing warm SST anomalies in the far eastern equatorial Pacific persist and induce local westerly wind anomalies that prevent consistent development of La Niña conditions. While the TWC mechanism provides adequate equatorial heat content to fuel ENSO development, other factors also play a role in determining whether an ENSO event develops.
DA - 2020/9/1/
PY - 2020/9/1/
DO - 10.1175/JCLI-D-19-0727.1
VL - 33
IS - 17
SP - 7391-7411
SN - 1520-0442
ER -
TY - JOUR
TI - Soundscapes of natural and artificial temperate reefs: similar temporal patterns but distinct spectral content
AU - Van Hoeck, Rebecca V.
AU - Paxton, Avery B.
AU - Bohnenstiehl, DelWayne R.
AU - Taylor, J. Christopher
AU - Fodrie, F. Joel
AU - Nowacek, Douglas P.
AU - Voss, Christine M.
AU - Peterson, Charles H.
T2 - MARINE ECOLOGY PROGRESS SERIES
AB - Marine soundscapes often differ among habitats; however, relatively little is known about whether soundscapes on naturally occurring habitats differ from soundscapes on human-made structures. To address this knowledge gap, we investigated whether temporal and spectral characteristics of biological sound production differ between natural and artificial offshore reefs. Specifically, we analyzed recordings from 5 week-long hydrophone deployments on 2 natural rocky reefs and 2 artificial reefs on the North Carolina, USA, continental shelf. Analysis of sound pressure levels (SPLs) on hourly and seasonal scales revealed similar temporal patterns between the reef types. These patterns were largely driven by 4 dominant fish vocalizers with seasonal chorusing patterns, including a toadfish Opsanus sp. Despite similar temporal patterns within reef types, soundscape spectral content was more similar within than between reef types, especially during the April deployment, which had the most acoustic activity. Our findings suggest that the soundscapes of shipwreck artificial reefs may differ from the soundscapes of natural rocky reefs, possibly due to differing community composition. As sound plays an important role in the navigation and settlement of many marine species, soundscape differences between natural and artificial habitats could affect ecosystem function through species behavior and interactions.
DA - 2020/9/10/
PY - 2020/9/10/
DO - 10.3354/meps13434
VL - 649
SP - 35-51
SN - 1616-1599
KW - Marine soundscape
KW - Artificial reef
KW - Temperate reef
KW - Spectral dissimilarity index
KW - Bioacoustics
ER -
TY - JOUR
TI - Insights into Supercells and Their Environments from Three Decades of Targeted Radiosonde Observations
AU - Coniglio, Michael C.
AU - Parker, Matthew D.
T2 - MONTHLY WEATHER REVIEW
AB - Abstract Hundreds of supercell proximity soundings obtained for field programs over the central United States are analyzed to reconcile differences in recent studies and to refine our knowledge of supercell environments. The large, storm-centric observation-based dataset and high vertical resolution of the sounding data provide an unprecedented look at supercell environments. Not surprisingly, storm-relative environmental helicity (SRH) is found to be larger in tornadic soundings than in nontornadic soundings. The primary finding that departs from previous studies is that storm-relative winds contribute substantially to the larger SRH. Stronger ground-relative winds and more rightward-deviant storm motions contribute to the larger storm-relative winds for the tornadic soundings. Spatial analyses of the soundings reveal lower near-ground pressure perturbations and stronger low- to midlevel cyclonic flow for the tornadic soundings, which suggests stronger mesocyclones, perhaps explaining the more rightward-deviant motions. Differences in the mean critical angle between the tornadic and nontornadic soundings are small and do not contribute to the larger mean SRH, but the tornadic soundings do have fewer instances of smaller (<60°) critical angles. Furthermore, the critical angle is shown to be a function of azimuth from the updraft. Other results include a low-to-the-ground (~250 m on average) hodograph kink for both the tornadic and nontornadic soundings and few notable differences in thermodynamic quantities, except for the expected lower LCLs related to higher RH for the tornadic soundings, somewhat smaller 0–3 km lapse rates in tornadic environments related to weaker/shallower capping inversions, and larger 0–3 km CAPE in near-field environments.
DA - 2020/12//
PY - 2020/12//
DO - 10.1175/MWR-D-20-0105.1
VL - 148
IS - 12
SP - 4893-4915
SN - 1520-0493
KW - Atmosphere
KW - Mesocyclones
KW - Severe storms
KW - Storm environments
KW - Supercells
KW - Tornadoes
ER -
TY - JOUR
TI - Tropical Cyclone Wind Speed Retrieval from Dual-Polarization Sentinel-1 EW Mode Products
AU - Gao, Yuan
AU - Guan, Changlong
AU - Sun, Jian
AU - Xie, Lian
T2 - JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY
AB - Abstract Recent studies indicate that the cross-polarization synthetic aperture radar (SAR) images have the ability of retrieving high wind speed on ocean surface without wind direction input. This study presents a new approach for tropical cyclone (TC) wind speed retrieval utilizing thermal-noise-removed Sentinel-1 dual-polarization (VV + VH) Extra-Wide Swath (EW) Mode products. Based on 20 images of 9 TCs observed in the 2016 and 2018 and SAR-collocated European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation reanalysis (ERA5) data and the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division’s (HRD) Real-time Hurricane Wind Analysis System (H*Wind) data, a subswath-based geophysical model function (GMF) Sentinel-1 EW Mode Wind Speed Retrieval Model after Noise Removal (S1EW.NR) is developed and validated statistically. TC wind speed is retrieved by using the proposed GMF and the C-band model 5.N (CMOD5.N). The results show that the wind speeds retrieved by the S1EW.NR model are in good agreement with wind references up to 31 m s −1 . The correlation coefficient, bias, and standard deviation between the retrieval results and reference wind speeds are 0.74, −0.11, and 3.54 m s −1 , respectively. Comparison of the wind speeds retrieved from both channels suggests that the cross-polarized signal is more suitable for high–wind speed retrieval, indicating the promising capability of cross-polarization SAR for TC monitoring.
DA - 2020/9//
PY - 2020/9//
DO - 10.1175/JTECH-D-19-0148.1
VL - 37
IS - 9
SP - 1713-1724
SN - 1520-0426
ER -
TY - JOUR
TI - A statistical and numerical modeling approach for spatiotemporal reconstruction of glaciations in the Central Asian mountains
AU - Saha, Sourav
AU - Owen, Lewis A.
AU - Orr, Elizabeth N.
AU - Caffee, Marc W.
T2 - METHODSX
AB - Reconstructing Quaternary regional glaciations throughout the Himalaya, Tibet, and the adjoining mountains in Central Asia is challenging due to geological biases towards limited preservation of glacial deposits and chronological uncertainties. Here, we offer several statistical and mathematical model codes in R, in excel, and in MATLAB useful to develop regional glacial chronostratigraphies, especially in areas with distinct orographically-modulated climate. A complete R code is provided to generate a regional climate map using Cluster Analysis (CA) and Principal Component Analysis (PCA). Additional R codes include reduced chi-squared, Chauvenet's criterion, radial plotter/abanico plot, finite mixture model, and Student's t-test. These methods are useful in reconstructing the timing of local and regional glacial chronologies. An excel code to calculate equilibrium-line altitudes (ELAs) and steps to reconstruct glacier hypsometry are also made available to further aid to our understanding of the extent of paleoglaciations. A MATLAB code of the linear glacier flow model is included to reconstruct paleotemperatures using the length and slope of a glacier during past advances.•R statistical codes can be used/modified without restrictions for other researchers.•Easy steps to calculate ELAs and glacier hypsometry from the same data.•Paleo-temperature reconstruction utilizes already developed glacial chronologies and maps.
DA - 2020///
PY - 2020///
DO - 10.1016/j.mex.2020.100820
VL - 7
SP -
SN - 2215-0161
KW - Glaciation
KW - Cosmogenic isotopes
KW - Paleoclimate modeling
KW - Cluster analysis
KW - Principal component analysis
KW - Equilibrium-line altitudes
ER -
TY - JOUR
TI - Studying Scale Dependency of Aerosol-Cloud Interactions Using Multiscale Cloud Formulations
AU - Glotfelty, Timothy
AU - Alapaty, Kiran
AU - He, Jian
AU - Hawbecker, Patrick
AU - Song, Xiaoliang
AU - Zhang, Guang
T2 - JOURNAL OF THE ATMOSPHERIC SCIENCES
AB - The WRF-ACI model configuration is used to investigate the scale dependency of aerosol-cloud interactions (ACI) across the "grey zone" scales for grid and subgrid-scale clouds. The impacts of ACI on weather are examined across regions in the eastern and western U. S. at 36, 12, 4, and 1 km grid spacing for short-term periods during the summer of 2006. ACI impacts are determined by comparing simulations with current climatological aerosol levels to simulations with aerosol levels reduced by 90%. The aerosol-cloud lifetime effect is found to be the dominant process leading to suppressed precipitation in regions of the eastern U.S., while regions in the western U. S. experience offsetting impacts on precipitation from the cloud lifetime effect and other effects that enhance precipitation. Generally, the cloud lifetime effect weakens with decreasing grid spacing due to a decrease in relative importance of autoconversion compared to accretion. Subgrid-scale ACI are dominant at 36 km, while grid-scale ACI are dominant at 4 and 1 km. At 12 km grid spacing, grid-scale and subgrid-scale ACI processes are comparable in magnitude and spatial coverage, but random perturbations in grid-scale-ACI impacts make the overall grid-scale-ACI impact appear muted. This competing behavior of grid and subgrid-scale clouds complicate the understanding of ACI at 12 km within the current WRF modeling framework. The work implies including subgrid-scale-cloud microphysics and ice/mixed phase cloud ACI processes may be necessary in weather and climate models to study ACI effectively.
DA - 2020/11//
PY - 2020/11//
DO - 10.1175/JAS-D-19-0203.1
VL - 77
IS - 11
SP - 3847-3868
SN - 1520-0469
KW - Cloud parameterizations
KW - Clouds
KW - Convective parameterization
KW - Cumulus clouds
KW - Model evaluation/performance
ER -
TY - JOUR
TI - A review of "pyrite disease" for paleontologists, with potential focused interventions
AU - Tacker, R. Chris
T2 - PALAEONTOLOGIA ELECTRONICA
DA - 2020///
PY - 2020///
DO - 10.26879/104
VL - 23
IS - 3
SP -
SN - 1094-8074
KW - pyrite
KW - oxidation
KW - humidity
KW - collections
KW - treatment
KW - fossils
ER -
TY - JOUR
TI - ENSO and Pacific Decadal Variability in the Community Earth System Model Version 2
AU - Capotondi, A.
AU - Deser, C.
AU - Phillips, A. S.
AU - Okumura, Y.
AU - Larson, S. M.
T2 - JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
AB - Abstract This study presents a description of the El Niño–Southern Oscillation (ENSO) and Pacific Decadal Variability (PDV) in a multicentury preindustrial simulation of the Community Earth System Model Version 2 (CESM2). The model simulates several aspects of ENSO relatively well, including dominant timescale, tropical and extratropical precursors, composite evolution of El Niño and La Niña events, and ENSO teleconnections. The good model representation of ENSO spectral characteristics is consistent with the spatial pattern of the anomalous equatorial zonal wind stress in the model, which results in the correct adjustment timescale of the equatorial thermocline according to the delayed/recharge oscillator paradigms, as also reflected in the realistic time evolution of the equatorial Warm Water Volume. PDV in the model exhibits a pattern that is very similar to the observed, with realistic tropical and South Pacific signatures which were much weaker in some of the CESM2 predecessor models. The tropical component of PDV also shows an association with ENSO decadal modulation which is similar to that found in observations. However, the ENSO amplitude is about 30% larger than observed in the preindustrial CESM2 simulation, and even larger in the historical ensemble, perhaps as a result of anthropogenic influences. In contrast to observations, the largest variability is found in the central Pacific rather than in the eastern Pacific, a discrepancy that somewhat hinders the model's ability to represent a full diversity in El Niño spatial patterns and appears to be associated with an unrealistic confinement of the precipitation anomalies to the western Pacific.
DA - 2020/12//
PY - 2020/12//
DO - 10.1029/2019MS002022
VL - 12
IS - 12
SP -
SN - 1942-2466
KW - Community Earth System Model
KW - El Nino–
KW - Southern Oscillation
KW - Pacific Decadal Variability and decadal ENSO modulation
KW - ENSO diversity
KW - ENSO precursors
KW - ENSO teleconnections
ER -
TY - JOUR
TI - The Aichi Biodiversity Targets: achievements for marine conservation and priorities beyond 2020
AU - Carr, Hannah
AU - Abas, Marina
AU - Boutahar, Loubna
AU - Caretti, Olivia N.
AU - Chan, Wing Yan
AU - Chapman, Abbie S. A.
AU - Mendonca, Sarah N.
AU - Engleman, Abigail
AU - Ferrario, Filippo
AU - Simmons, Kayelyn R.
AU - Verdura, Jana
AU - Zivian, Anna
T2 - PEERJ
AB - In 2010 the Conference of the Parties (COP) for the Convention on Biological Diversity revised and updated a Strategic Plan for Biodiversity 2011–2020, which included the Aichi Biodiversity Targets. Here a group of early career researchers mentored by senior scientists, convened as part of the 4th World Conference on Marine Biodiversity, reflects on the accomplishments and shortfalls under four of the Aichi Targets considered highly relevant to marine conservation: target 6 (sustainable fisheries), 11 (protection measures), 15 (ecosystem restoration and resilience) and 19 (knowledge, science and technology). We conclude that although progress has been made towards the targets, these have not been fully achieved for the marine environment by the 2020 deadline. The progress made, however, lays the foundations for further work beyond 2020 to work towards the 2050 Vision for Biodiversity. We identify key priorities that must be addressed to better enable marine biodiversity conservation efforts moving forward.
DA - 2020/12/21/
PY - 2020/12/21/
DO - 10.7717/peerj.9743
VL - 8
SP -
SN - 2167-8359
KW - Aichi
KW - Biodiversity
KW - Target
KW - 2020
KW - Marine
KW - Conservation
KW - Priorities
ER -
TY - JOUR
TI - Multianalyzer Spectroscopic Data Fusion for Soil Characterization
AU - Hark, Richard R.
AU - Throckmorton, Chandra S.
AU - Harmon, Russell S.
AU - Plumer, John R.
AU - Harmon, Karen A.
AU - Harrison, J. Bruce
AU - Hendrickx, Jan M. H.
AU - Clausen, Jay L.
T2 - APPLIED SCIENCES-BASEL
AB - The ability to rapidly conduct in-situ chemical analysis of multiple samples of soil and other geological materials in the field offers many advantages over a traditional approach that involves collecting samples for subsequent examination in the laboratory. This study explores the application of complementary spectroscopic analyzers and a data fusion methodology for the classification/discrimination of >100 soil samples from sites across the United States. Commercially available, handheld analyzers for X-ray fluorescence spectroscopy (XRFS), Raman spectroscopy (RS), and laser-induced breakdown spectroscopy (LIBS) were used to collect data both in the laboratory and in the field. Following a common data pre-processing protocol, principal component analysis (PCA) and partial least squares discriminant analysis (PLSDA) were used to build classification models. The features generated by PLSDA were then used in a hierarchical classification approach to assess the relative advantage of information fusion, which increased classification accuracy over any of the individual sensors from 80-91% to 94% and 64-93% to 98% for the two largest sample suites. The results show that additional testing with data sets for which classification with individual analyzers is modest might provide greater insight into the limits of data fusion for improving classification accuracy.
DA - 2020/12//
PY - 2020/12//
DO - 10.3390/app10238723
VL - 10
IS - 23
SP -
SN - 2076-3417
KW - laser-induced breakdown spectroscopy
KW - LIBS
KW - Raman spectroscopy
KW - RS
KW - X-ray fluorescence spectroscopy
KW - XRFS
KW - chemometrics
KW - machine learning
KW - multianalyzer data fusion
ER -
TY - JOUR
TI - Health and economic impacts of air pollution induced by weather extremes over the continental US
AU - Zhang, Yang
AU - Yang, Peilin
AU - Gao, Yang
AU - Leung, Ruby L.
AU - Bell, Michelle L.
T2 - ENVIRONMENT INTERNATIONAL
AB - Extreme weather events may enhance ozone (O3) and fine particulate matter (PM2.5) pollution, causing additional adverse health effects. This work aims to evaluate the health and associated economic impacts of changes in air quality induced by heat wave, stagnation, and compound extremes under the Representative Concentration Pathways (RCP) 4.5 and 8.5 climate scenarios. The Environmental Benefits Mapping and Analysis Program-Community Edition is applied to estimate health and related economic impacts of changes in surface O3 and PM2.5 levels due to heat wave, stagnation, and compound extremes over the continental U.S. during past (i.e., 2001–2010) and future (i.e., 2046–2055) decades under the two RCP scenarios. Under the past and future decades, the weather extremes-induced concentration increases may lead to several tens to hundreds O3-related deaths and several hundreds to over ten thousands PM2.5-related deaths annually. High mortalities and morbidities are estimated for populated urban areas with strong spatial heterogeneities. The estimated annual costs for these O3 and PM2.5 related health outcomes are $5.5–12.5 and $48.6–140.7 billion U.S. dollar for mortalities, and $8.9–97.8 and $19.5–112.5 million for morbidities, respectively. Of the extreme events, the estimated O3– and PM2.5–related mortality and morbidity attributed to stagnation are the highest, followed by heat wave or compound extremes. Large increases in heat wave and compound extreme events in the future decade dominate changes in mortality during these two extreme events, whereas population growth dominates changes in mortality during stagnation that is projected to occur less frequently. Projected reductions of anthropogenic emissions under both RCP scenarios compensate for the increased mortality due to increased occurrence for heat wave and compound extremes in the future. These results suggest a need to further reduce air pollutant emissions during weather extremes to minimize the adverse impacts of weather extremes on air quality and human health.
DA - 2020/10//
PY - 2020/10//
DO - 10.1016/j.envint.2020.105921
VL - 143
SP -
SN - 1873-6750
KW - Weather extremes
KW - O-3
KW - PM2.5
KW - Mortality
KW - Morbidity
KW - Continental US
ER -
TY - JOUR
TI - Implications of the Coronavirus on Sales Tax Revenue and Local Government Fiscal Health
AU - McDonald, Bruce D., III
AU - Larson, Sarah E.
T2 - JOURNAL OF PUBLIC AND NONPROFIT AFFAIRS
AB - The outbreak of COVID—19 has raised considerable alarm about public health and safety. The response to the outbreak, however, has also brought concern regarding its impact on local governments in the United States. Local governments have been a primary respondent in the fight against the COVID—19 disease, but the response has also reduced income from a key source of revenue, sales tax. Using North Carolina counties as a case study, we explore the shock to sales and use tax revenue faced by local governments from COVID—19; we, then, estimate its impact on county fiscal health. Our results show that while many local governments were financially struggling before the outbreak, the drop in sales tax revenue severely threatens their ability to provide continued response to the virus as well as their ability to remain solvent.
DA - 2020///
PY - 2020///
DO - 10.20899/jpna.6.3.377-400
VL - 6
IS - 3
SP - 377-400
SN - 2381-3717
KW - COVID-19
KW - Sales Tax
KW - Fiscal Health
KW - County Government
ER -
TY - JOUR
TI - Picophytoplankton dynamics in a large temperate estuary and impacts of extreme storm events
AU - Paerl, Ryan W.
AU - Venezia, Rebecca E.
AU - Sanchez, Joel J.
AU - Paerl, Hans W.
T2 - SCIENTIFIC REPORTS
AB - Abstract Picophytoplankton (PicoP) are increasingly recognized as significant contributors to primary productivity and phytoplankton biomass in coastal and estuarine systems. Remarkably though, PicoP composition is unknown or not well-resolved in several large estuaries including the semi-lagoonal Neuse River Estuary (NRE), a tributary of the second largest estuary-system in the lower USA, the Pamlico-Albemarle Sound. The NRE is impacted by extreme weather events, including recent increases in precipitation and flooding associated with tropical cyclones. Here we examined the impacts of moderate to extreme (Hurricane Florence, September 2018) precipitation events on NRE PicoP abundances and composition using flow cytometry, over a 1.5 year period. Phycocyanin-rich Synechococcus -like cells were the most dominant PicoP, reaching ~ 10 6 cells mL −1 , which highlights their importance as key primary producers in this relatively long residence-time estuary. Ephemeral “blooms” of picoeukaryotic phytoplankton (PEUK) during spring and after spikes in river flow were also detected, making PEUK periodically major contributors to PicoP biomass (up to ~ 80%). About half of the variation in PicoP abundance was explained by measured environmental variables. Temperature explained the most variation (24.5%). Change in total dissolved nitrogen concentration, an indication of increased river discharge, explained the second-most variation in PicoP abundance (15.9%). The short-term impacts of extreme river discharge from Hurricane Florence were particularly evident as PicoP biomass was reduced by ~ 100-fold for more than 2 weeks. We conclude that precipitation is a highly influential factor on estuarine PicoP biomass and composition, and show how ‘wetter’ future climate conditions will have ecosystem impacts down to the smallest of phytoplankton.
DA - 2020/12/16/
PY - 2020/12/16/
DO - 10.1038/s41598-020-79157-6
VL - 10
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Elevated organic carbon pulses persist in estuarine environment after major storm events
AU - Asmala, Eero
AU - Osburn, Christopher
AU - Paerl, Ryan
AU - Paerl, Hans W.
T2 - LIMNOLOGY AND OCEANOGRAPHY LETTERS
AB - Abstract Estuaries regulate transport of dissolved organic carbon (DOC) from land to ocean. Export of terrestrial DOC from coastal watersheds is exacerbated by increasing major rainfall and storm events and human activities, leading to pulses of DOC that are shunted through rivers downstream to estuaries. Despite an upward trend of extreme events, the fate of the pulsed terrestrial DOC in estuaries remains unclear. We analyzed the effects of seven major tropical cyclones (TC) from 1999 to 2017 on the quantity and fate of DOC in the Neuse River Estuary (NC, USA). Significant TC‐induced increases in DOC were observed throughout the estuary; the increase lasting from around 50 d at head‐of‐tide to over 6 months in lower estuary. Our results suggest that pulsed terrestrial DOC associated with TCs temporarily overwhelms the estuarine filter's abiotic and biotic degradation capacity under such high flow events, enhancing the shunt of terrestrial carbon to the coastal ocean.
DA - 2020///
PY - 2020///
DO - 10.1002/lol2.10169
ER -
TY - JOUR
TI - More is Not Better: The Emotional Dynamics of an Excellent Experience
AU - Mitas, Ondrej
AU - Mitasova, Helena
AU - Millar, Garrett
AU - Boode, Wilco
AU - Neveu, Vincent
AU - Hover, Moniek
AU - Eijnden, Frank
AU - Bastiaansen, Marcel
T2 - JOURNAL OF HOSPITALITY & TOURISM RESEARCH
AB - Emotions embody the value in tourism experiences and drive essential outcomes such as intent to recommend. Current models do not explain how the ebb and flow of emotional arousal during an experience relate to outcomes, however. We analyzed 15 participants’ experiences at the Vincentre museum and guided village tour in Nuenen, the Netherlands. This Vincent van Gogh-themed experience led to a wide range of intent to recommend and emotional arousal, measured as continuous phasic skin conductance, across participants and exhibits. Mixed-effects analyses modeled emotional arousal as a function of proximity to exhibits and intent to recommend. Experiences with the best outcomes featured moments of both high and low emotional arousal, not one continuous “high,” with more emotion during the middle of the experience. Tourist experience models should account for a complex relationship between emotions experienced and outcomes such as intent to recommend. Simply put, more emotion is not always better.
DA - 2020///
PY - 2020///
DO - 10.1177/1096348020957075
KW - emotions
KW - psychology
KW - heritage tourism
KW - experience
KW - skin conductance
ER -
TY - JOUR
TI - Tesserae on Venus may preserve evidence of fluvial erosion
AU - Khawja, S.
AU - Ernst, R. E.
AU - Samson, C.
AU - Byrne, P. K.
AU - Ghail, R. C.
AU - MacLellan, L. M.
T2 - NATURE COMMUNICATIONS
AB - Fluvial erosion is usually assumed to be absent on Venus, precluded by a high surface temperature of ~450 °C and supported by extensive uneroded volcanic flows. However, recent global circulation models suggest the possibility of Earth-like climatic conditions on Venus for much of its earlier history, prior to catastrophic runaway greenhouse warming. We observe that the stratigraphically oldest, geologically most complex units, tesserae, exhibit valley patterns morphologically similar to the patterns resulting from fluvial erosion on Earth. Given poor topographic resolution, we use an indirect technique to recognize valleys, based on the pattern of lava flooding of tesserae margins by adjacent plains volcanism. These observed valley patterns are attributed to primary geology, tectonic deformation, followed by fluvial erosion (and lesser wind erosion). This proposed fluvial erosion in tesserae provides support for climate models for a cool, wet climate on early Venus and could be an attractive research theme for future Venus missions.
DA - 2020///
PY - 2020///
DO - 10.1038/s41467-020-19336-1
VL - 11
IS - 1
ER -
TY - JOUR
TI - Sources of Tropical Subseasonal Skill in the CFSv2
AU - Schreck, Carl J., III
AU - Janiga, Matthew A.
AU - Baxter, Stephen
T2 - MONTHLY WEATHER REVIEW
AB - Abstract This study applies Fourier filtering to a combination of rainfall estimates from TRMM and forecasts from the CFSv2. The combined data are filtered for low-frequency (LF, ≥120 days) variability, the MJO, and convectively coupled equatorial waves. The filtering provides insight into the sources of skill for the CFSv2. The LF filter, which encapsulates persistent anomalies generally corresponding with SSTs, has the largest contribution to forecast skill beyond week 2. Variability within the equatorial Pacific is dominated by its response to ENSO, such that both the unfiltered and the LF-filtered forecasts are skillful over the Pacific through the entire 45-day CFSv2 forecast. In fact, the LF forecasts in that region are more skillful than the unfiltered forecasts or any combination of the filters. Verifying filtered against unfiltered observations shows that subseasonal variability has very little opportunity to contribute to skill over the equatorial Pacific. Any subseasonal variability produced by the model is actually detracting from the skill there. The MJO primarily contributes to CFSv2 skill over the Indian Ocean, particularly during March–May and MJO phases 2–5. However, the model misses opportunities for the MJO to contribute to skill in other regions. Convectively coupled equatorial Rossby waves contribute to skill over the Indian Ocean during December–February and the Atlantic Ocean during September–November. Convectively coupled Kelvin waves show limited potential skill for predicting weekly averaged rainfall anomalies since they explain a relatively small percent of the observed variability.
DA - 2020/4//
PY - 2020/4//
DO - 10.1175/MWR-D-19-0289.1
VL - 148
IS - 4
SP - 1553-1565
SN - 1520-0493
ER -
TY - JOUR
TI - Modes of Storm-Scale Variability and Tornado Potential in VORTEX2 Near- and Far-Field Tornadic Environments
AU - Flournoy, Matthew D.
AU - Coniglio, Michael C.
AU - Rasmussen, Erik N.
AU - Furtado, Jason C.
AU - Coffer, Brice E.
T2 - MONTHLY WEATHER REVIEW
AB - Abstract Some supercellular tornado outbreaks are composed almost entirely of tornadic supercells, while most consist of both tornadic and nontornadic supercells sometimes in close proximity to each other. These differences are related to a balance between larger-scale environmental influences on storm development as well as more chaotic, internal evolution. For example, some environments may be potent enough to support tornadic supercells even if less predictable intrastorm characteristics are suboptimal for tornadogenesis, while less potent environments are supportive of tornadic supercells given optimal intrastorm characteristics. This study addresses the sensitivity of tornadogenesis to both environmental characteristics and storm-scale features using a cloud modeling approach. Two high-resolution ensembles of simulated supercells are produced in the near- and far-field environments observed in the inflow of tornadic supercells during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2). All simulated supercells evolving in the near-field environment produce a tornado, and 33% of supercells evolving in the far-field environment produce a tornado. Composite differences between the two ensembles are shown to address storm-scale characteristics and processes impacting the volatility of tornadogenesis. Storm-scale variability in the ensembles is illustrated using empirical orthogonal function analysis, revealing storm-generated boundaries that may be linked to the volatility of tornadogenesis. Updrafts in the near-field ensemble are markedly stronger than those in the far-field ensemble during the time period in which the ensembles most differ in terms of tornado production. These results suggest that storm-environment modifications can influence the volatility of supercellular tornadogenesis.
DA - 2020/10//
PY - 2020/10//
DO - 10.1175/MWR-D-20-0147.1
VL - 148
IS - 10
SP - 4185-4207
SN - 1520-0493
KW - Supercells
KW - Tornadoes
KW - Storm environments
KW - Empirical orthogonal functions
ER -
TY - JOUR
TI - Development of the Truckee River terraces on the northeastern flank of the Sierra Nevada
AU - Wesnousky, Steven G.
AU - Owen, Lewis A.
T2 - GEOMORPHOLOGY
AB - The distribution and elevation of the abandoned strath terraces along the Truckee River in the Carson Range on the eastern flank of the Sierra Nevada are mapped and quantified with measurements from Lidar accompanied by field survey. Each mapped strath terrace is formed by incision into the Hunter Creek Sandstone and deposition of fluvial gravel by the Truckee River. The gravel contains granitic boulders sourced from the glaciated headwaters of the Truckee >20 km upstream from the terraces and display boulders ranging from 4 to 12 m in dimension, in comparison to the <1 m dimension of boulders observed in the bedload of the modern Truckee River. Be-10 terrestrial cosmogenic nuclide (TCN) surface exposure dating places limits on the age distribution of the strath terraces. The terrace sediments are suggested to be glacial outwash deposits, temporally linked with glacial cycles, and to record an average of ~0.3 mm/a tectonic uplift with respect to the Reno Basin over the last ~350 ka. Building upon earlier studies, the observations collected here increase the number of terrace levels previously mapped along the Truckee, provide initial quantitative bounds on the age of their formation, and further point to tectonic uplift as an important component in preserving this most extensive suite of strath terraces along the eastern flank of the Sierra Nevada.
DA - 2020/12/1/
PY - 2020/12/1/
DO - 10.1016/j.geomorph.2020.107399
VL - 370
SP -
SN - 1872-695X
KW - Strath terraces
KW - Sierra Nevada
KW - Glaciation
KW - Cosmogenic exposure age
ER -
TY - JOUR
TI - Surface Pressure a More Skillful Predictor of Normalized Hurricane Damage than Maximum Sustained Wind
AU - Klotzbach, Philip J.
AU - Bell, Michael M.
AU - Bowen, Steven G.
AU - Gibney, Ethan J.
AU - Knapp, Kenneth R.
AU - Schreck, Carl J., III
T2 - BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY
AB - Abstract Atlantic hurricane seasons have a long history of causing significant financial impacts, with Harvey, Irma, Maria, Florence, and Michael combining to incur more than 345 billion USD in direct economic damage during 2017–2018. While Michael’s damage was primarily wind and storm surge-driven, Florence’s and Harvey’s damage was predominantly rainfall and inland flood-driven. Several revised scales have been proposed to replace the Saffir–Simpson Hurricane Wind Scale (SSHWS), which currently only categorizes the hurricane wind threat, while not explicitly handling the totality of storm impacts including storm surge and rainfall. However, most of these newly-proposed scales are not easily calculated in real-time, nor can they be reliably calculated historically. In particular, they depend on storm wind radii, which remain very uncertain. Herein, we analyze the relationship between normalized historical damage caused by continental United States (CONUS) landfalling hurricanes from 1900–2018 with both maximum sustained wind speed ( V max ) and minimum sea level pressure (MSLP). We show that MSLP is a more skillful predictor of normalized damage than V max , with a significantly higher rank correlation between normalized damage and MSLP ( r rank = 0.77) than between normalized damage and V max ( r rank = 0.66) for all CONUS landfalling hurricanes. MSLP has served as a much better predictor of hurricane damage in recent years than V max , with large hurricanes such as Ike (2008) and Sandy (2012) causing much more damage than anticipated from their SSHWS ranking. MSLP is also a more accurately-measured quantity than is V max , making it an ideal quantity for evaluating a hurricane’s potential damage.
DA - 2020/6//
PY - 2020/6//
DO - 10.1175/BAMS-D-19-0062.1
VL - 101
IS - 6
SP - E830-E846
SN - 1520-0477
ER -
TY - JOUR
TI - Hydraulic and geochemical impact of occasional saltwater intrusions through a submarine spring in a karst and thermal aquifer (Balaruc peninsula near Montpellier, France)
AU - Petre, Marie-Amelie
AU - Ladouche, Bernard
AU - Seidel, Jean-Luc
AU - Hemelsdael, Romain
AU - Montety, Veronique
AU - Batiot-Guilhe, Christelle
AU - Lamotte, Claudine
T2 - HYDROLOGY AND EARTH SYSTEM SCIENCES
AB - Abstract. Submarine springs are a common discharge feature of the karst aquifers along the Mediterranean coast. In some instances, occasional and localized saltwater intrusions can occur through the submarine spring and negatively impact the quality of the groundwater resource. The hydraulic and geochemical behaviour of a submarine spring discharging into the Thau Lagoon just offshore of the Balaruc peninsula near Montpellier, France, has been characterized to determine the impacts of such phenomena to better understand the dynamics of a regional karst aquifer and improve its groundwater management. This work is based on both historical and new hydrogeological and geochemical data, illustrating six occasional saltwater intrusion events (from 1967 to 2014) in the Thau Lagoon area (southern France). Hydraulic perturbation of the aquifer is propagated instantly within the Balaruc-les-Bains peninsula and reaches a distance of about 5 km upgradient within 9 d. Comparison of hydraulic heads during seawater intrusion events in 2010 and 2014 indicates an aggravation of the phenomenon with an increase in hydraulic head variations. In contrast, isotopic tracers (87Sr∕86Sr, D/H, 18O∕16O) and rare earth elements (REEs) demonstrate that the geochemical impact of these inversac events is only observed at the local scale but is still perceptible several years after the event. For example, some of the thermal wells had not recovered their initial geochemical state 20 and 40 months after the last two inversac events (2010 and 2014, respectively), suggesting a geochemical legacy of this phenomenon within the complex karst system. By contrast, an adjacent deep karst compartment located south of the study area is not affected by the saltwater intrusion and is characterized by distinctly different hydrodynamic behaviour. Overall, this work on occasional and localized saltwater intrusions constitutes a key step in understanding the dynamics of this complex karstic and thermal aquifer and will support the management of the groundwater resource.
DA - 2020/11/27/
PY - 2020/11/27/
DO - 10.5194/hess-24-5655-2020
VL - 24
IS - 11
SP - 5655-5672
SN - 1607-7938
ER -
TY - JOUR
TI - Dynamics of an intense Alexandrium catenella red tide in the Gulf of Maine: satellite observations and numerical modeling
AU - Li, Yizhen
AU - Stumpf, Richard P.
AU - McGillicuddy, D. J., Jr.
AU - He, Ruoying
T2 - HARMFUL ALGAE
AB - In July 2009, an unusually intense bloom of the toxic dinoflagellate Alexandrium catenella occurred in the Gulf of Maine. The bloom reached high concentrations (from hundreds of thousands to one million cells L−1) that discolored the water and exceeded normal bloom concentrations by a factor of 1000. Using Medium Resolution Imaging Spectrometer (MERIS) imagery processed to target chlorophyll concentrations (>2 µg L−1), patches of intense A. catenella concentration were identified that were consistent with the highly localized cell concentrations observed from ship surveys. The bloom patches were generally aligned with the edge of coastal waters with high-absorption. Dense bloom patches moved onshore in response to a downwelling event, persisted for approximately one week, then dispersed rapidly over a few days and did not reappear. Coupled physical-biological model simulations showed that wind forcing was an important factor in transporting cells onshore. Upward swimming behavior facilitated the horizontal cell aggregation, increasing the simulated maximum depth-integrated cell concentration by up to a factor of 40. Vertical convergence of cells, due to active swimming of A. catenella from the subsurface to the top layer, could explain the additional 25-fold intensification (25 × 40=1000-fold) needed to reach the bloom concentrations that discolored the water. A model simulation that considered upward swimming overestimated cell concentrations downstream of the intense aggregation. This discrepancy between model and observed concentrations suggested a loss of cells from the water column at a time that corresponded to the start of encystment. These results indicated that the joint effect of upward swimming, horizontal convergence, and wind-driven flow contributed to the red water event, which might have promoted the sexual reproduction event that preceded the encystment process.
DA - 2020/11//
PY - 2020/11//
DO - 10.1016/j.hal.2020.101927
VL - 99
SP -
SN - 1878-1470
KW - Red water
KW - Bloom patches
KW - Cell accumulation
KW - Coastal upwelling
KW - Upward swimming
ER -
TY - JOUR
TI - Performance across WorldView-2 and RapidEye for reproducible seagrass mapping
AU - Coffer, Megan M.
AU - Schaeffer, Blake A.
AU - Zimmerman, Richard C.
AU - Hill, Victoria
AU - Li, Jiang
AU - Islam, Kazi A.
AU - Whitman, Peter J.
T2 - REMOTE SENSING OF ENVIRONMENT
AB - Satellite remote sensing offers an effective remedy to challenges in ground-based and aerial mapping that have previously impeded quantitative assessments of global seagrass extent. Commercial satellite platforms offer fine spatial resolution, an important consideration in patchy seagrass ecosystems. Currently, no consistent protocol exists for image processing of commercial data, limiting reproducibility and comparison across space and time. Additionally, the radiometric performance of commercial satellite sensors has not been assessed against the dark and variable targets characteristic of coastal waters. This study compared data products derived from two commercial satellites: DigitalGlobe's WorldView-2 and Planet's RapidEye. A single scene from each platform was obtained at St. Joseph Bay in Florida, USA, corresponding to a November 2010 field campaign. A reproducible processing regime was developed to transform imagery from basic products, as delivered from each company, into analysis-ready data usable for various scientific applications. Satellite-derived surface reflectances were compared against field measurements. WorldView-2 imagery exhibited high disagreement in the coastal blue and blue spectral bands, chronically overpredicting. RapidEye exhibited better agreement than WorldView-2, but overpredicted slightly across all spectral bands. A deep convolutional neural network was used to classify imagery into deep water, land, submerged sand, seagrass, and intertidal classes. Classification results were compared to seagrass maps derived from photointerpreted aerial imagery. This study offers the first radiometric assessment of WorldView-2 and RapidEye over a coastal system, revealing inherent calibration issues in shorter wavelengths of WorldView-2. Both platforms demonstrated as much as 97% agreement with aerial estimates, despite differing resolutions. Thus, calibration issues in WorldView-2 did not appear to interfere with classification accuracy, but could be problematic if estimating biomass. The image processing routine developed here offers a reproducible workflow for WorldView-2 and RapidEye imagery, which was tested in two additional coastal systems. This approach may become platform independent as more sensors become available.
DA - 2020/12/1/
PY - 2020/12/1/
DO - 10.1016/j.rse.2020.112036
VL - 250
SP -
SN - 1879-0704
KW - Remote sensing
KW - Atmospheric correction
KW - WorldView-2
KW - RapidEye
KW - Seagrass
KW - Image classification
ER -
TY - JOUR
TI - The future-climate, current-policy framework: towards an approach linking climate science to sector policy development
AU - Evans, Barbara E.
AU - Rowell, David P.
AU - Semazzi, Frederick H. M.
T2 - ENVIRONMENTAL RESEARCH LETTERS
AB - Abstract That global climate is being altered by human activities is well-established; for specific locations, however, the details of how and when many aspects of the changes will become manifest remains somewhat uncertain. For many policy makers there is a gap between recognising a long-term change and implementing short-term practical responses; therefore many countries are failing to implement changes needed for long-term adaptation. Traditional planning approaches are often closely aligned with near- term political cycles and perform poorly in terms of prioritising interventions that address multi-decadal climate impacts. We propose a novel approach that builds on adaptive planning and lessons from the business sector. The Future-Climate, Current-Policy (FCCP) Framework is based on plausible medium-term future climate scenarios, linked ‘backwards’ to identify short-term ‘no regrets’ actions. The approach was designed by a team of climate scientists and policy practitioners in East Africa and tested in national and regional fora. Initial trials of the FCCP Framework has proved it to be popular and effective as a way of linking climate science with policy. Its use shows promise as a way of initiating discussions that can enable long-term climate change information to feed effectively into the policy and planning process.
DA - 2020/11//
PY - 2020/11//
DO - 10.1088/1748-9326/abbeb9
VL - 15
IS - 11
SP -
SN - 1748-9326
KW - climate change
KW - policy
KW - east Africa
KW - planning
KW - sanitation
KW - agriculture
KW - water
ER -
TY - JOUR
TI - The Global Sink of Available Potential Energy by Mesoscale Air-Sea Interaction
AU - Bishop, Stuart P.
AU - Small, R. Justin
AU - Bryan, Frank O.
T2 - JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
AB - The thermal component of oceanic eddy available potential energy (EPE) generation due to air-sea interaction is proportional to the product of anomalous sea surface temperature (SST) and net air-sea heat flux (SHF). In this study we assess EPE generation and its timescale and space-scale dependence from observations and a high-resolution coupled climate model. A dichotomy exists in the literature with respect to the sign of this term, that is, whether it is a source or a sink of EPE. We resolve this dichotomy by partitioning the SST and net heat flux into climatological mean, climatological seasonal cycle, and remaining transient contributions, thereby separating the mesoscale eddy variability from the forced seasonal cycle. In this decomposition the mesoscale air-sea SST-SHF feedbacks act as a 0.1 TW global sink of EPE. In regions of the ocean with a large seasonal cycle, for example, midlatitudes of the Northern Hemisphere, the EPE generation by the forced seasonal cycle exceeds the mesoscale variability sink, such that the global generation by seasonal plus eddy variability acts as a 0.8 TW source. EPE destruction is largest in the midlatitude western boundary currents due to mesoscale air-sea interaction and in the tropical Pacific where SST variability is due mainly to the El Niño-Southern Oscillation. The EPE sink in western boundary currents is spatially aligned with SST gradients and offset to the poleward side of currents, while the mean and seasonal generation are aligned with the warm core of the current. By successively smoothing the data in space and time we find that half of the EPE sink is confined to timescales less than annual and length scales less than 2°, within the oceanic mesoscale band.
DA - 2020/10//
PY - 2020/10//
DO - 10.1029/2020MS002118
VL - 12
IS - 10
SP -
SN - 1942-2466
ER -
TY - JOUR
TI - The controlling factors of high suspended sediment concentration in the intertidal flat off the Huanghe River Estuary
AU - Li, Bowen
AU - Jia, Yonggang
AU - Liu, J. Paul
AU - Su, Jianfeng
AU - Liu, Xiaolei
AU - Wen, Mingzheng
T2 - ACTA OCEANOLOGICA SINICA
DA - 2020/10//
PY - 2020/10//
DO - 10.1007/s13131-020-1679-9
VL - 39
IS - 10
SP - 96-106
SN - 1869-1099
KW - Huanghe River (Yellow River)
KW - sediment re-suspension
KW - sediment transport
KW - wave
KW - current
KW - in-situ observation
ER -
TY - JOUR
TI - Urban wind field analysis from the Jack Rabbit II Special Sonic Anemometer Study
AU - Pirhalla, Michael
AU - Heist, David
AU - Perry, Steven
AU - Hanna, Steven
AU - Mazzola, Thomas
AU - Arya, S. Pal
AU - Aneja, Viney
T2 - ATMOSPHERIC ENVIRONMENT
AB - The Jack Rabbit II Special Sonic Anemometer Study (JRII-S), a field project designed to examine the flow and turbulence within a systematically arranged mock-urban environment constructed from CONEX shipping containers, is described in detail. The study involved the deployment of 35 sonic anemometers at multiple heights and locations, including a 32 m tall, unobstructed tower located about 115 m outside the building array to document the approach wind flow characteristics. The purpose of this work was to describe the experimental design, analyze the sonic data, and report observed wind flow patterns within the urban canopy in comparison to the approaching boundary layer flow. We show that the flow within the building array follows a tendency towards one of three generalized flow regimes displaying channeling over a wide range of wind speeds, directions, and stabilities. Two or more sonic anemometers positioned only a few meters apart can have vastly different flow patterns that are dictated by the building structures. Within the building array, turbulence values represented by normalized vertical velocity variance ( σw2 ) are at least two to three times greater than that in the approach flow. There is also little evidence that σw2 measured at various heights or locations within the JRII array is a strong function of stability type in contrast to the approach flow. The results reinforce how urban areas create complicated wind patterns, channeling effects, and localized turbulence that can impact the dispersion of an effluent release. These findings can be used to inform the development of improved wind flow algorithms to better characterize pollutant dispersion in fast-response models.
DA - 2020/12/15/
PY - 2020/12/15/
DO - 10.1016/j.atmosenv.2020.117871
VL - 243
SP -
SN - 1873-2844
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85089852577&partnerID=MN8TOARS
KW - Jack rabbit II
KW - Turbulence
KW - Microscale meteorology
KW - Sonic anemometry
KW - Urban dispersion
KW - Building wakes
ER -
TY - JOUR
TI - Centennial clonal stability of asexual Daphnia in Greenland lakes despite climate variability
AU - Dane, Maison
AU - Anderson, Nicholas John
AU - Osburn, Christopher L.
AU - Colbourne, John K.
AU - Frisch, Dagmar
T2 - Ecology and Evolution
AB - Abstract Climate and environmental condition drive biodiversity at many levels of biological organization, from populations to ecosystems. Combined with paleoecological reconstructions, palaeogenetic information on resident populations provides novel insights into evolutionary trajectories and genetic diversity driven by environmental variability. While temporal observations of changing genetic structure are often made of sexual populations, little is known about how environmental change affects the long‐term fate of asexual lineages. Here, we provide information on obligately asexual, triploid Daphnia populations from three Arctic lakes in West Greenland through the past 200–300 years to test the impact of environmental change on the temporal and spatial population genetic structure. The contrasting ecological state of the lakes, specifically regarding salinity and habitat structure may explain the observed lake‐specific clonal composition over time. Palaeolimnological reconstructions show considerable regional environmental fluctuations since 1,700 (the end of the Little Ice Age), but the population genetic structure in two lakes was almost unchanged with at most two clones per time period. Their local populations were strongly dominated by a single clone that has persisted for 250–300 years. We discuss possible explanations for the apparent population genetic stability: (a) persistent clones are general‐purpose genotypes that thrive under broad environmental conditions, (b) clonal lineages evolved subtle genotypic differences unresolved by microsatellite markers, or (c) epigenetic modifications allow for clonal adaptation to changing environmental conditions. Our results motivate research into the mechanisms of adaptation in these populations, as well as their evolutionary fate in the light of accelerating climate change in the polar regions.
DA - 2020/12//
PY - 2020/12//
DO - 10.1002/ece3.7012
UR - https://doi.org/10.1002/ece3.7012
KW - asexual Daphnia
KW - egg bank
KW - Greenland
KW - lake sediment
KW - palaeogenetic
KW - palaeolimnology
ER -
TY - JOUR
TI - Assessing the manageable portion of ground-level ozone in the contiguous United States
AU - Luo, Huiying
AU - Astitha, Marina
AU - Rao, S. Trivikrama
AU - Hogrefe, Christian
AU - Mathur, Rohit
T2 - JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION
AB - Regional air quality models are widely being used to understand the spatial extent and magnitude of the ozone non-attainment problem and to design emission control strategies needed to comply with the relevant ozone standard through direct emission perturbations. In this study, we examine the manageable portion of ground-level ozone using two simulations of the Community Multiscale Air Quality (CMAQ) model for the year 2010 and a probabilistic analysis approach involving 29 years (1990-2018) of historical ozone observations. The modeling results reveal that the reduction in the peak ozone levels from total elimination of anthropogenic emissions within the model domain is around 13-21 ppb for the 90th-100th percentile range of the daily maximum 8-hr ozone concentrations across the contiguous United States (CONUS). Large reductions in the 4th highest 8-hr ozone are seen in the regions of West (interquartile range (IQR) of 17-33%), South (IQR 22-34%), Central (IQR 19-31%), Southeast (IQR 25-34%), and Northeast (IQR 24-37%). However, sites in the western portion of the domain generally show smaller reductions even when all anthropogenic emissions are removed, possibly due to the strong influence of global background ozone, including sources such as intercontinental ozone transport, stratospheric ozone intrusions, wildfires, and biogenic precursor emissions. Probabilistic estimates of the exceedances for several hypothetical thresholds of the 4th highest 8-hr ozone indicate that, in some areas, exceedances of such hypothetical thresholds may occur even with no anthropogenic emissions due to the ever-present atmospheric stochasticity and the current global tropospheric ozone burden. Implications: Because air pollution is intricately linked to adverse health effects, National Ambient Air Quality Standards (NAAQS) have been established for criteria pollutants to safeguard human health and the environment. Areas not in compliance with the relevant standards are required to develop plans and policies to reduce their air pollution levels. Regional-scale air quality models are currently being used routinely to inform policies to identify the emissions reduction required to meet and maintain the NAAQS throughout the country. This paper examines the feasibility of the 4th highest ozone, which is used to derive the ozone design value for NAAQS, complying with various current and hypothetical 8-hr ozone thresholds over CONUS based on the information embedded in 29 years of historical ozone observations and two modeling scenarios with and without anthropogenic emissions loading.
DA - 2020/11/1/
PY - 2020/11/1/
DO - 10.1080/10962247.2020.1805375
VL - 70
IS - 11
SP - 1136-1147
SN - 2162-2906
ER -
TY - BOOK
TI - HazMapper v1.0 source code
AU - Scheip, Corey
AU - Wegmann, Karl
DA - 2020/10/28/
PY - 2020/10/28/
DO - 10.5281/ZENODO.4103348
PB - Zenodo
UR - https://zenodo.org/record/4103348
ER -
TY - JOUR
TI - Highlighting recent trends in open source geospatial science and software
AU - Mobasheri, Amin
AU - Mitasova, Helena
AU - Neteler, Markus
AU - Singleton, Alexander
AU - Ledoux, Hugo
AU - Brovelli, Maria Antonia
T2 - TRANSACTIONS IN GIS
AB - Abstract Over the past decade, open source software has become widely accepted across governments, industries and academia. The geospatial domain is no exception and this trend is also reflected in geospatial research and practice. Nowadays, governments and stakeholders from the business sector both participate and promote open geospatial science including open geospatial data and open source geospatial software. As a result, open source geospatial science and software (i.e., open source GIS) is a growing area of research with numerous applications and great potential. The consistent prevalence of open source GIS studies motivated this thematic collection. The contributions are divided into two main categories. In the first, novel open source geospatial software and standards are presented, each of which has been implemented for and applied to a certain use case, and at the same time may be applied to other use cases due to the reproducibility of open source software. The second category presents and discusses the applicability and usability of open source GIS solutions for various interdisciplinary domains, mostly related to urban studies.
DA - 2020/10//
PY - 2020/10//
DO - 10.1111/tgis.12703
VL - 24
IS - 5
SP - 1141-1146
SN - 1467-9671
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85092776687&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Assessment of Numerical Simulations of Deep Circulation and Variability in the Gulf of Mexico Using Recent Observations
AU - Morey, Steven L.
AU - Gopalakrishnan, Ganesh
AU - Pallas Sanz, Enric
AU - Correia De Souza, Joao Marcos Azevedo
AU - Donohue, Kathleen
AU - Perez-Brunius, Paula
AU - Dukhovskoy, Dmitry
AU - Chassignet, Eric
AU - Cornuelle, Bruce
AU - Bower, Amy
AU - Furey, Heather
AU - Hamilton, Peter
AU - Candela, Julio
T2 - JOURNAL OF PHYSICAL OCEANOGRAPHY
AB - Abstract Three simulations of the circulation in the Gulf of Mexico (the “Gulf”) using different numerical general circulation models are compared with results of recent large-scale observational campaigns conducted throughout the deep (>1500 m) Gulf. Analyses of these observations have provided new understanding of large-scale mean circulation features and variability throughout the deep Gulf. Important features include cyclonic flow along the continental slope, deep cyclonic circulation in the western Gulf, a counterrotating pair of cells under the Loop Current region, and a cyclonic cell to the south of this pair. These dominant circulation features are represented in each of the ocean model simulations, although with some obvious differences. A striking difference between all the models and the observations is that the simulated deep eddy kinetic energy under the Loop Current region is generally less than one-half of that computed from observations. A multidecadal integration of one of these numerical simulations is used to evaluate the uncertainty of estimates of velocity statistics in the deep Gulf computed from limited-length (4 years) observational or model records. This analysis shows that the main deep circulation features identified from the observational studies appear to be robust and are not substantially impacted by variability on time scales longer than the observational records. Differences in strengths and structures of the circulation features are identified, however, and quantified through standard error analysis of the statistical estimates using the model solutions.
DA - 2020/4//
PY - 2020/4//
DO - 10.1175/JPO-D-19-0137.1
VL - 50
IS - 4
SP - 1045-1064
SN - 1520-0485
KW - Ocean circulation
KW - Abyssal circulation
KW - Bottom currents
KW - bottom water
KW - Eddies
KW - Ocean models
ER -
TY - JOUR
TI - Holocene paleoenvironmental changes in mud area southwest off Cheju Island, East China Sea: Evidence from benthic foraminiferal assemblages and stable isotope records
AU - Wang, Haoyin
AU - Zhang, Lanlan
AU - Xiang, Rong
AU - Liu, J. Paul
AU - Zhong, Fuchang
AU - Qiao, Shuqing
AU - Yang, Zuosheng
T2 - MARINE GEOLOGY
AB - A sediment core retrieved from the mud area southwest off Cheju Island (MASCI) was analysed for benthic foraminifera, grain size, and stable isotopes and constrained by AMS14C dating. Holocene paleoenvironmental changes in this broad shallow shelf were investigated, with special focus on the evolution of the MASCI and its related ocean eddy system. The results indicate that the East China Sea shelf has undergone four major environmental evolution stages during the Holocene. Prior to 9.8 cal. Kyr BP, the benthic foraminiferal assemblages were dominated by low salinity, shallow-water species [Ammonia beccarii (Linnaeus), Elphidium advenum (Cushman), and Cribrononion subincertum (Asano)], reflecting a near-coast-deposit environment. A noticeable transition of the benthic foraminifera, from an A. beccarii dominated to Ammonia compressiuscula (Brady) dominated assemblage, taking place at approximately 9.8 cal. Kyr BP together with a contemporaneous increase in δ18O and δ13C, provides evidence that a rapid rise in sea level occurred at this time in the East China Shelf. A gradual increase in δ18O between 9.8 and 6 cal. Kyr BP indicates a steady strengthening influence of open ocean water on the area under study. A sudden increase in the abundance of benthic foraminifera along with a decrease in the coarse fraction imply that an early eddy circulation system was established since almost 6 cal. Kyr BP in the MASCI. This eddy circulation system was quite weak but gradually strengthened between 6 and 3 cal. Kyr BP, possibly due to the intrusion of the Yellow Sea Warm Current (YSWC). A more stable mud deposition period, characterised by a high sedimentation rate of fine-grained sediment and lighter value of δ13C, starting at approximately 3 cal. Kyr BP, indicates that the MASCI was formed mainly during the late Holocene. We believe that the strengthened YSWC since 3 cal. Kyr BP might increase the trap efficiency of the eddy system, thereby accounting for the high sedimentation rate of mud deposits during this period.
DA - 2020/11//
PY - 2020/11//
DO - 10.1016/j.margeo.2020.106319
VL - 429
SP -
SN - 1872-6151
KW - Mud deposit
KW - Yellow Sea warm current
KW - East China Sea
KW - Benthic foraminifera
KW - Holocene
KW - Oxygen and carbon isotope
ER -
TY - JOUR
TI - Lithology, topography, and spatial variability of vegetation moderate fluvial erosion in the south-central Andes
AU - Seagren, Erin G.
AU - Schoenbohm, Lindsay M.
AU - Owen, Lewis A.
AU - Figueiredo, Paula M.
AU - Hammer, Sarah J.
AU - Rimando, Jeremy M.
AU - Wang, Yang
AU - Bohon, Wendy
T2 - EARTH AND PLANETARY SCIENCE LETTERS
AB - Understanding how tectonics, climate and lithology interact to control fluvial erosion is complicated because these factors are spatially-variable and they may not be well-represented by mean values. We address these complications using eight new and 54 published 10Be catchment-wide fluvial erosion rates from the south-central Andes. We assess how tectonics, climate, lithology, and topography control erosion through bivariate and multivariate Bayesian regression analysis. We first compare catchment-wide mean values of independent variables compared to other summary statistics and find that metrics that capture extreme values (e.g., 90th percentile) and spatial variability (e.g., 90th minus 10th percentile) produce stronger correlations. This suggests that catchment-wide means may oversimplify the roles of tectonics, climate, and lithology in influencing erosion rates. We find that the overall variability of erosion rates in the south-central Andes is best explained by a combination of lithologic resistance and spatial variability in both vegetation (using the normalized difference vegetation index, NDVI) and topography (using specific stream power). Despite poor bivariate correlations, both lithologic resistance and spatial variability of specific stream power are significant regressors in our multivariate modeling. Lithology influences the relationship (i.e., linearity) between topography and erosion rates. Spatial variability of NDVI produces the strongest correlation with erosion rates of any of the variables we consider. Hence, spatial variability of NDVI both accounts for potential non-uniform vegetation responses to climate and also incorporates the role of both humid climates (high 90th percentile) and large bare regions (low 10th percentile) within a single catchment.
DA - 2020/12/1/
PY - 2020/12/1/
DO - 10.1016/j.epsl.2020.116555
VL - 551
SP -
SN - 1385-013X
KW - fluvial erosion
KW - Central Andes
KW - Be-10 terrestrial cosmogenic nuclides vegetation
KW - Bayesian regression
ER -
TY - JOUR
TI - Quantification of Eruption Dynamics on the North Rift at Axial Seamount, Juan de Fuca Ridge
AU - Le Saout, M.
AU - Bohnenstiehl, D. R.
AU - Paduan, J. B.
AU - Clague, D. A.
T2 - GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
AB - Abstract Quantifying eruption dynamics in submarine environments is challenging. During the 2015 eruption of Axial Seamount, the formation of hummocky mounds along the north rift was accompanied by tens of thousands of impulsive acoustic signals generated by the interaction of lava and seawater. A catalog of these sounds was integrated with detailed seafloor mapping to better understand eruptive processes in time and space. Mounds grew over a period of 28 days with average extrusion rates of 22 to 45 m 3 s −1 . The most distant mounds, ~9.5 to 15.5 km down rift from the caldera, grew primarily over the first few days of the eruption. The focus of eruptive activity then retreated ~5 km toward the caldera where it was sustained. Mounds are constructed as a series of superimposed lobes formed through alternating periods of flow inflation, generating up to 30‐m‐thick hummocks, and periods of flow advancement, with <0.02 m s −1 average speeds typically observed.
DA - 2020/9//
PY - 2020/9//
DO - 10.1029/2020GC009136
VL - 21
IS - 9
SP -
SN - 1525-2027
ER -
TY - JOUR
TI - Geomorphometry and Statistical Analyses of Landslides Triggered by the 2015M(w)7.8 Gorkha Earthquake and theM(w)7.3 Aftershock, Nepal
AU - Tian, Yingying
AU - Owen, Lewis A.
AU - Xu, Chong
AU - Shen, Lingling
AU - Zhou, Qing
AU - Figueiredo, Paula Marques
T2 - FRONTIERS IN EARTH SCIENCE
AB - The 2015 Mw 7.8 Gorkha earthquake in Nepal and its Mw 7.3 aftershock triggered at least 22,914 landslides larger than 500 m2 in area and with lengths and widths longer than 20 m. Amongst these landslides, 2,059 had areas >10,000 m2. Analyses of the landslide geometry, using length (L), width (W), height (H, from the crown to toe), reach angle (arctan value of H/L), and aspect ratio (L/W), show that most of the landslides have aspect ratios of 1.6–3.6 and reach angles of 35–45°. The fitting relationship between H and L is H=0.87L-11.11. The steep topography is likely a main factor that controls the landslide runout and planar shape. Using the aspect ratio, these landslides are divided into three geomorphometric categories: LS1 (L/W≤2); LS2 (2
DA - 2020/9/18/
PY - 2020/9/18/
DO - 10.3389/feart.2020.572449
VL - 8
SP -
SN - 2296-6463
KW - 2015 Gorkha earthquake
KW - landslides
KW - Himalaya
KW - geometry
KW - planar geomorphometric shapes
KW - spatial distribution
ER -
TY - JOUR
TI - Evaluating the effects of regional climate trends along the West Antarctic Peninsula shelf based on the seabed distribution of naturally occurring radioisotopic tracers
AU - Taylor, Richard S.
AU - DeMaster, David J.
AU - Smith, Craig R.
AU - Thomas, Carrie J.
T2 - MARINE GEOLOGY
AB - Measurements of 230Th, 14C, 210Pb and 234Th activities were made on sediment cores collected along a N-S transect exhibiting a gradient in annual sea-ice duration off the West Antarctic Peninsula. The resultant data were used to evaluate the effects of regional warming on particle flux reaching the seabed on timescales from millennial to seasonal. Shelf samples were collected at five stations, over three cruises, between February 2008 and March 2009, as part of the FOODBANCS2 Project. Sea-ice conditions (the number of days ice-free prior to core collection) were evaluated at the five stations to understand the relationship between ice abundance and particle/radionuclide flux. Based on the millennial tracer 14C, rates of sediment accumulation along the peninsula decrease southward, consistent with the observed sea-ice gradient. 230Th data provide additional evidence on millennial timescales that sediment focusing (i.e., lateral transport) occurs to a greater extent in the northern reaches of the study area compared to the southernmost stations. The distribution of steady-state, 210Pb flux to the seabed (representing centurial trends) displays a similar trend to 14C, showing higher radionuclide/particle flux in the northern study area (where sea-ice duration is diminished) and lower flux southward as sea-ice duration increases. Additionally, 210Pb data suggest that lateral transport plays an important role in the sediment distributions of this radiotracer on hundred-year timescales, which is explainable by the relatively short circulation times of peninsular waters relative to 210Pb's half-life. On seasonal and annual time scales, the distribution of steady-state 234Th flux to the seabed shows an increase in radionuclide flux at the southernmost stations. This increase in radionuclide flux on seasonal and annual time scales is consistent with the warming trend along the peninsula and the reduction in sea-ice duration over the past decade. A significant statistical relationship, however, could not be established between annual sea-ice free days and 234Th-derived particle flux to the seabed. The fluxes/distributions of long-lived particle-reactive tracers (14C, 230Th, and 210Pb) on the West Antarctic Peninsula shelf appear to be controlled primarily by the long-term pattern of increasing annual sea-ice duration in the southward direction, whereas the fluxes of the short-lived tracer (234Th) are consistent with the more recent decreases in sea-ice duration (associated with climate change) that have occurred over the past decade, primarily in the southern West Antarctic Peninsula stations.
DA - 2020/11//
PY - 2020/11//
DO - 10.1016/j.margeo.2020.106315
VL - 429
SP -
SN - 1872-6151
KW - Radiochemical flux
KW - Seabed
KW - Sea-ice
KW - Climate change
KW - Antarctica
ER -
TY - JOUR
TI - Observations of new particle formation, modal growth rates, and direct emissions of sub-10 nm particles in an urban environment
AU - Zimmerman, Alyssa
AU - Petters, Markus D.
AU - Meskhidze, Nicholas
T2 - ATMOSPHERIC ENVIRONMENT
AB - Ultrafine particles with diameters less than 100 nm suspended in the air are a topic of interest in air quality and climate sciences. Sub-10 nm particles are of additional interest due to their health effects and contribution to particle growth processes. Ambient measurements were carried out at North Carolina State University in Raleigh, NC between April to June 2019 and November 2019 to May 2020 to investigate the temporal variability of size distribution and number concentration of ultrafine particles. A mobile lab was deployed between March and May 2020 to characterize the spatial distribution of sub-10 nm particle number concentration. New particle formation and growth events were observed regularly. Also observed were direct emissions of sub-10 nm particles. Analysis against meteorological variables, gas-phase species, and particle concentrations show that the sub-10nm particles dominated number concentration during periods of low planetary boundary layer height, low solar radiation, and northeast winds. The spatial patterns observed during mobile deployments suggest that multiple temporally stable and spatially confined point sources of sub-10 nm particles are present within the city. These sources likely include the campus utility plants and the Raleigh-Durham International Airport. Additionally, the timing of data collection allowed for investigation of variations in the urban aerosol number size distribution due to reduced economic activity during the COVID-19 pandemic.
DA - 2020/12/1/
PY - 2020/12/1/
DO - 10.1016/j.atmosenv.2020.117835
VL - 242
SP -
SN - 1873-2844
KW - Urban aerosol
KW - New particle formation
KW - Sub-10 nm aerosol
KW - Air pollution
ER -
TY - JOUR
TI - Molecular tests support the viability of rare earth elements as proxies for fossil biomolecule preservation
AU - Ullmann, Paul V.
AU - Voegele, Kristyn K.
AU - Grandstaff, David E.
AU - Ash, Richard D.
AU - Zheng, Wenxia
AU - Schroeter, Elena R.
AU - Schweitzer, Mary H.
AU - Lacovara, Kenneth J.
T2 - SCIENTIFIC REPORTS
AB - Abstract The rare earth element (REE) composition of a fossil bone reflects its chemical alteration during diagenesis. Consequently, fossils presenting low REE concentrations and/or REE profiles indicative of simple diffusion, signifying minimal alteration, have been proposed as ideal candidates for paleomolecular investigation. We directly tested this prediction by conducting multiple biomolecular assays on a well-preserved fibula of the dinosaur Edmontosaurus from the Cretaceous Hell Creek Formation previously found to exhibit low REE concentrations and steeply-declining REE profiles. Gel electrophoresis identified the presence of organic material in this specimen, and subsequent immunofluorescence and enzyme-linked immunosorbant assays identified preservation of epitopes of the structural protein collagen I. Our results thereby support the utility of REE profiles as proxies for soft tissue and biomolecular preservation in fossil bones. Based on considerations of trace element taphonomy, we also draw predictions as to the biomolecular recovery potential of additional REE profile types exhibited by fossil bones.
DA - 2020/9/23/
PY - 2020/9/23/
DO - 10.1038/s41598-020-72648-6
VL - 10
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Aboveground carbon loss associated with the spread of ghost forests as sea levels rise
AU - Smart, Lindsey S.
AU - Taillie, Paul J.
AU - Poulter, Benjamin
AU - Vukomanovic, Jelena
AU - Singh, Kunwar K.
AU - Swenson, Jennifer J.
AU - Mitasova, Helena
AU - Smith, Jordan W.
AU - Meentemeyer, Ross K.
T2 - ENVIRONMENTAL RESEARCH LETTERS
AB - Abstract Coastal forests sequester and store more carbon than their terrestrial counterparts but are at greater risk of conversion due to sea level rise. Saltwater intrusion from sea level rise converts freshwater-dependent coastal forests to more salt-tolerant marshes, leaving ‘ghost forests’ of standing dead trees behind. Although recent research has investigated the drivers and rates of coastal forest decline, the associated changes in carbon storage across large extents have not been quantified. We mapped ghost forest spread across coastal North Carolina, USA, using repeat Light Detection and Ranging (LiDAR) surveys, multi-temporal satellite imagery, and field measurements of aboveground biomass to quantify changes in aboveground carbon. Between 2001 and 2014, 15% (167 km 2 ) of unmanaged public land in the region changed from coastal forest to transition-ghost forest characterized by salt-tolerant shrubs and herbaceous plants. Salinity and proximity to the estuarine shoreline were significant drivers of these changes. This conversion resulted in a net aboveground carbon decline of 0.13 ± 0.01 TgC. Because saltwater intrusion precedes inundation and influences vegetation condition in advance of mature tree mortality, we suggest that aboveground carbon declines can be used to detect the leading edge of sea level rise. Aboveground carbon declines along the shoreline were offset by inland aboveground carbon gains associated with natural succession and forestry activities like planting (2.46 ± 0.25 TgC net aboveground carbon across study area). Our study highlights the combined effects of saltwater intrusion and land use on aboveground carbon dynamics of temperate coastal forests in North America. By quantifying the effects of multiple interacting disturbances, our measurement and mapping methods should be applicable to other coastal landscapes experiencing saltwater intrusion. As sea level rise increases the landward extent of inundation and saltwater exposure, investigations at these large scales are requisite for effective resource allocation for climate adaptation. In this changing environment, human intervention, whether through land preservation, restoration, or reforestation, may be necessary to prevent aboveground carbon loss.
DA - 2020/10//
PY - 2020/10//
DO - 10.1088/1748-9326/aba136
VL - 15
IS - 10
SP -
SN - 1748-9326
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85092484857&partnerID=MN8TOARS
KW - ghost forests
KW - sea level rise
KW - saltwater intrusion
KW - LiDAR
KW - aboveground carbon
ER -
TY - JOUR
TI - Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material
AU - Petters, Markus
AU - Kasparoglu, Sabin
T2 - SCIENTIFIC REPORTS
AB - Abstract Atmospheric aerosols can assume liquid, amorphous semi-solid or glassy, and crystalline phase states. Particle phase state plays a critical role in understanding and predicting aerosol impacts on human health, visibility, cloud formation, and climate. Melting point depression increases with decreasing particle diameter and is predicted by the Gibbs–Thompson relationship. This work reviews existing data on the melting point depression to constrain a simple parameterization of the process. The parameter $$\xi $$ ξ describes the degree to which particle size lowers the melting point and is found to vary between 300 and 1800 K nm for a wide range of particle compositions. The parameterization is used together with existing frameworks for modeling the temperature and RH dependence of viscosity to predict the influence of particle size on the glass transition temperature and viscosity of secondary organic aerosol formed from the oxidation of $$\alpha $$ α -pinene. Literature data are broadly consistent with the predictions. The model predicts a sharp decrease in viscosity for particles less than 100 nm in diameter. It is computationally efficient and suitable for inclusion in models to evaluate the potential influence of the phase change on atmospheric processes. New experimental data of the size-dependence of particle viscosity for atmospheric aerosol mimics are needed to thoroughly validate the predictions.
DA - 2020/9/16/
PY - 2020/9/16/
DO - 10.1038/s41598-020-71490-0
VL - 10
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Cosmogenic 10Be and 36Cl geochronology of cryoplanation terraces in the Alaskan Yukon-Tanana Upland
T2 - Quaternary Research
AB - ABSTRACT Cryoplanation terraces are prominent but enigmatic landforms found in present and past periglacial environments. Geomorphologists have debated for more than a century over processes involved in the formation of these elevated, step-like, bedrock features. Presented here are the first numerical surface exposure ages and scarp retreat rates from cryoplanation terraces in the Yukon-Tanana Upland (YTU) in Alaska, part of unglaciated eastern Beringia, obtained from terrestrial cosmogenic nuclides (TCN) in surface boulders. Ages comprise six 10 Be TCN ages from two terrace treads near Eagle Summit and six 36 Cl ages from two treads on Mt. Fairplay. Based on these exposure ages, scarps at both locations were last actively eroding from 49 to 22.4 ka. Both locations exhibit time-transgressive development, particularly near scarp-tread junctions. Boulder exposure ages and distances between sampled boulder locations were used to estimate scarp retreat rates of 0.11 to 0.56 cm/yr. These numerical exposure ages presented here demonstrate that the cryoplanation terraces in the YTU are diachronous surfaces actively eroding during multiple cold intervals. With these results, hypotheses for cryoplanation terrace formation are discussed and evaluated for the YTU, including those based on geologic structure, nivation, and the influence of permafrost.
DA - 2020/5/14/
PY - 2020/5/14/
DO - 10.1017/qua.2020.25
UR - http://dx.doi.org/10.1017/qua.2020.25
KW - Cryoplanation terraces
KW - Nivation
KW - Cosmogenic exposure dating
KW - Beringia
KW - Alaska
ER -
TY - JOUR
TI - Time‐Invariant Late Quaternary Slip Rates Along the Agua Blanca Fault, northern Baja California, Mexico
AU - Gold, P. O.
AU - Behr, W. M.
AU - Fletcher, J. M.
AU - Rockwell, T. K.
AU - Figueiredo, P. M.
T2 - Tectonics
AB - Abstract Fault slip rates inform models of strain accumulation and release, which over geologic time may vary or remain constant depending on factors like structural complexity, fault strength, deformation rates, and proximity to other faults. In this study, we present a Late Pleistocene–Holocene slip history based on four new geologic slip rates for the Agua Blanca Fault (ABF), which transfers Pacific‐North American dextral plate boundary motion across the Peninsular Ranges of northern Baja California. Time‐averaged slip rates from three sites are 2.8 + 0.8/−0.6 mm/a since ~65.1 ka, 3.0 + 1.4/−0.8 mm/a since ~21.8 ka, 3.2 + 1.0/−0.6 mm/a since ~12.5 ka, and 3.5 + 5.1/−2.0 mm/a since ~1.4 ka; however, the actual slip rate may be closer to 4 mm/a when off‐fault slip and age interpretation uncertainties are considered. Significantly, although the ABF has more in common in terms of length, net offset, and slip rate with known variable slip rate faults, the most straightforward age and offset interpretations for the ABF suggest constant slip rates over ~10 kyr time scales. As with other constant slip rate faults, comparable neighboring faults that might modulate the ABF slip rate are absent, suggesting that fault interaction, or lack thereof, may be a more significant factor controlling fault behavior on this and potentially other faults. The new rates indicate that the ABF accommodates at least half of total slip across the Peninsular Ranges, clarifying strain partitioning for seismic forecasting models that previously lacked modern geologic slip rate constraints for this domain of the plate boundary.
DA - 2020/8/4/
PY - 2020/8/4/
DO - 10.1029/2019tc005788
VL - 39
IS - 9
UR - http://dx.doi.org/10.1029/2019tc005788
KW - Agua Blanca Fault
KW - geologic slip rates
KW - fault slip history
KW - slip rate variability
KW - cosmogenic dating
KW - luminescence dating
ER -
TY - JOUR
TI - The Impact of MJO, Kelvin, and Equatorial Rossby Waves on the Diurnal Cycle over the Maritime Continent
AU - Worku, Lakemariam Y.
AU - Mekonnen, Ademe
AU - Schreck, Carl J., III
T2 - ATMOSPHERE
AB - The impacts of the Madden–Julian Oscillation (MJO), Kelvin waves, and Equatorial Rossby (ER) waves on the diurnal cycle of rainfall and types of deep convection over the Maritime Continent are investigated using rainfall from the Tropical Rainfall Measurement Mission Multisatellite Precipitation Analysis and Infrared Weather States (IR–WS) data from the International Satellite Cloud Climatology Project. In an absolute sense, the MJO produced its strongest modulations of rainfall and organized deep convection over the islands, when and where convection is already strongest. The MJO actually has a greater percentage modulation over the coasts and seas, but it does not affect weaker diurnal cycle there. Isolated deep convection was also more prevalent over land during the suppressed phase, while organized deep convection dominated the enhanced phase, consistent with past work. This study uniquely examined the effects of Kelvin and ER waves on rainfall, convection, and their diurnal cycles over the Maritime Continent. The modulation of convection by Kelvin waves closely mirrored that by the MJO, although the Kelvin wave convection continued farther into the decreasing phase. The signals for ER waves were also similar but less distinct. An improved understanding of how these waves interact with convection could lead to improved subseasonal forecast skill.
DA - 2020/7//
PY - 2020/7//
DO - 10.3390/atmos11070711
VL - 11
IS - 7
SP -
SN - 2073-4433
KW - MJO
KW - equatorial waves
KW - diurnal cycle
KW - convection
KW - Maritime Continent
ER -
TY - JOUR
TI - A Decade of Annual Arctic DOC Export With Polar Surface Water in the East Greenland Current
AU - Gonçalves‐Araujo, Rafael
AU - Stedmon, Colin A.
AU - Steur, Laura
AU - Osburn, Christopher L.
AU - Granskog, Mats A.
T2 - Geophysical Research Letters
AB - Abstract The export of dissolved organic carbon (DOC) from the Arctic Ocean is expected to change due to warming and increased river runoff. Here we present a method to quantify DOC transport with the East Greenland Current combining synoptic and year‐round data (2009–2018). An algorithm based on quantitative and qualitative aspects of colored dissolved organic matter (CDOM) was developed to provide DOC estimates. Combined with mooring‐derived monthly Polar Surface Water (PSW) volume transports, we estimate DOC exports for the period from 2003–2017. For much of the period DOC exports have been reasonably constant at 46.8 (±6.2) Tg yr −1 , while the reduction in PSW export in recent years has resulted in lower annual DOC exports (below 39 Tg C yr −1 ). We now have a technique to resolve seasonal and annual fluctuations in Arctic carbon export, offering a significant improvement over earlier bulk estimates and represents a baseline to detect future change.
DA - 2020/10/28/
PY - 2020/10/28/
DO - 10.1029/2020GL089686
UR - https://doi.org/10.1029/2020GL089686
KW - CDOM absorption slope
KW - current velocity
KW - volume transport
KW - ocean mooring
KW - Polar Surface Water
KW - Fram Strait
ER -
TY - JOUR
TI - Anatomy of the transgressive depositional system in a sediment-rich tide-dominated estuary: The paleo-Yangtze estuary, China
AU - Su, Jianfeng
AU - Fan, Daidu
AU - Liu, J. Paul
AU - Wu, Yijing
T2 - MARINE AND PETROLEUM GEOLOGY
AB - Sediment-rich tide-dominated estuary is generally considered nonexistent or ephemeral under the stable sea-level condition, given the rapid transition to a deltaic system after massive sediments dumping at the river mouth. The well-preserved transgressive sequence in the Yangtze paleo-valley represents an excellent location to examine the interplay between sediment supply, tide action, and sea-level change. To study the Yangtze paleo-valley geomorphological evolution and facies model, four 60-90-m long cores (YD0901, YD0902, YD0903, and CX03) were obtained. Lithological description, grain-size analysis, XRF core scanning, and AMS 14C dating were carried out. The results show that the Yangtze incised valley evolved from a river channel system (before 14.6 ka), through a tidal river (14.6-13 ka), and a tide-dominated estuary (13-8 ka), to a shallow marine (after 8 ka). The paleo-Yangtze estuary displays inner section dominated by muddy heterolithic deposition and the outer section occupied by mud-rich tidal bars and channels, distinctly differing from the well-down small estuaries with sand predominance. A fining-upward facies succession was produced by migration of mud-rich tidal bars in response to post-glacial sea-level rise. These bars are potentially the predecessor of tidal sand ridges on the East China Sea shelf after they were progressively abandoned during the post-glacial sea-level rise and exposed to tidal and storm-wave reworking. This is the first facies model developed from a sediment-rich tide-dominated estuary. This study provides a best example to study evolution of tide-dominated mega-river systems in response to the post-glacial transgression.
DA - 2020/11//
PY - 2020/11//
DO - 10.1016/j.marpetgeo.2020.104588
VL - 121
SP -
SN - 1873-4073
KW - Yangtze estuary
KW - Tide-dominated
KW - Sediment-rich
KW - Tidal bar
KW - Tidal sand ridge
KW - Facies model
ER -
TY - JOUR
TI - Fault Structure and Origin of Compressional Tectonic Features Within the Smooth Plains on Mercury
AU - Peterson, Georgia A.
AU - Johnson, Catherine L.
AU - Byrne, Paul K.
AU - Phillips, Roger J.
T2 - JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
AB - Abstract The major physiographic “smooth plains” units on Mercury are dominantly composed of volcanic deposits that have been deformed by horizontal compressive stresses. An open issue is whether these features formed by stresses induced by global contraction, bending stresses due to volcanic loading, or some combination of both. In this study, we model the surface expression of 12 shortening structures within several smooth plains units across Mercury to determine the geometries of the underlying faults. We implement an elastic dislocation model, using both listric and planar fault geometries, to place estimates on the depth of faulting for each feature. We show that a majority of smooth plains shortening structures penetrate the lithosphere to depths greater than 15 km. Thrust faults of this scale have not previously been recognized within the planet's smooth plains units and require a large horizontal stresses to form, which is best explained if this stress arises from global contraction. Further, our results suggest that the observed relief and length contrast between features in the smooth plains units and older intercrater plains units can be explained by interior layering of, and/or a shallower brittle‐ductile transition underlying, the smooth plains units.
DA - 2020/7//
PY - 2020/7//
DO - 10.1029/2019JE006183
VL - 125
IS - 7
SP -
SN - 2169-9100
KW - Mercury
KW - Planetary
KW - Planetary Tectonics
ER -
TY - JOUR
TI - Crustal Strength Variations Inferred From Earthquake Stress Drop at Axial Seamount Surrounding the 2015 Eruption
AU - Moyer, Pamela A.
AU - Boettcher, Margaret S.
AU - Bohnenstiehl, DelWayne R.
AU - Abercrombie, Rachel E.
T2 - GEOPHYSICAL RESEARCH LETTERS
AB - Abstract Variations in stress drops of earthquakes associated with the April and May 2015 eruption of Axial Seamount, on the Juan de Fuca Ridge, suggest a reduction in crustal strength as a result of the eruption. Seismicity during the inflation and deflation periods was well recorded by ocean bottom seismometers located within and along the caldera. We use these nearby recordings and an empirical Green's function spectral ratio method to obtain corner frequencies for stress drops of earthquakes on caldera ring faults. We find stress drops from 0.6 to 43 MPa for 423 ring fault earthquakes (1.6 ≤ M W ≤ 3.6) and an average stress drop two times higher during the inflation period (6.4 MPa) prior to the eruption, than during the subsequent deflation (3.2 MPa). Stress drops also correlate with spatially varying shear wave speed, possibly reflecting a region of pervasive cracking in the northern caldera.
DA - 2020/8/28/
PY - 2020/8/28/
DO - 10.1029/2020GL088447
VL - 47
IS - 16
SP -
SN - 1944-8007
KW - Seamount eruption
KW - submarine volcano
KW - caldera inflation deflation
KW - earthquake stress drop
KW - fault zone damage
KW - ocean bottom seismometers
ER -
TY - JOUR
TI - Quaternary Glaciation of the Himalaya and Adjacent Mountains
AU - Owen, Lewis A.
T2 - HIMALAYAN WEATHER AND CLIMATE AND THEIR IMPACT ON THE ENVIRONMENT
DA - 2020///
PY - 2020///
DO - 10.1007/978-3-030-29684-1_13
SP - 239-260
ER -
TY - JOUR
TI - Recent increases of rainfall and flooding from tropical cyclones (TCs) in North Carolina (USA): implications for organic matter and nutrient cycling in coastal watersheds
AU - Paerl, Hans W.
AU - Hall, Nathan S.
AU - Hounshell, Alexandria G.
AU - Rossignol, Karen L.
AU - Barnard, Malcolm A.
AU - Luettich, Richard A., Jr.
AU - Rudolph, Jacob C.
AU - Osburn, Christopher L.
AU - Bales, Jerad
AU - Harding, Lawrence W., Jr.
T2 - BIOGEOCHEMISTRY
AB - Coastal North Carolina experienced 36 tropical cyclones (TCs), including three floods of historical significance in the past two decades (Hurricanes Floyd-1999, Matthew-2016 and Florence-2018). These events caused catastrophic flooding and major alterations of water quality, fisheries habitat and ecological conditions of the Albemarle-Pamlico Sound (APS), the second largest estuarine complex in the United States. Continuous rainfall records for coastal NC since 1898 reveal a period of unprecedented high precipitation storm events since the late-1990s. Six of seven of the “wettest” storm events in this > 120-year record occurred in the past two decades, identifying a period of elevated precipitation and flooding associated with recent TCs. We examined storm-related freshwater discharge, carbon (C) and nutrient, i.e., nitrogen (N) and phosphorus (P) loadings, and evaluated contributions to total annual inputs in the Neuse River Estuary (NRE), a major sub-estuary of the APS. These contributions were highly significant, accounting for > 50% of annual loads depending on antecedent conditions and storm-related flooding. Depending on the magnitude of freshwater discharge, the NRE either acted as a “processor” to partially assimilate and metabolize the loads or acted as a “pipeline” to transport the loads to the APS and coastal Atlantic Ocean. Under base-flow, terrestrial sources dominate riverine carbon. During storm events these carbon sources are enhanced through the inundation and release of carbon from wetlands. These findings show that event-scale discharge plays an important and, at times, predominant role in C, N and P loadings. We appear to have entered a new climatic regime characterized by more frequent extreme precipitation events, with major ramifications for hydrology, cycling of C, N and P, water quality and habitat conditions in estuarine and coastal waters.
DA - 2020/9//
PY - 2020/9//
DO - 10.1007/s10533-020-00693-4
VL - 150
IS - 2
SP - 197-216
SN - 1573-515X
KW - Tropical cyclones
KW - Flooding
KW - Organic carbon
KW - Nutrient cycling
KW - Phytoplankton
KW - Estuarine
KW - Coastal
KW - North carolina
ER -
TY - JOUR
TI - Aircraft landing and takeoff emission impacts on surface O3 and PM2.5 through aerosol direct feedback effects estimated by the coupled WRF-CMAQ model
T2 - Atmospheric Environment
AB - The aerosol direct feedback effects (ADFEs) are neglected in traditional air quality modeling studies (where meteorology is used as input and not affected by the chemistry and aerosol microphysics) for estimating the impacts of aircraft emissions on air quality. In this study, aircraft landing and take-off (LTO) attributable change of O3 and PM2.5 concentrations through ADFEs for the year 2005 within the contiguous United States (CONUS) are quantified by a coupled meteorology-chemistry modeling system: Weather Research and Forecasting – Community Multi-scale Air Quality (WRF-CMAQ) model. We first quantified the effects of ADFEs of all aerosols within the CONUS (not the effects of aircraft LTO emissions) on surface meteorology and air quality and found that ADFEs changed on average the downward short-wave radiation (SWR), 2-m temperature (T2), planetary boundary layer (PBL) height, O3 and PM2.5 by −7.38 W/m2, −0.47 K, −20.72 m, −0.41 ppb and +0.28 μg/m3 in 2005. We also found a seasonal influence where ADFE-influenced change (decrease) of SWR, T2, PBL, O3 and change (increase) of PM2.5 were higher in summer than in winter. We found that the aircraft LTO emissions’ contribution to domain average surface concentration of O3 and PM2.5 were +0.0065 ppb and +0.0022 μg/m3 respectively when ADFEs are accounted for. The ADFEs decrease aircraft LTO attributable surface O3 and PM2.5 change by 21% and 23% respectively comparing with that without ADFE in 2005. We also found that in both without-and-with ADFE cases, the aircraft LTO emissions increases domain average of O3 from April to October and decreases from November to March showing a strong seasonal pattern. Our modeling study revealed that use of a coupled model with ADFE shows localized changes in air quality by aircraft LTO emissions across the domain which were masked when looking at domain averages for both O3 and PM2.5, and which may be important for accurately quantifying health risk due to air pollution exposures in densely populated areas.
DA - 2020/8//
PY - 2020/8//
DO - 10.1016/j.atmosenv.2020.117859
UR - http://dx.doi.org/10.1016/j.atmosenv.2020.117859
KW - Aircraft
KW - LTO
KW - Coupled WRF-CMAQ
KW - Aerosol feedback
ER -
TY - JOUR
TI - Supplementary material to "Limitations of WRF land surface models for simulating land use and land cover change in Sub-Saharan Africa and development of an improved model (CLM-AF v. 1.0)"
AU - Glotfelty, Timothy
AU - Ramírez-Mejía, Diana
AU - Bowden, Jared
AU - Ghilardi, Adrián
AU - West, J. Jason
DA - 2020/8/19/
PY - 2020/8/19/
DO - 10.5194/gmd-2020-193-supplement
VL - 8
UR - https://doi.org/10.5194/gmd-2020-193-supplement
ER -
TY - JOUR
TI - Limitations of WRF land surface models for simulating land use and land cover change in Sub-Saharan Africa and development of an improved model (CLM-AF v. 1.0)
AU - Glotfelty, Timothy
AU - Ramírez-Mejía, Diana
AU - Bowden, Jared
AU - Ghilardi, Adrián
AU - West, J. Jason
AB - Abstract. Land use and land cover change (LULCC) impacts local and regional climates through various biogeophysical processes. Accurate representation of land surface parameters in land surface models (LSMs) is essential to accurately predict these LULCC-induced climate signals. In this work, we test the applicability of the default Noah, Noah-MP, and CLM LSMs in the Weather Research and Forecasting Model (WRF) over Sub-Saharan Africa. We find that the default WRF LSMs do not accurately represent surface albedo, leaf area index, and surface roughness in this region due to various flawed assumptions, including the treatment of the MODIS woody savanna LULC category as closed shrubland. Consequently, we developed a WRF CLM version with more accurate African land surface parameters (CLM-AF), designed such that it can be used to evaluate the influence of LULCC. We evaluate meteorological performance for the default LSMs and CLM-AF against observational datasets, gridded products, and satellite estimates. Further, we conduct LULCC experiments with each LSM to determine if differences in land surface parameters impact the LULCC-induced climate signals. Despite clear deficiencies in surface parameters, all LSMs reasonably capture the spatial pattern and magnitude of near surface temperature and precipitation. However in the LULCC experiments, inaccuracies in the default LSMs result in illogical localized temperature and precipitation climate signals. Differences in thermal climate signals between Noah-MP and CLM-AF indicate that the temperature impacts from LULCC are dependent on the sensitivity of evapotranspiration to LULCC in Sub-Saharan Africa. Errors in land surface parameters indicate that the default WRF LSMs considered are not suitable for LULCC experiments in tropical or Southern Hemisphere regions, and that proficient meteorological model performance can mask these issues. We find CLM-AF to be suitable for use in Sub-Saharan Africa LULCC studies, but more work is needed by the WRF community to improve its applicability to other tropical and Southern Hemisphere climates.
DA - 2020/8/19/
PY - 2020/8/19/
DO - 10.5194/gmd-2020-193
VL - 8
UR - https://doi.org/10.5194/gmd-2020-193
ER -
TY - JOUR
TI - Anthropogenic Contaminants and Histopathological Findings in Stranded Cetaceans in the Southeastern United States, 2012-2018
AU - Page-Karjian, Annie
AU - Lo, Catherine F.
AU - Ritchie, Branson
AU - Harms, Craig A.
AU - Rotstein, David S.
AU - Han, Sushan
AU - Hassan, Sayed M.
AU - Lehner, Andreas F.
AU - Buchweitz, John P.
AU - Thayer, Victoria G.
AU - Sullivan, Jill M.
AU - Christiansen, Emily F.
AU - Perrault, Justin R.
T2 - FRONTIERS IN MARINE SCIENCE
AB - Anthropogenic contaminants in the marine environment often biodegrade slowly, bioaccumulate in organisms, and can have deleterious effects on wildlife immunity, health, reproduction, and development. In this study, we evaluated tissue toxicant concentrations and pathology data from 83 odontocetes that stranded in the southeastern United States during 2012–2018. Mass spectrometry was used to analyze blubber samples for five organic toxicants (atrazine, bisphenol-A, diethyl phthalates, nonylphenol monoethoxylate [NPE], triclosan), and liver samples were analyzed for five non-essential elements (arsenic, cadmium, lead, mercury, thallium), six essential elements (cobalt, copper, manganese, iron, selenium, zinc) and one toxicant mixture class (Aroclor1268). Resultant data considerably improve upon the existing knowledge base regarding toxicant concentrations in stranded odontocetes. Toxicant and element concentrations varied based on animal demographic factors including species, sex, age, and location. Samples from bottlenose dolphins had significantly higher average concentrations of lead, manganese, mercury, selenium, thallium, and zinc, and lower average concentrations of NPE, arsenic, cadmium, cobalt, and iron than samples from pygmy sperm whales. In adult female bottlenose dolphins, average arsenic concentrations were significantly higher and iron concentrations were significantly lower than in adult males. Adult bottlenose dolphins had significantly higher average concentrations of lead, mercury, and selenium, and significantly lower average manganese concentrations compared to juveniles. Dolphins that stranded in Florida had significantly higher average concentrations of lead, mercury, and selenium, and lower concentrations of iron than dolphins that stranded in North Carolina. Histopathological data are presented for 72 animals, including microscopic evidence of Campula spp. and Sarcocystis spp. infections, and results of Morbillivirus and Brucella spp. molecular diagnostic testing. Sublethal cellular changes related to toxicant exposure in free-ranging odontocetes may lead to health declines and, in combination with other factors, may contribute to stranding.
DA - 2020/8/5/
PY - 2020/8/5/
DO - 10.3389/fmars.2020.00630
VL - 7
SP -
SN - 2296-7745
KW - dolphins
KW - endocrine disrupting contaminants
KW - EDCs
KW - heavy metals
KW - mercury
KW - odontocete
KW - pathology
KW - toxicity
ER -
TY - JOUR
TI - Weakening aerosol direct radiative effects mitigate climate penalty on Chinese air quality
AU - Hong, Chaopeng
AU - Zhang, Qiang
AU - Zhang, Yang
AU - Davis, Steven J.
AU - Zhang, Xin
AU - Tong, Dan
AU - Guan, Dabo
AU - Liu, Zhu
AU - He, Kebin
T2 - NATURE CLIMATE CHANGE
AB - Future climate change may worsen air quality in many regions. However, evaluations of this ‘climate penalty’ on air quality have typically not assessed the radiative effects of changes in short-lived aerosols. Additionally, China’s clean air goals will decrease pollutant emissions and aerosol loadings, with concomitant weakening of aerosol feedbacks. Here we assess how such weakened aerosol direct effects alter the estimates of air pollution and premature mortality in China attributable to mid-century climate change under Representative Concentration Pathway 4.5. We found that weakening aerosol direct effects cause boundary layer changes that facilitate diffusion. This reduces air-pollution exposure (~4% in fine particulate matter) and deaths (13,800 people per year), which largely offset the additional deaths caused by greenhouse gas-dominated warming. These results highlight the benefits of reduced pollutant emissions through weakening aerosol direct effects and underline the potential of pollution control measures to mitigate climate penalties locked in by greenhouse gas emissions. Warming harms public health in Chinese cities directly via heat and indirectly by worsening air quality. Climate and epidemiological models estimate that reducing aerosols in a warmer climate can enhance atmospheric ventilation, reduce particulate matter exposure and offset warming-driven deaths.
DA - 2020/9//
PY - 2020/9//
DO - 10.1038/s41558-020-0840-y
VL - 10
IS - 9
SP - 845-+
SN - 1758-6798
ER -
TY - JOUR
TI - Tracking denudation and sediment production and transport with cosmogenic Be-10 in arid, high-altitude Himalayan half-grabens, Zanskar, northern India
AU - Dietsch, Craig
AU - Hedrick, Kathryn
AU - Owen, Lewis A.
AU - Caffee, Marc W.
T2 - EARTH SURFACE PROCESSES AND LANDFORMS
AB - Abstract Understanding the extent to which local factors, including bedrock and structure, govern catchment denudation in mountainous environments as opposed to broader climate or tectonic patterns provides insight into how landscapes evolve as sediment is generated and transported through them, and whether they have approached steady‐state equilibrium. We measured beryllium‐10 ( 10 Be) concentrations in 21 sediment samples from glaciated footwall and hanging wall catchments, including a set of nested catchments, and 12 bedrock samples in the Puga and Tso Morari half‐grabens located in the high‐elevation, arid Zanskar region of northern India. In the Puga half‐graben where catchments are underlain by quartzo‐feldspathic gneissic bedrock, bedrock along catchment divides is eroding very slowly, about 5 m/Ma, due to extreme aridity and 10 Be concentrations in catchment sediments are the highest (~60–90 × 10 5 atoms/g SiO 2 ) as colluvium accumulates on hillslopes, decoupled from their ephemeral streams. At Puga, 10 Be concentrations and the average erosion rates of a set of six nested catchments demonstrate that catchment denudation is transport‐limited as sediment stagnates on lower slopes before reaching the catchment outlet. In the Tso Morari half‐graben, gneissic bedrock is also eroding very slowly but 10 Be concentrations in sediments in catchments underlain by low grade meta‐sedimentary rocks, are significantly lower (~10–35 × 10 5 atoms/g SiO 2 ). In these arid, high‐elevation environments, 10 Be concentrations in catchment sediments have more to do with bedrock weathering and transport times than steady‐state denudation rates. © 2020 John Wiley & Sons, Ltd.
DA - 2020/10//
PY - 2020/10//
DO - 10.1002/esp.4954
VL - 45
IS - 13
SP - 3103-3119
SN - 1096-9837
KW - Zanskar
KW - Be-10 concentration
KW - catchment denudation
KW - bedrock erosion
KW - transport-limited
ER -
TY - JOUR
TI - Deposit-centered archaeological survey and the search for the Aegean Palaeolithic: A geoarchaeological perspective
AU - Holcomb, J. A.
AU - Runnels, Curtis
AU - Wegmann, Karl W.
T2 - QUATERNARY INTERNATIONAL
AB - Recent archaeological discoveries from the Greek islands of Crete and Naxos point to the presence of hominins in the Aegean Basin beginning at least in the Middle Pleistocene (~200 ka), indicating that the region may have been an important dispersal route for hominins (including humans) entering southeastern Europe. Currently, archaeologists lack a clear understanding about where Palaeolithic sites should exist throughout the region. Consequently, archaeologists are hindered in their ability to construct the chronostratigraphic frameworks necessary to place the Aegean Palaeolithic into broader narratives of human biogeography until more buried and scientifically dated sites are found. Addressing this issue, we review one successful survey strategy that has proven effective in increasing the likelihood of discovering archaeological sites of Pleistocene age – namely, systematic geoarchaeologically informed research frameworks centered on targeting Pleistocene geologic deposits (soils and sediments). Such an approach has worked well on mainland Greece (and elsewhere) but has yet to be operationalized for application in the Greek islands. Here we review the approach and suggest that deposit-centered surveys can function in four phases of varying degrees of complexity and scale and can be implemented either independently or in tandem with traditional archaeological pedestrian surveys. We also review Quaternary deposits and their associated geomorphic settings that are likely to contain Palaeolithic artifacts to aid future deposit-centered surveys in the Greek islands. We conclude that future archaeologists should implement the approach to target depositional settings in near-shore coastal areas (e.g., alluvial fans with stratified Pleistocene-aged paleosols), sometimes identified by paleo-sea-level-indicators (sea notches, marine terraces, and aeolianites), such as those seen on, Antiparos, Kythera, Crete (northern and southern coasts), Karpathos, and Rhodes. Further, we argue that non-coastal geomorphic settings like internally-drained basins on Crete and Rhodes, similar to those on the mainland, should be systematically searched for Palaeolithic sites. The deposit-centered survey strategies reviewed here provide a means for archaeologists working in the Aegean Basin to predict high probability locations for Palaeolithic archaeological sites. This geoarchaeological approach can be used in similar geomorphic settings around the world and therefore has implications for filling geographic gaps in our understanding of hominin dispersals in the Pleistocene.
DA - 2020/6/10/
PY - 2020/6/10/
DO - 10.1016/j.quaint.2020.04.043
VL - 550
SP - 169-183
SN - 1873-4553
UR - https://doi.org/10.1016/j.quaint.2020.04.043
KW - Geoarchaeology
KW - Palaeolithic archaeology
KW - Archaeological survey
KW - Sea-level change
KW - Pleistocene
KW - Aegean basin
ER -
TY - JOUR
TI - Geospatial simulation steering for adaptive management
AU - Petrasova, Anna
AU - Gaydos, Devon A.
AU - Petras, Vaclav
AU - Jones, Chris M.
AU - Mitasova, Helena
AU - Meentemeyer, Ross K.
T2 - Environmental Modelling & Software
AB - Spatio-temporal simulations are becoming essential tools for decision makers when forecasting future conditions and evaluating effectiveness of alternative decision scenarios. However, lack of interactive steering capabilities limits the value of advanced stochastic simulations for research and practice. To address this gap we identified conceptual challenges associated with steering stochastic, spatio-temporal simulations and developed solutions that better represent the realities of decision-making by allowing both reactive and proactive, spatially-explicit interventions. We present our approach, in a participatory modeling case study engaging stakeholders in developing strategies to contain the spread of a tree disease in Oregon, USA. Using intuitive interfaces, implemented through web-based and tangible platforms, stakeholders explored management options as the simulation progressed. Spatio-temporal steering allowed them to combine currently used management practices into novel adaptive management strategies, which were previously difficult to test and assess, demonstrating the utility of interactive simulations for decision-making.
DA - 2020/11//
PY - 2020/11//
DO - 10.1016/j.envsoft.2020.104801
VL - 133
SP - 104801
UR - https://doi.org/10.1016/j.envsoft.2020.104801
KW - Stochastic
KW - Participatory modeling
KW - Adaptive management
KW - Computational steering
KW - Forecasting
KW - Disease spread modeling
ER -
TY - JOUR
TI - The Impact of Kelvin Wave Activity during Dry and Wet African Summer Rainfall Years
AU - Mekonnen, Ademe
AU - Schreck, Carl J.
AU - Enyew, Bantwale D.
T2 - ATMOSPHERE
AB - This study highlights the influence of convectively coupled Kelvin wave (KW) activity on deep convection and African easterly waves (AEWs) over North Africa during dry and wet boreal summer rainfall years. Composite analysis based on 25 years of rainfall, satellite observed cold cloud temperature, and reanalysis data sets show that KWs are more frequent and stronger in dry Central African years compared with wet years. Deep convection associated with KWs is slightly more amplified in dry years compared with wet years. Further, KW activity over North Africa strengthens the lower level zonal flow and deepens the zonal moisture flux in dry years compared with wet years. Results also show that enhanced KW convection is in phase with above-average AEW variance in dry years. However, enhanced KW convection is out-of-phase with average AEW activity in wet years. In general, this study suggests that KW passage over Africa enhances convective activity and more strongly modulates the monsoon flow and moisture flux during the dry years than wet years.
DA - 2020/6//
PY - 2020/6//
DO - 10.3390/atmos11060568
VL - 11
IS - 6
SP -
SN - 2073-4433
KW - Kelvin waves
KW - African easterly waves
KW - African summer monsoon
ER -
TY - JOUR
TI - Observed Climatological Relationships of Extreme Daily Precipitation Events With Precipitable Water and Vertical Velocity in the Contiguous United States
AU - Kunkel, Kenneth E.
AU - Stevens, Scott E.
AU - Stevens, Laura E.
AU - Karl, Thomas R.
T2 - GEOPHYSICAL RESEARCH LETTERS
AB - Abstract An analysis of 3,104 stations in the United States shows virtually every station exhibits a positive correlation between precipitable water (PW) and extreme daily precipitation (EP) with over one‐third statistically significant. To first approximation, EP scales linearly with PW, but there is nonlinear scaling at the lower and upper ends of the PW distribution. On average, EP is amplified by twice the amount of PW, but there is substantial seasonal and spatial variability caused by dynamically forced vertical velocity with stations ranging from a one‐to‐one relationship to over three‐to‐one. These latter stations are generally found in elevated terrain or near coasts and in regions and seasons affected by strong synoptic‐scale weather systems. The results also point to PW, not vertical velocity, as the key limiting factor in the most intense EP events. This has important implications for projecting changes of the most intense EP events in a warmer world.
DA - 2020/6/28/
PY - 2020/6/28/
DO - 10.1029/2019GL086721
VL - 47
IS - 12
SP -
SN - 1944-8007
KW - precipitation
KW - extremes
KW - water vapor
ER -
TY - JOUR
TI - Acidification in the US Southeast: Causes, Potential Consequences and the Role of the Southeast Ocean and Coastal Acidification Network
AU - Hall, Emily R.
AU - Wickes, Leslie
AU - Burnett, Louis E.
AU - Scott, Geoffrey I
AU - Hernandez, Debra
AU - Yates, Kimberly K.
AU - Barbero, Leticia
AU - Reimer, Janet J.
AU - Baalousha, Mohammed
AU - Mintz, Jennifer
AU - Cai, Wei-Jun
AU - Craig, J. Kevin
AU - DeVoe, M. Richard
AU - Fisher, William S.
AU - Hathaway, Terri K.
AU - Jewett, Elizabeth B.
AU - Johnson, Zackary
AU - Keener, Paula
AU - Mordecai, Rua S.
AU - Noakes, Scott
AU - Phillips, Charlie
AU - Sandifer, Paul A.
AU - Schnetzer, Astrid
AU - Styron, Jay
T2 - FRONTIERS IN MARINE SCIENCE
AB - Coastal acidification in southeastern U.S. estuaries and coastal waters is influenced by biological activity, run-off from the land, and increasing carbon dioxide in the atmosphere. Acidification can negatively impact coastal resources such as shellfish, finfish, and coral reefs, and the communities that rely on them. Organismal responses for species located in the U.S. Southeast document large negative impacts of acidification, especially in larval stages. For example, the toxicity of pesticides increases under acidified conditions and the combination of acidification and low oxygen has profoundly negative influences on genes regulating oxygen consumption. In corals, the rate of calcification decreases with acidification and processes such as wound recovery, reproduction, and recruitment are negatively impacted. Minimizing the changes in global ocean chemistry will ultimately depend on the reduction of carbon dioxide emissions, but adaptation to these changes and mitigation of the local stressors that exacerbate global acidification can be addressed locally. The evolution of our knowledge of acidification, from basic understanding of the problem to the emergence of applied research and monitoring, has been facilitated by the development of regional Coastal Acidification Networks (CANs) across the United States. This synthesis is a product of the Southeast Coastal and Ocean Acidification Network (SOCAN). SOCAN was established to better understand acidification in the coastal waters of the U.S. Southeast and to foster communication among scientists, resource managers, businesses, and governments in the region. Here we review acidification issues in the U.S. Southeast, including the regional mechanisms of acidification and their potential impacts on biological resources and coastal communities. We recommend research and monitoring priorities and discuss the role SOCAN has in advancing acidification research and mitigation of and adaptation to these changes.
DA - 2020/7/10/
PY - 2020/7/10/
DO - 10.3389/fmars.2020.00548
VL - 7
SP -
SN - 2296-7745
UR - http://dx.doi.org/10.3389/fmars.2020.00548
KW - coastal acidification
KW - capacity-building
KW - stakeholders
KW - hypoxia
KW - shellfish
KW - crustaceans
KW - coral
ER -
TY - JOUR
TI - Physical controls and ENSO event influence on weathering in the Panama Canal Watershed
AU - Smith, Devin F.
AU - Goldsmith, Steven T.
AU - Harmon, Brendan A.
AU - Espinosa, Jorge A.
AU - Harmon, Russell S.
T2 - SCIENTIFIC REPORTS
AB - Abstract Recent empirical studies have documented the importance of tropical mountainous rivers on global silicate weathering and suspended sediment transport. Such field studies are typically based on limited temporal data, leaving uncertainty in the strength of observed relationships with controlling parameters over the long term. A deficiency of long-term data also prevents determination of the impact that multi-year or decadal climate patterns, such as the El Niño Southern Oscillation (ENSO), might have on weathering fluxes. Here we analyze an 18-year hydrochemical dataset for eight sub-basins of the Panama Canal Watershed of high-temporal frequency collected between 1998 and 2015 to address these knowledge gaps. We identified a strongly positive covariance of both cation (Ca 2+ , Mg 2+ , K + , Na + ) and suspended sediment yields with precipitation and extent of forest cover, whereas we observed negative relationships with temperature and mosaic landcover. We also confirmed a statistical relationship between seasonality, ENSO, and river discharge, with significantly higher values occurring during La Niña events. These findings emphasize the importance that long-term datasets have on identifying short-term influences on chemical and physical weathering rates, especially, in ENSO-influenced regions.
DA - 2020/7/2/
PY - 2020/7/2/
DO - 10.1038/s41598-020-67797-7
VL - 10
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Recent evolution of the Irrawaddy (Ayeyarwady) Delta and the impacts of anthropogenic activities: A review and remote sensing survey
AU - Chen, Dan
AU - Li, Xing
AU - Saito, Yoshiki
AU - Liu, J. Paul
AU - Duan, Yuangiang
AU - Liu, Shu'an
AU - Zhang, Lianpeng
T2 - GEOMORPHOLOGY
AB - Intensive studies have been conducted globally in the past decades to understand the evolution of several large deltas. However, despite being one of the largest tropical deltas, the Irrawaddy (Ayeyarwady) Delta has received relatively little attention from the research community. To reduce this knowledge gap, this study aims to provide a comprehensive assessment of the delta's evolution and identify its influencing factors using remote sensing images from 1974 to 2018, published literature and available datasets on the river, and human impacts in its drainage basin. Our results show that 1) Based on the topographic and geomorphological features, the funnel-shaped Irrawaddy Delta can be divided into two parts: the upper fluvial plain and the lower low-lying coastal plain; 2) The past 44-year shoreline changes show that overall accretion of the delta shoreline was at a rate of 10.4 m/year, and approximately 42% of the shoreline was subjected to erosion from 1974 to 2018. In the western coast, 60% of shoreline was under erosion with an average shoreline change rate of 0.1 m/year. In the east part, 81% of the shoreline was accreted with an average accretion rate of 24 m/year; 3) River channel geomorphological analysis indicates that three distributaries of the Irrawaddy, Bogale, and Toe have developed most active sandbars, which coincides with the amount of water they discharged (>50%). This implies that these three distributaries might be the currently most active channels in the delta; 4) The Irrawaddy mainstream in the Central Dry Zone (the original high sediment yield area) has become less braided and some tributaries have become increasingly straightened, which are highly likely related to reductions in sediment supply and peak flow induced by dam construction; 5) The large geomorphological adjustments at the two bifurcation points means that the diversions and fractions of water and sediment into the distributaries have likely already changed due to anthropogenic impacts. Our comprehensive analysis suggests that increasing human activities have caused reductions in coarse sediment supply entering the coastal delta plain, further inducing the erosion of the major channels in the lowermost delta and the western delta coast, and the adjustments of fluvial and coastal geomorphology; meanwhile, deforestation and terrestrial mining have provided extra fine sediment, which is mainly transported by the monsoon-driven current to the eastern coast to in part maintain its rapid accretion. Given the situation of rapidly increasing population and climate change, the current natural equilibrium state of the delta setting will most likely be disturbed in the near future. Therefore, our work calls for more intensive monitoring- and modeling-based study in order to better understand the controlling factors influencing the delta evolution in the future.
DA - 2020/9/15/
PY - 2020/9/15/
DO - 10.1016/j.geomorph.2020.107231
VL - 365
SP -
SN - 1872-695X
KW - Delta evolution
KW - Shoreline change
KW - Fluvial geomorphology
KW - Coastal geomorphology
KW - Remote sensing
KW - Human activities
ER -
TY - JOUR
TI - Centennial clonal stability of asexual Daphnia in Greenland lakes despite climate variability
AU - Dane, Maison
AU - Anderson, N. John
AU - Osburn, Christopher L.
AU - Colbourne, John K.
AU - Frisch, Dagmar
AB - Abstract Climate and environmental condition drive biodiversity at many levels of biological organisation, from populations to ecosystems. Combined with palaeoecological reconstructions, palaeogenetic information on resident populations provides novel insights into evolutionary trajectories and genetic diversity driven by environmental variability. While temporal observations of changing genetic structure are often made of sexual populations, little is known about how environmental change affects the long-term fate of asexual lineages. Here, we provide information on obligately asexual, triploid Daphnia populations from three Arctic lakes in West Greenland through the past 200-300 years to test the impact of a changing environment on the temporal and spatial population genetic structure. The contrasting ecological state of the lakes, specifically regarding salinity and habitat structure may explain the observed lake-specific clonal composition over time. Palaeolimnological reconstructions show considerable environmental fluctuations since 1700 (the end of the Little Ice Age), but the population genetic structure in two lakes was almost unchanged with at most two clones per time period. Their local populations were strongly dominated by a single clone that has persisted for 250-300 years. We discuss three possible explanations for the apparent population genetic stability: (1) the persistent clones are general purpose genotypes that thrive under broad environmental conditions, (2) clonal lineages evolved subtle genotypic differences that are unresolved by microsatellite markers, or (3) epigenetic modifications allow for clonal adaptation to changing environmental conditions. Our results will motivate research into the mechanisms of adaptation in these populations, as well as their evolutionary fate in the light of accelerating climate change in the polar regions.
DA - 2020/7/24/
PY - 2020/7/24/
DO - 10.1101/2020.07.22.208553
VL - 7
UR - https://doi.org/10.1101/2020.07.22.208553
ER -
TY - JOUR
TI - Measures of Canopy Structure from Low-Cost UAS for Monitoring Crop Nutrient Status
AU - Montgomery, Kellyn
AU - Henry, Josh B.
AU - Vann, Matthew C.
AU - Whipker, Brian E.
AU - Huseth, Anders S.
AU - Mitasova, Helena
T2 - DRONES
AB - Deriving crop information from remotely sensed data is an important strategy for precision agriculture. Small unmanned aerial systems (UAS) have emerged in recent years as a versatile remote sensing tool that can provide precisely-timed, fine-grained data for informing management responses to intra-field crop variability (e.g., nutrient status and pest damage). UAS sensors with high spectral resolution used to compute informative vegetation indices, however, are practically limited by high cost and data dimensionality. This research extends spectral analysis for remote crop monitoring to investigate the relationship between crop health and 3D canopy structure using low-cost UAS equipped with consumer-grade RGB cameras. We used flue-cured tobacco as a case study due to its known sensitivity to fertility variation and nutrient-specific symptomology. Fertilizer treatments were applied to induce plant health variability in a 0.5 ha field of flue-cured tobacco. Multi-view stereo images from three UAS surveys collected during crop development were processed into orthoimages used to compute a visible band spectral index and photogrammetric point clouds using Structure from Motion (SfM). Plant structural metrics were then computed from detailed high resolution canopy surface models (0.05 m resolution) interpolated from the photogrammetric point clouds. The UAS surveys were complimented by nutrient status measurements obtained from plant tissues. The relationships between foliar nitrogen (N), phosphorus (P), potassium (K), and boron (B) concentrations and the UAS-derived metrics were assessed using multiple linear regression. Symptoms of N and K deficiencies were well captured and differentiated by the structural metrics. The strongest relationship observed was between canopy shape and N foliar concentration (adj. r2 = 0.59, increasing to adj. r2 = 0.81 when combined with the spectral index). B foliar concentration was consistently better predicted by canopy structure with a maximum adj. r2 = 0.41 observed at the latest growth stage surveyed. Overall, combining information about canopy structure and spectral reflectance increased model fit for all measured nutrients compared to spectral alone. These results suggest that an important relationship exists between relative canopy shape and crop health that can be leveraged to improve the usefulness of low cost UAS for precision agriculture.
DA - 2020/9//
PY - 2020/9//
DO - 10.3390/drones4030036
VL - 4
IS - 3
SP -
SN - 2504-446X
UR - https://doi.org/10.3390/drones4030036
KW - unmanned aerial systems
KW - precision agriculture
KW - canopy structure
KW - crop surface model
KW - visible band index
KW - flue-cured tobacco
ER -
TY - JOUR
TI - High Resolution Viewscape Modeling Evaluated Through Immersive Virtual Environments
AU - Tabrizian, Payam
AU - Petrasova, Anna
AU - Baran, Perver
AU - Vukomanovic, Jelena
AU - Mitasova, Helena
AU - Meentemeyer, Ross
T2 - ISPRS International Journal of Geo-Information
AB - Visual characteristics of urban environments influence human perception and behavior, including choices for living, recreation and modes of transportation. Although geospatial visualizations hold great potential to better inform urban planning and design, computational methods are lacking to realistically measure and model urban and parkland viewscapes at sufficiently fine-scale resolution. In this study, we develop and evaluate an integrative approach to measuring and modeling fine-scale viewscape characteristics of a mixed-use urban environment, a city park. Our viewscape approach improves the integration of geospatial and perception elicitation techniques by combining high-resolution lidar-based digital surface models, visual obstruction, and photorealistic immersive virtual environments (IVEs). We assessed the realism of our viewscape models by comparing metrics of viewscape composition and configuration to human subject evaluations of IVEs across multiple landscape settings. We found strongly significant correlations between viewscape metrics and participants’ perceptions of viewscape openness and naturalness, and moderately strong correlations with landscape complexity. These results suggest that lidar-enhanced viewscape models can adequately represent visual characteristics of fine-scale urban environments. Findings also indicate the existence of relationships between human perception and landscape pattern. Our approach allows urban planners and designers to model and virtually evaluate high-resolution viewscapes of urban parks and natural landscapes with fine-scale details never before demonstrated.
DA - 2020/7/17/
PY - 2020/7/17/
DO - 10.3390/ijgi9070445
VL - 9
IS - 7
SP - 445
UR - https://doi.org/10.3390/ijgi9070445
KW - landscape
KW - lidar
KW - viewshed
KW - urban design
KW - urban planning
KW - geospatial
KW - perception
KW - virtual reality
ER -
TY - JOUR
TI - Introduction to the 50(th)Anniversary Issue of Quaternary Research
AU - Booth, Derek B.
AU - Gillespie, Alan R.
AU - Lancaster, Nicholas
AU - Owen, Lewis A.
T2 - QUATERNARY RESEARCH
AB - An abstract is not available for this content. As you have access to this content, full HTML content is provided on this page. A PDF of this content is also available in through the ‘Save PDF’ action button.
DA - 2020/7//
PY - 2020/7//
DO - 10.1017/qua.2020.35
VL - 96
SP - 1-21
SN - 1096-0287
ER -
TY - JOUR
TI - Viewshed simulation and optimization for digital terrain modelling with terrestrial laser scanning
AU - Starek, Michael J.
AU - Chu, Tianxing
AU - Mitasova, Helena
AU - Harmon, Russell S.
T2 - INTERNATIONAL JOURNAL OF REMOTE SENSING
AB - The main objective of this study is the development of a simulation and optimization method for wide-area terrain mapping with terrestrial laser scanning (TLS). The problem can be stated as follows: given a prior digital surface model (DSM) of a region of interest (e.g. from airborne lidar or structure-from-motion photogrammetry), determine the minimum number of scan locations required to seamlessly scan the terrain in the region for a given scanner range and angular field-of-view (FOV). An optimization method for measurement setup is developed using multiple viewshed analysis and simulated annealing (SA) constrained by the system performance characteristics and survey specifications. The method is evaluated at a sediment and erosion control facility with hilly terrain by comparing random scan locations versus optimized three to six scan locations. Statistical results illustrate that average visibility for random sampling increases gradually with scan locations. However, random sampling clearly underperforms in terms of scan visibility relative to five or six optimized scan locations with an average visibility of 100%. Similar patterns in optimized scan locations demonstrate that certain terrain morphometry at the study site is an essential factor for TLS survey design. Finally, an optimized solution is compared to a brute-force manual solution for determining four scan locations for conducting surveys at the study site. Results show the effectiveness of the optimization method for selecting combinations of scan locations that enable more efficient TLS survey coverage over a wider terrain area compared to manual selection. Furthermore, results demonstrate the adaptability of the method to take into consideration different scan parameters and survey conditions, such as pre-determined scan locations that may be required (e.g. a survey control monument).
DA - 2020/8/17/
PY - 2020/8/17/
DO - 10.1080/01431161.2020.1752952
VL - 41
IS - 16
SP - 6409-6426
SN - 1366-5901
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85087281550&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Bioavailability and compositional changes of dissolved organic matter in urban headwaters
AU - Fork, Megan L.
AU - Osburn, Christopher L.
AU - Heffernan, James B.
T2 - Aquatic Sciences
DA - 2020/10//
PY - 2020/10//
DO - 10.1007/s00027-020-00739-7
VL - 82
IS - 4
UR - https://doi.org/10.1007/s00027-020-00739-7
KW - DOM
KW - Biodegradation
KW - Lability
KW - Urban stream
KW - CDOM
KW - Optical properties
ER -
TY - JOUR
TI - Petrophysical properties, mechanical behaviour, and failure modes of impact melt-bearing breccia (suevite) from the Ries impact crater (Germany)
AU - Heap, Michael J.
AU - Gilg, H. Albert
AU - Byrne, Paul K.
AU - Wadsworth, Fabian B.
AU - Reuschle, Thierry
T2 - ICARUS
AB - The physical properties and mechanical behaviour of impactites are an important parameter in fluid flow models and slope stability and landscape evolution assessments for heavily impacted planetary bodies. We first present porosity, permeability, Young's modulus, and uniaxial compressive strength measurements for three suevites from the Ries impact crater (Germany). Porosity ranges from 0.18 to 0.43, permeability from 5.8 × 10−16 to 5.1 × 10−14 m2, Young's modulus from 1.4 to 8.1 GPa, and uniaxial compressive strength from 7.3 to 48.6 MPa. To explore their mechanical behaviour, we performed triaxial deformation experiments on these samples at a range of confining pressures. The brittle–ductile transition for the lowest (0.25) and highest (0.38) porosity suevite samples was at a confining pressure of ~30 and ~10 MPa, respectively (corresponding to, for example, depths of ~1 and ~4 km on Mars, respectively). Microstructural observations show that the dominant deformation micromechanism during brittle deformation is microcracking, and during ductile deformation is distributed cataclastic pore collapse. We show that a theoretically grounded permeability model for welded granular media accurately captures the permeability of the studied suevites, and we use micromechanical models to glean insight as to their mechanical behaviour. Finally, we upscale our laboratory measurements to provide physical property values for length scales more relevant for large-scale models, and we compare these data with those for basalt (a lithology representative of the surface of the inner Solar System bodies). These analyses show how macroscopic fractures serve to increase the permeability and decrease the strength and Young's modulus of suevite and basalt. We also find, for example, that basalt can be a factor of 2–5 stronger than suevite in the shallow crust. Our study suggests, therefore, that the rock masses comprising older, bombarded crusts are substantially weaker and more porous and permeable than the younger plains material on these bodies. These findings should be considered in large-scale fluid flow modelling and when providing crustal strength estimates or slope stability assessments for planetary bodies on which protracted records of impact bombardment are preserved.
DA - 2020/10//
PY - 2020/10//
DO - 10.1016/j.icarus.2020.113873
VL - 349
SP -
SN - 1090-2643
KW - Suevite
KW - Porosity
KW - Strength
KW - Permeability
KW - Alteration
KW - Young's modulus
ER -
TY - JOUR
TI - Rationale for BepiColombo Studies of Mercury's Surface and Composition
AU - Rothery, David A.
AU - Massironi, Matteo
AU - Alemanno, Giulia
AU - Barraud, Oceane
AU - Besse, Sebastien
AU - Bott, Nicolas
AU - Brunetto, Rosario
AU - Bunce, Emma
AU - Byrne, Paul
AU - Capaccioni, Fabrizio
AU - Capria, Maria Teresa
AU - Carli, Cristian
AU - Charlier, Bernard
AU - Cornet, Thomas
AU - Cremonese, Gabriele
AU - D'Amore, Mario
AU - De Sanctis, M. Cristina
AU - Doressoundiram, Alain
AU - Ferranti, Luigi
AU - Filacchione, Gianrico
AU - Galluzzi, Valentina
AU - Giacomini, Lorenza
AU - Grande, Manuel
AU - Guzzetta, Laura G.
AU - Helbert, Joern
AU - Heyner, Daniel
AU - Hiesinger, Harald
AU - Hussmann, Hauke
AU - Hyodo, Ryuku
AU - Kohout, Tomas
AU - Kozyrev, Alexander
AU - Litvak, Maxim
AU - Lucchetti, Alice
AU - Malakhov, Alexey
AU - Malliband, Christopher
AU - Mancinelli, Paolo
AU - Martikainen, Julia
AU - Martindale, Adrian
AU - Maturilli, Alessandro
AU - Milillo, Anna
AU - Mitrofanov, Igor
AU - Mokrousov, Maxim
AU - Morlok, Andreas
AU - Muinonen, Karri
AU - Namur, Olivier
AU - Owens, Alan
AU - Nittler, Larry R.
AU - Oliveira, Joana S.
AU - Palumbo, Pasquale
AU - Pajola, Maurizio
AU - Pegg, David L.
AU - Penttila, Antti
AU - Politi, Romolo
AU - Quarati, Francesco
AU - Re, Cristina
AU - Sanin, Anton
AU - Schulz, Rita
AU - Stangarone, Claudia
AU - Stojic, Aleksandra
AU - Tretiyakov, Vladislav
AU - Vaisanen, Timo
AU - Varatharajan, Indhu
AU - Weber, Iris
AU - Wright, Jack
AU - Wurz, Peter
AU - Zambon, Francesca
T2 - SPACE SCIENCE REVIEWS
AB - Abstract BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury’s surface than the suite carried by NASA’s MESSENGER spacecraft. Moreover, BepiColombo’s data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER’s remarkable achievements. Furthermore, the geometry of BepiColombo’s orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping. We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury’s surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER’s more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution. We anticipate that the insights gained into Mercury’s geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury’s origin including the nature and original heliocentric distance of the material from which it formed.
DA - 2020/6/2/
PY - 2020/6/2/
DO - 10.1007/s11214-020-00694-7
VL - 216
IS - 4
SP -
SN - 1572-9672
KW - BepiColombo
KW - Mercury
KW - Volatiles
KW - Crust
KW - Tectonism
KW - Volcanism
ER -
TY - JOUR
TI - Modeling Spatiotemporal Patterns of Ecosystem Metabolism and Organic Carbon Dynamics Affecting Hypoxia on the Louisiana Continental Shelf
AU - Jarvis, Brandon M.
AU - Lehrter, John C.
AU - Lowe, Lisa L.
AU - Hagy, James D., III
AU - Wan, Yongshan
AU - Murrell, Michael C.
AU - Ko, Dong S.
AU - Penta, Bradley
AU - Gould, Richard W., Jr.
T2 - JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
AB - The hypoxic zone on the Louisiana Continental Shelf (LCS) forms each summer due to nutrient enhanced primary production and seasonal stratification associated with freshwater discharges from the Mississippi/Atchafalaya River Basin (MARB). Recent field studies have identified highly productive shallow nearshore waters as an important component of shelf-wide carbon production contributing to hypoxia formation. In this study we present results from a three-dimensional hydrodynamic-biogeochemical model named CGEM (Coastal Generalized Ecosystem Model) applied to quantify the spatial and temporal patterns of hypoxia, carbon production, respiration, and transport between nearshore and middle shelf regions where hypoxia is most prevalent. We first demonstrate that our simulations successfully reproduced spatial and temporal patterns of carbon production, respiration, and bottom-water oxygen gradients compared to field observations. We then used interannual simulations to identify transport of particulate organic carbon (POC) from nearshore areas where riverine organic matter and phytoplankton carbon production are greatest. The spatial disconnect between carbon production and respiration in our simulations was driven by westward and offshore POC flux, a pattern that supported heterotrophic respiration on the middle shelf where hypoxia is frequently observed. These results validate the importance of offshore carbon flux to hypoxia formation, particularly on the west shelf where hypoxic conditions are more variable.
DA - 2020/4//
PY - 2020/4//
DO - 10.1029/2019JC015630
VL - 125
IS - 4
SP -
SN - 2169-9291
KW - Louisiana Continental Shelf
KW - Hypoxia
KW - Primary Production
KW - Respiration
KW - Carbon
ER -
TY - JOUR
TI - A 50,000-year record of lake-level variations and overflow from Owens Lake, eastern California, USA
AU - Bacon, Steven N.
AU - Jayko, Angela S.
AU - Owen, Lewis A.
AU - Lindvall, Scott C.
AU - Rhodes, Edward J.
AU - Schumer, Rina A.
AU - Decker, David L.
T2 - QUATERNARY SCIENCE REVIEWS
AB - A continuous lake-level curve was constructed for Owens Lake, eastern California by integrating lake-core data and shoreline geomorphology with new wind-wave and sediment entrainment modeling of lake-core sedimentology. This effort enabled refinement of the overflow history and development of a better understanding of the effects of regional and global climate variability on lake levels of the paleo-Owens River system during the last 50,000 years. The elevations of stratigraphic sites, plus lake bottom and spillway positions were corrected for vertical tectonic deformation using a differential fault-block model to estimate the absolute hydrologic change of the watershed-lake system. New results include 14C dating of mollusk shells in shoreline deposits, plus post-IR-IRSL dating of a suite of five beach ridges and OSL dating of spillway alluvial and deltaic deposits in deep boreholes. Geotechnical data show the overflow area is an entrenched channel that had erodible sills composed of unconsolidated fluvial-deltaic and alluvial sediment at elevations of ∼1113–1165 m above mean sea level. Owens Lake spilled most of the time at or near minimum sill levels, controlled by a bedrock sill at ∼1113 m. Nine major transgressions at ∼40.0, 38.7, 23.3, 19.3, 15.6, 13.8, 12.8, 11.6, and 10.6 ka reached levels ∼10–45 m above the bedrock sill. Several major regressions at or below the bedrock sill from 36.9 to 28.5 ka, and at ∼17.8, 12.9, and 10.4–8.8 ka indicate little to no overflow during these times. The latest period of overflow occurred ∼10–20 m above the bedrock sill from ∼8.4 to 6.4 ka that was followed by closed basin conditions after ∼6.4 ka. Previous lake core age-depth models were revised by accounting for sediment compaction and using no reservoir correction for open basin conditions, thereby reducing discrepancies between Owens Lake shoreline and lake-core proxy records. The integrated analysis provides a continuous 50 ka lake-level record of hydroclimate variability along the south-central Sierra Nevada that is consistent with other shoreline and speleothem records in the southwestern U.S.
DA - 2020/6/15/
PY - 2020/6/15/
DO - 10.1016/j.quascirev.2020.106312
VL - 238
SP -
SN - 0277-3791
KW - Late Pleistocene
KW - Holocene
KW - Owens Lake
KW - Searles Lake
KW - Sierra Nevada
KW - Paleoclimatology
KW - Hydroclimatic variability
KW - Lake-level reconstruction
KW - Shorelines
ER -
TY - JOUR
TI - An Automated Seepage Meter for Streams and Lakes
AU - Solomon, D. Kip
AU - Humphrey, Eric
AU - Gilmore, Troy E.
AU - Genereux, David P.
AU - Zlotnik, Vitaly
T2 - WATER RESOURCES RESEARCH
AB - Abstract We describe a new automatic seepage meter for use in soft bottom streams and lakes. The meter utilizes a thin‐walled tube that is inserted into the streambed or lakebed. A hole in the side of the tube is fitted with an electric valve. Prior to the test, the valve is open and the water level inside the tube is the same as the water level outside the tube. The test starts with closure of the valve, and the water level inside the tube changes as it moves toward the equilibrium hydraulic head that exists at the bottom of the tube. The time rate of change of the water level immediately after the valve closes is a direct measure of the seepage rate ( q ). The meter utilizes a precision linear actuator and a conductance circuit to sense the water level to a precision of about ±0.1 mm. The meter can also provide an estimate of vertical hydraulic conductivity ( K v ) if data are collected for a characteristic time. The detection limit for q depends on the vertical hydraulic head gradient. For K v = 1 m/day, q of about 2 mm/day can be measured. Results from a laboratory sand tank show excellent agreement between measured and true q , and results from a field site are similar to values from calculations based on independent measurements of K v and vertical head gradients. The meter can provide rapid (30 min) q measurements for both gaining and losing systems and complements other methods for quantifying surface water groundwater interactions.
DA - 2020/4//
PY - 2020/4//
DO - 10.1029/2019WR026983
VL - 56
IS - 4
SP -
SN - 1944-7973
KW - seepage meter
KW - rapid seepage measurements
KW - automated measurements for several days
KW - water level measurement to 0
KW - 1 mm
ER -
TY - JOUR
TI - Representing the function and sensitivity of coastal interfaces in Earth system models
AU - Ward, Nicholas D.
AU - Megonigal, J. Patrick
AU - Bond-Lamberty, Ben
AU - Bailey, Vanessa L.
AU - Butman, David
AU - Canuel, Elizabeth A.
AU - Diefenderfer, Heida
AU - Ganju, Neil K.
AU - Goni, Miguel A.
AU - Graham, Emily B.
AU - Hopkinson, Charles S.
AU - Khangaonkar, Tarang
AU - Langley, J. Adam
AU - McDowell, Nate G.
AU - Myers-Pigg, Allison N.
AU - Neumann, Rebecca B.
AU - Osburn, Christopher L.
AU - Price, Rene M.
AU - Rowland, Joel
AU - Sengupta, Aditi
AU - Simard, Marc
AU - Thornton, Peter E.
AU - Tzortziou, Maria
AU - Vargas, Rodrigo
AU - Weisenhorn, Pamela B.
AU - Windham-Myers, Lisamarie
T2 - NATURE COMMUNICATIONS
AB - Abstract Between the land and ocean, diverse coastal ecosystems transform, store, and transport material. Across these interfaces, the dynamic exchange of energy and matter is driven by hydrological and hydrodynamic processes such as river and groundwater discharge, tides, waves, and storms. These dynamics regulate ecosystem functions and Earth’s climate, yet global models lack representation of coastal processes and related feedbacks, impeding their predictions of coastal and global responses to change. Here, we assess existing coastal monitoring networks and regional models, existing challenges in these efforts, and recommend a path towards development of global models that more robustly reflect the coastal interface.
DA - 2020/5/18/
PY - 2020/5/18/
DO - 10.1038/s41467-020-16236-2
VL - 11
IS - 1
SP -
SN - 2041-1723
ER -
TY - JOUR
TI - Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage
AU - Bailleul, Alida M.
AU - Zheng, Wenxia
AU - Horner, John R.
AU - Hall, Brian K.
AU - Holliday, Casey M.
AU - Schweitzer, Mary H.
T2 - NATIONAL SCIENCE REVIEW
AB - Abstract A histological ground-section from a duck-billed dinosaur nestling (Hypacrosaurus stebingeri) revealed microstructures morphologically consistent with nuclei and chromosomes in cells within calcified cartilage. We hypothesized that this exceptional cellular preservation extended to the molecular level and had molecular features in common with extant avian cartilage. Histochemical and immunological evidence supports in situ preservation of extracellular matrix components found in extant cartilage, including glycosaminoglycans and collagen type II. Furthermore, isolated Hypacrosaurus chondrocytes react positively with two DNA intercalating stains. Specific DNA staining is only observed inside the isolated cells, suggesting endogenous nuclear material survived fossilization. Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years.
DA - 2020/4//
PY - 2020/4//
DO - 10.1093/nsr/nwz206
VL - 7
IS - 4
SP - 815-822
SN - 2053-714X
KW - cartilage
KW - dinosaur
KW - nuclei
KW - chromosomes
KW - collagen II
KW - DNA markers
ER -
TY - JOUR
TI - Deciphering the evolution and forcing mechanisms of glaciation over the Himalayan-Tibetan orogen during the past 20,000 years
AU - Yan, Qing
AU - Owen, Lewis A.
AU - Zhang, Zhongshi
AU - Jiang, Nanxuan
AU - Zhang, Ran
T2 - EARTH AND PLANETARY SCIENCE LETTERS
AB - The evolution of past glaciations over the Himalayan-Tibetan orogen and their links with climate change remain elusive, partially owing to the immense scale of the orogen preventing the investigation of all areas. Numerical modeling aids in filling the gaps, verifying the geologic observations, and exploring forcing factors. Based on a transient climate-ice sheet simulation for the past 20 kyr, we demonstrate that the maximum extent of glaciation over the Himalayan-Tibetan orogen occurs around the last glacial maximum (LGM; defined here at ∼20 ka), with expanded ice caps and extensive valley glaciers and being equivalent to a fourfold/sixfold expansion of today's glacier area/volume. The glacier extent shrinks rapidly after the LGM and reaches the minimum around ∼8–7 ka, followed by a slight long-term advancing trend afterwards. Our results suggest a dominant role of summer temperature in controlling the overall trend of glacier response, with precipitation generally modulating the regional extent of glaciation. However, the timing and extent of glaciation in the simulations varies across the Himalayan-Tibetan orogen on millennial timescale, especially between the monsoon-influenced southern and westerly-influenced western parts, further confirming previous speculations based on glacial geologic records. Despite the uncertainties in the simulations and the discrepancy in glaciation between the simulations and the glacial geologic evidence (e.g., 10Be ages), our results provide additional clues on the relationship between climatic change and glacier response. In addition, the modeling aids in advancing our knowledge of the paleoglaciological history of the Himalayan-Tibetan orogen.
DA - 2020/7/1/
PY - 2020/7/1/
DO - 10.1016/j.epsl.2020.116295
VL - 541
SP -
SN - 1385-013X
KW - glaciation
KW - Himalayan-Tibetan orogen
KW - ice-sheet modeling
KW - LGM
ER -
TY - JOUR
TI - Characterization of Extreme Wave Conditions for Wave Energy Converter Design and Project Risk Assessment
AU - Neary, Vincent S.
AU - Ahn, Seongho
AU - Seng, Bibiana E.
AU - Allahdadi, Mohammad Nabi
AU - Wang, Taiping
AU - Yang, Zhaoqing
AU - He, Ruoying
T2 - JOURNAL OF MARINE SCIENCE AND ENGINEERING
AB - Best practices and international standards for determining n-year return period extreme wave (sea states) conditions allow wave energy converter designers and project developers the option to apply simple univariate or more complex bivariate extreme value analysis methods. The present study compares extreme sea state estimates derived from univariate and bivariate methods and investigates the performance of spectral wave models for predicting extreme sea states at buoy locations within several regional wave climates along the US East and West Coasts. Two common third-generation spectral wave models are evaluated, a WAVEWATCH III® model with a grid resolution of 4 arc-minutes (6–7 km), and a Simulating WAves Nearshore model, with a coastal resolution of 200–300 m. Both models are used to generate multi-year hindcasts, from which extreme sea state statistics used for wave conditions characterization can be derived and compared to those based on in-situ observations at National Data Buoy Center stations. Comparison of results using different univariate and bivariate methods from the same data source indicates reasonable agreement on average. Discrepancies are predominantly random. Large discrepancies are common and increase with return period. There is a systematic underbias for extreme significant wave heights derived from model hindcasts compared to those derived from buoy measurements. This underbias is dependent on model spatial resolution. However, simple linear corrections can effectively compensate for this bias. A similar approach is not possible for correcting model-derived environmental contours, but other methods, e.g., machine learning, should be explored.
DA - 2020/4//
PY - 2020/4//
DO - 10.3390/jmse8040289
VL - 8
IS - 4
SP -
SN - 2077-1312
KW - extreme significant wave height
KW - wave hindcast
KW - wave energy resource assessment
KW - WEC design
ER -
TY - JOUR
TI - The Quaternary landforms of the Buyuk Menderes Graben System: the southern Menderes Massif, western Anatolia, Turkey
AU - Ozpolat, Emrah
AU - Yildirim, Cengiz
AU - Gorum, Tolga
T2 - JOURNAL OF MAPS
AB - We present the first detailed Quaternary landform map of the Büyük Menderes Graben System, located in western Turkey which is one of the most active extensional domains in the world. The main map was produced with a combination of TanDEM-X (12.5 m resolution), Red Relief Image Map, unmanned aerial vehicle, Google Earth images, and multiple fieldworks. The main map is presented at a scale of 1:160,000 although landforms were mapped at a scale of 1:15,000. The ten Quaternary landforms were defined considering their surface morphology and depositional environment. The alluvial fans, river terraces, and floodplains are the most common landforms. The spatial pattern of the alluvial fans and river terraces showed the variable rates of tectonics and surface processes along the strike of the graben system. The distribution of the meander cut-offs and paleo-shorelines imply that Büyük Menderes Graben System is vulnerable to geohazards like flash-flood sedimentation and flood events.
DA - 2020/12/9/
PY - 2020/12/9/
DO - 10.1080/17445647.2020.1764874
VL - 16
IS - 2
SP - 405-419
SN - 1744-5647
KW - Extensional landscape
KW - alluvial fan
KW - river terrace
KW - Red Relief Image Map
KW - western Anatolia
KW - Menderes Massif
ER -
TY - JOUR
TI - Extracting the Buoyancy-Driven Atlantic Meridional Overturning Circulation
AU - Larson, Sarah M.
AU - Buckley, Martha W.
AU - Clement, Amy C.
T2 - JOURNAL OF CLIMATE
AB - Abstract Variations in the Atlantic meridional overturning circulation (AMOC) driven by buoyancy forcing are typically characterized as having a low-frequency time scale, interhemispheric structure, cross-equatorial heat transport, and linkages to the strength of Northern Hemisphere gyre circulations and the Gulf Stream. This study first tests whether these attributes ascribed to the AMOC are reproduced in a coupled model that is mechanically decoupled and, hence, is only buoyancy coupled. Overall, the mechanically decoupled model reproduces these attributes, with the exception that in the subpolar gyre, buoyancy drives AMOC variations on interannual to multidecadal time scales, yet only the multidecadal variations penetrate into the subtropics. A stronger AMOC is associated with a strengthening of the Northern Hemisphere gyre circulations, Gulf Stream, and northward oceanic heat transport throughout the basin. We then determine whether the characteristics in the mechanically decoupled model can be recovered by low-pass filtering the AMOC in a fully coupled version of the same model, a common approach used to isolate the buoyancy-driven AMOC. A major conclusion is that low-pass filtering the AMOC in the fully coupled model reproduces the buoyancy-driven AMOC pattern and most of the associated attributes, but not the statistics of the temporal variability. The strength of the AMOC–Gulf Stream connection is also not reproduced. The analyses reveal caveats that must be considered when choosing indexes and filtering techniques to estimate the buoyancy-driven AMOC. Results also provide insight on the latitudinal dependence of time scales and drivers of ocean circulation variability in coupled models, with potential implications for measurement and detection of the buoyancy-driven AMOC in the real world.
DA - 2020/6//
PY - 2020/6//
DO - 10.1175/JCLI-D-19-0590.1
VL - 33
IS - 11
SP - 4697-4714
SN - 1520-0442
KW - North Atlantic Ocean
KW - Meridional overturning circulation
KW - Atmosphere-ocean interaction
KW - Coupled models
KW - Multidecadal variability
ER -
TY - JOUR
TI - Effect of Wave, Current, and Lutocline on Sediment Resuspension in Yellow River Delta-Front
AU - Li, Bowen
AU - Jia, Yonggang
AU - Liu, J. Paul
AU - Liu, Xiaolei
AU - Wang, Zhenhao
T2 - WATER
AB - Historically, the Yellow River in China discharges > 1 × 109 ton/yr sediment to the sea, and has formed a large delta in the western Bohai Sea. Its river mouth is characterized by an extremely high suspended sediment concentration (SSC), up to 50 g/L. However, the hydrodynamic factors controlling the high suspended sediments in the Yellow River estuary are not well understood. Here, we conducted two hydrodynamic observations and SSC measurements in the winter and spring low-flow seasons of 2014–2015 and 2016–2017 under five sea conditions, including calm-rippled, smooth-wavelet, slight, moderate, and rough, in the Yellow River Delta-front during the observation period. Under calm-rippled conditions, the contribution of currents to the total resuspended sediment concentration (RSC) was 77.7%–100.0%. During the smooth-wavelet and slight periods, the currents’ contribution decreased as low as 30% and 3.0% of the total RSC, respectively. Under moderate and rough-sea conditions, waves accounted for at least 70% and 85% of the total RSC, respectively. The results indicate that 20 cm-thick lutoclines were created after a significant increase in the wave height to a peak value followed by a decrease. When the SSC is over 3 g/L and hydrodynamic conditions could not break the lutoclines, the flocculent settling of suspended sediment changes to hindered settling in the Yellow River Delta. Under hindered settling, the settling velocity decreases, and the resuspended sediments remains in the lutoclines and their lower water layers. This study reveals different controlling factors for the high SSC near a river-influenced delta, and helps us get a better understanding of a delta’s resuspension and settling mechanisms.
DA - 2020/3//
PY - 2020/3//
DO - 10.3390/w12030845
VL - 12
IS - 3
SP -
SN - 2073-4441
KW - sediment resuspension
KW - wave
KW - current
KW - lutoclines
KW - in-situ observation
ER -
TY - JOUR
TI - Revised Magmatic Source Models for the 2015 Eruption at Axial Seamount Including Estimates of Fault-Induced Deformation
AU - Hefner, William L.
AU - Nooner, Scott L.
AU - Chadwick, William W., Jr.
AU - Bohnenstiehl, DelWayne R.
T2 - JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
AB - Abstract Axial Seamount is an active submarine volcano located at the intersection of the Cobb hot spot and the Juan de Fuca Ridge (45°57′N, 130°01′W). Bottom pressure recorders captured co‐eruption subsidence of 2.4–3.2 m in 1998, 2011, and 2015, and campaign‐style pressure surveys every 1–2 years have provided a long‐term time series of inter‐eruption re‐inflation. The 2015 eruption occurred shortly after the Ocean Observatories Initiative (OOI) Cabled Array came online providing real‐time seismic and deformation observations for the first time. Nooner and Chadwick (2016, https://doi.org/10.1126/science.aah4666 ) used the available vertical deformation data to model the 2015 eruption deformation source as a steeply dipping prolate‐spheroid, approximating a high‐melt zone or conduit beneath the eastern caldera wall. More recently, Levy et al. (2018, https://doi.org/10.1130/G39978.1 ) used OOI seismic data to estimate dip‐slip motion along a pair of outward‐dipping caldera ring faults. This fault motion complicates the deformation field by contributing up to several centimeters of vertical seafloor motion. In this study, fault‐induced surface deformation was calculated from the slip estimates of Levy et al. (2018, https://doi.org/10.1130/G39978.1 ) then removed from vertical deformation data prior to model inversions. Removing fault motion resulted in an improved model fit with a new best‐fitting deformation source located 2.11 km S64°W of the source of Nooner and Chadwick (2016, https://doi.org/10.1126/science.aah4666 ) with similar geometry. This result shows that ring fault motion can have a significant impact on surface deformation, and future modeling efforts need to consider the contribution of fault motion when estimating the location and geometry of subsurface magma movement at Axial Seamount.
DA - 2020/4//
PY - 2020/4//
DO - 10.1029/2020JB019356
VL - 125
IS - 4
SP -
SN - 2169-9356
KW - Axial Seamount
KW - seafloor pressure
KW - ring faulting
KW - geodesy
KW - seismicity
ER -
TY - JOUR
TI - Storm Event Nitrogen Dynamics in Waterfowl Impoundments (vol 230, 294, 2019)
AU - Hinckley, B. R.
AU - Etheridge, J. R.
AU - Peralta, A. L.
T2 - WATER AIR AND SOIL POLLUTION
AB - The original version of this article unfortunately contained an error in the areas of the impoundments reported in Section 2.1 of the published article.
DA - 2020/5/2/
PY - 2020/5/2/
DO - 10.1007/s11270-020-04594-y
VL - 231
IS - 5
SP -
SN - 1573-2932
ER -
TY - JOUR
TI - A multi-scale model analysis of ozone formation in the Bangkok Metropolitan Region, Thailand
AU - Uttamang, Pornpan
AU - Campbell, Patrick C.
AU - Aneja, Viney P.
AU - Hanna, Adel F.
T2 - ATMOSPHERIC ENVIRONMENT
AB - Over the last three decades, Thailand's rapid industrialization and urbanization have led to an impact on urban air quality. A majority of the country's development has occurred within and around Bangkok (BKK), the capital city of Thailand, and the Bangkok Metropolitan Region (BMR). Since 1995, the BMR has experienced air quality degradation, in particular, enhanced ozone (O3) due to a combination of the local increase in emissions from accelerated growth in automotive and industrial activities, local meteorology including strong solar radiation, high temperature and high humidity, and potential long-range effects of regional transport from China. To investigate the O3 formation in the BMR due to the effects of long-range transport and local meteorology feedbacks, we perform a multi-scale simulation with the Weather Research and Forecasting model with Chemistry (WRF-Chem) during the O3 season (January to March), 2010; since O3 mixing ratio exceedances in the BMR occur primarily during this period The results in this study indicate the significance of China's emission reductions on the regional-scale and the local-scale pollution, as far as the BMR region and southern Thailand. Applying China's oxide of nitrogen (NOx)-only emission controls, generally, enhance the domain-wide monthly-average peroxyacetyl nitrate (PAN) and O3 in the regional scale, in the order of ~1–7% and ~1–5%, respectively, while those in the local scale are ~ 0.2–6% and ~0.1–5% compared with the baseline simulation. However, the increases in PAN and O3 are mitigated by 40% China's Volatile Organic Compound (VOC) reduction along with 40% NOx reduction. The results, supported by an indicator analysis, suggest that northern and eastern China, northern and central Thailand and the BMR, are likely VOC-limited during the O3 season. Since the BMR is VOC-limited regime, controlling anthropogenic VOC emissions will show more benefit to control O3 than controlling NOx-only emissions. Other factors that influence on O3 levels in the BMR are biogenic VOC emissions from the Tenasserim range and land- and sea-breeze circulations that recirculate and disperse pollutants along the coastal areas.
DA - 2020/5/15/
PY - 2020/5/15/
DO - 10.1016/j.atmosenv.2020.117433
VL - 229
SP -
SN - 1873-2844
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083337226&partnerID=MN8TOARS
KW - Long-range transport
KW - Surface ozone
KW - WRF-Chem
KW - VOC-Limited
KW - NOx limited
ER -
TY - JOUR
TI - Quantifying the Probability and Causes of the Surprisingly Active 2018 North Atlantic Hurricane Season
AU - Saunders, M. A.
AU - Klotzbach, P. J.
AU - Lea, A. S. R.
AU - Schreck, C. J.
AU - Bell, M. M.
T2 - EARTH AND SPACE SCIENCE
AB - Abstract The 2018 North Atlantic hurricane season was a destructive season with hurricanes Florence and Michael causing significant damage in the southeastern United States. In keeping with most destructive hurricane seasons, basinwide tropical cyclone activity was above average in 2018—by ~25% for named storm numbers, hurricane numbers, and Accumulated Cyclone Energy (ACE). In contrast to this above‐normal activity, the August–September tropical environmental fields that explain ~50% of the variance in Atlantic basin hurricane activity between 1950 and 2017 anticipated a well below‐average 2018 hurricane season. The surprisingly large mismatch between the observed and replicated levels of hurricane activity in 2018 is an extreme example of the uncertainty inherent in seasonal hurricane outlooks and highlights the need for these outlooks to be issued in terms of probability of exceedance. Such probabilistic information would better clarify the uncertainty associated with hurricane outlooks to the benefit of users. With retrospective knowledge of the August–September 2018 key tropical environmental fields, the chance that the observed 2018 Atlantic hurricane activity would occur is about 5%. The reasons for the surprisingly high hurricane activity in 2018 are a hurricane outbreak in early September and, in particular, the occurrence of unusually high tropical cyclone activity in the subtropical North Atlantic. The hyperactive subtropical activity was not anticipated because contemporary statistical models of seasonal Atlantic hurricane activity lack skill in anticipating subtropical ACE compared to tropical ACE.
DA - 2020/3//
PY - 2020/3//
DO - 10.1029/2019EA000852
VL - 7
IS - 3
SP -
SN - 2333-5084
ER -
TY - JOUR
TI - A call for refining the role of humic-like substances in the oceanic iron cycle
AU - Whitby, Hannah
AU - Planquette, Helene
AU - Cassar, Nicolas
AU - Bucciarelli, Eva
AU - Osburn, Christopher L.
AU - Janssen, David J.
AU - Cullen, Jay T.
AU - Gonzalez, Aridane G.
AU - Voelker, Christoph
AU - Sarthou, Geraldine
T2 - SCIENTIFIC REPORTS
AB - Abstract Primary production by phytoplankton represents a major pathway whereby atmospheric CO 2 is sequestered in the ocean, but this requires iron, which is in scarce supply. As over 99% of iron is complexed to organic ligands, which increase iron solubility and microbial availability, understanding the processes governing ligand dynamics is of fundamental importance. Ligands within humic-like substances have long been considered important for iron complexation, but their role has never been explained in an oceanographically consistent manner. Here we show iron co-varying with electroactive humic substances at multiple open ocean sites, with the ratio of iron to humics increasing with depth. Our results agree with humic ligands composing a large fraction of the iron-binding ligand pool throughout the water column. We demonstrate how maximum dissolved iron concentrations could be limited by the concentration and binding capacity of humic ligands, and provide a summary of the key processes that could influence these parameters. If this relationship is globally representative, humics could impose a concentration threshold that buffers the deep ocean iron inventory. This study highlights the dearth of humic data, and the immediate need to measure electroactive humics, dissolved iron and iron-binding ligands simultaneously from surface to depth, across different ocean basins.
DA - 2020/4/9/
PY - 2020/4/9/
DO - 10.1038/s41598-020-62266-7
VL - 10
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Fate of Ayeyarwady and Thanlwin Rivers Sediments in the Andaman Sea and Bay of Bengal
AU - Liu, J. Paul
AU - Kuehl, Steven A.
AU - Pierce, Austin C.
AU - Williams, Joshua
AU - Blair, Neal E.
AU - Harris, Courtney
AU - Aung, Day Wa
AU - Aye, Yin Yin
T2 - MARINE GEOLOGY
AB - Collectively, the modern Ayeyarwady (Irrawaddy) and Thanlwin (Salween) rivers deliver >600 Mt/yr of sediment to the sea. To understand the fate of Ayeyarwady and Thanlwin river-derived sediments to the sea, we conducted a 14-day geophysical and geological survey in the northern Andaman Sea and eastern Bay of Bengal in December 2017. Overall, ~1500-km of high-resolution Chirp-sonar profiles and 30 sediment cores from the shelf were acquired. This paper presents the results of the processed high-resolution profiles together with sediment analyses. Our findings indicate: 1) There is little modern sediment accumulating on the shelf immediately off the Ayeyarwady River mouths. In contrast, a major mud wedge with a distal depocenter, up to 60 m in thickness, has been deposited seaward in the Gulf of Martaban, extending to ~130 m water depth into the Martaban Depression. Further, 2) There is no evidence showing that modern sediment has accumulated or is transported into the Martaban Canyon; 3) There is a mud drape/blanket wrapping around the narrow western Myanmar Shelf in the eastern Bay of Bengal. The thickness of the mud deposit is up to 20 m nearshore and gradually thins to the slope at −300 m water depth, and likely escapes into the deep Andaman Trench; 4) The estimated total amount of Holocene sediments deposited offshore is ~1290 × 109 tons. If we assume this has mainly accumulated since the middle Holocene highstand (~6000 yr BP) like other major deltas, the historical annual mean depositional flux on the shelf would be 215 Mt/yr, which is equivalent to ~35% of the modern Ayeyarwady-Thanlwin rivers derived sediments; 5) Unlike other large river systems in Asia, such as the Yangtze and Mekong, this study indicates a bi-directional transport and depositional pattern controlled by the local currents that are influenced by tides, and seasonally varying monsoons winds and waves. Organic carbon biomarkers and isotope compositions show a gradual changing pattern with the along-shelf transport from the river to the Gulf of Martaban in the east and to the Bay of Bengal in the west.
DA - 2020/5//
PY - 2020/5//
DO - 10.1016/j.margeo.2020.106137
VL - 423
SP -
SN - 1872-6151
KW - Ayeyarwady
KW - Andaman Sea
KW - Gulf of Martaban
KW - Sediment transport
KW - Subaqueous Delta
KW - Clinoform
KW - Bay of Bengal
ER -
TY - JOUR
TI - Mesoscale and submesoscale mechanisms behind asymmetric cooling and phytoplankton blooms induced by hurricanes: a comparison between an open ocean case and a continental shelf sea case (vol 68, pg 1443, 2018)
AU - McGee, Laura
AU - He, Ruoying
T2 - OCEAN DYNAMICS
AB - The original version of this article unfortunately contained a mistake. The following data attribution statement per our research sponsors requirement has been omitted.
DA - 2020/6//
PY - 2020/6//
DO - 10.1007/s10236-020-01371-7
VL - 70
IS - 6
SP - 843-843
SN - 1616-7228
UR - https://doi.org/10.1007/s10236-020-01371-7
ER -
TY - JOUR
TI - Evaluation of Regional Air Quality Models over Sydney, Australia: Part 2, Comparison of PM2.5 and Ozone
AU - Guerette, Elise-Andree
AU - Chang, Lisa Tzu-Chi
AU - Cope, Martin E.
AU - Duc, Hiep N.
AU - Emmerson, Kathryn M.
AU - Monk, Khalia
AU - Rayner, Peter J.
AU - Scorgie, Yvonne
AU - Silver, Jeremy D.
AU - Simmons, Jack
AU - Trieu, Toan
AU - Utembe, Steven R.
AU - Zhang, Yang
AU - Paton-Walsh, Clare
T2 - ATMOSPHERE
AB - Accurate air quality modelling is an essential tool, both for strategic assessment (regulation development for emission controls) and for short-term forecasting (enabling warnings to be issued to protect vulnerable members of society when the pollution levels are predicted to be high). Model intercomparison studies are a valuable support to this work, being useful for identifying any issues with air quality models, and benchmarking their performance against international standards, thereby increasing confidence in their predictions. This paper presents the results of a comparison study of six chemical transport models which have been used to simulate short-term hourly to 24 hourly concentrations of fine particulate matter less than and equal to 2.5 µm in diameter (PM2.5) and ozone (O3) for Sydney, Australia. Model performance was evaluated by comparison to air quality measurements made at 16 locations for O3 and 5 locations for PM2.5, during three time periods that coincided with major atmospheric composition measurement campaigns in the region. These major campaigns included daytime measurements of PM2.5 composition, and so model performance for particulate sulfate (SO42−), nitrate (NO3−), ammonium (NH4+) and elemental carbon (EC) was evaluated at one site per modelling period. Domain-wide performance of the models for hourly O3 was good, with models meeting benchmark criteria and reproducing the observed O3 production regime (based on the O3/NOx indicator) at 80% or more of the sites. Nevertheless, model performance was worse at high (and low) O3 percentiles. Domain-wide model performance for 24 h average PM2.5 was more variable, with a general tendency for the models to under-predict PM2.5 concentrations during the summer and over-predict PM2.5 concentrations in the autumn. The modelling intercomparison exercise has led to improvements in the implementation of these models for Sydney and has increased confidence in their skill at reproducing observed atmospheric composition.
DA - 2020/3//
PY - 2020/3//
DO - 10.3390/atmos11030233
VL - 11
IS - 3
SP -
SN - 2073-4433
KW - air quality modelling
KW - model evaluation
KW - PM2
KW - 5
KW - O-3
ER -
TY - JOUR
TI - A comparison of inner Solar System volcanism
AU - Byrne, Paul K.
T2 - NATURE ASTRONOMY
DA - 2020/4//
PY - 2020/4//
DO - 10.1038/s41550-019-0944-3
VL - 4
IS - 4
SP - 321-327
SN - 2397-3366
ER -
TY - JOUR
TI - The impact of alternative nutrient kinetics and computational grid size on model predicted primary production and hypoxic area in the northern Gulf of Mexico
AU - Pauer, James J.
AU - Melendez, Wilson
AU - Feist, Timothy J.
AU - Lehrter, John C.
AU - Rashleigh, Brenda
AU - Lowe, Lisa L.
AU - Greene, Richard M.
T2 - ENVIRONMENTAL MODELLING & SOFTWARE
AB - Model structure uncertainty is seldom calculated because of the difficulty and time required to perform such analyses. Here we explore how a coastal model using the Monod versus Droop formulations and a 6 km × 6 km versus 2 km × 2 km computational grid size predict primary production and hypoxic area in the Gulf of Mexico. Results from these models were compared to each other and to observations, and sensitivity analyses were performed. The different models fit the observations almost equally well. The 6k-model calculated higher rates of production and settling, and especially a larger hypoxic area, in comparison to the 2k-model. The Monod-based model calculated higher production, especially close to the river delta regions, but smaller summer hypoxic area, than the model using the Droop formulation. The Monod-based model was almost twice as sensitive to changes in nutrient loads in comparison to the Droop model, which can have management implications.
DA - 2020/4//
PY - 2020/4//
DO - 10.1016/j.envsoft.2020.104661
VL - 126
SP -
SN - 1873-6726
ER -
TY - JOUR
TI - Quaternary drainage network reorganization in the Colombian Eastern Cordillera plateau
AU - Struth, Lucia
AU - Giachetta, Emanuele
AU - Willett, Sean D.
AU - Owen, Lewis A.
AU - Teson, Eliseo
T2 - EARTH SURFACE PROCESSES AND LANDFORMS
AB - Abstract Dramatic drainage reorganization from initial longitudinal to transversal domains has occurred in the Eastern Cordillera of Colombia. We perform a regional analysis of drainage basin geometry and transformed river profiles based on the integral form of the slope‐area scaling, to investigate the dynamic state of drainage networks and to predict the degree of drainage reorganization in this region. We propose a new model of drainage rearrangement for the Eastern Cordillera, based on the analyses of knickpoint distribution, normalized river profiles, landforms characteristic of river capture, erosion rates and palaeodrainage data. We establish that the oldest longitudinal basin captured by the Magdalena River network was the Suárez Basin at ≈409 ka, inferring the timing of abandonment of a river terrace using in situ produced cosmogenic beryllium‐10 ( 10 Be) depth profiles and providing a first estimation of incision rate of 0.07 mm/yr. We integrate published geochronologic data and interpret the last capture of the Sabana de Bogotá, providing a minimum age of the basin opening to the Magdalena drainage at ≈38 ka. Our results suggest that the Magdalena basin Increased its drainage area by integrating the closed basins from the western flank of the Eastern Cordillera. Our study also suggests that the Magdalena basin is an aggressor compared to the basins located in the eastern flank of the orogen and provides a framework for examining drainage reorganization within the Eastern Cordillera and in similar orogenic settings. The results improve our understanding of headward integration of closed basins across orogenic plateaux. © 2020 John Wiley & Sons, Ltd.
DA - 2020/6/30/
PY - 2020/6/30/
DO - 10.1002/esp.4846
VL - 45
IS - 8
SP - 1789-1804
SN - 1096-9837
KW - drainage evolution
KW - fluvial capture
KW - cosmogenic nuclides
KW - chi analysis
KW - Eastern Cordillera of Colombia
ER -
TY - JOUR
TI - Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010-Part 1: Model evaluation and air mass characterization for stratosphere-troposphere transport
AU - Itahashi, Syuichi
AU - Mathur, Rohit
AU - Hogrefe, Christian
AU - Zhang, Yang
T2 - ATMOSPHERIC CHEMISTRY AND PHYSICS
AB - Abstract. Stratospheric intrusion and trans-Pacific transport have been recognized as a potential source of tropospheric ozone over the US. The state-of-the-science Community Multiscale Air Quality (CMAQ) modeling system has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ). In this study, H-CMAQ is applied to study the stratospheric intrusion and trans-Pacific transport during April 2010. The results will be presented in two companion papers. In this Part 1 paper, model evaluation for tropospheric ozone (O3) is presented. Observations at the surface, by ozonesondes and airplane, and by satellite across the Northern Hemisphere are used to evaluate the model performance for O3. H-CMAQ is able to capture surface and boundary layer (defined as surface to 750 hPa) O3 with a normalized mean bias (NMB) of −10 %; however, a systematic underestimation with an NMB up to −30 % is found in the free troposphere (defined as 750–250 hPa). In addition, a new air mass characterization method is developed to distinguish influences of stratosphere–troposphere transport (STT) from the effects of photochemistry on O3 levels. This method is developed based on the ratio of O3 and an inert tracer indicating stratospheric O3 to examine the importance of photochemistry, and sequential intrusion from upper layer. During April 2010, on a monthly average basis, the relationship between surface O3 mixing ratios and estimated stratospheric air masses in the troposphere show a slight negative slope, indicating that high surface O3 values are primarily affected by other factors (i.e., emissions), whereas this relationship shows a slight positive slope at elevated sites, indicating that STT has a possible impact at elevated sites. STT shows large day-to-day variations, and STT impacts can either originate from the same air mass over the entire US with an eastward movement found during early April, or stem from different air masses at different locations indicated during late April. Based on this newly established air mass characterization technique, this study can contribute to understanding the role of STT and also the implied importance of emissions leading to high surface O3. Further research focused on emissions is discussed in a subsequent paper (Part 2).
DA - 2020/3/23/
PY - 2020/3/23/
DO - 10.5194/acp-20-3373-2020
VL - 20
IS - 6
SP - 3373-3396
SN - 1680-7324
ER -
TY - JOUR
TI - Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010-Part 2: Examination of emission impacts based on the higher-order decoupled direct method
AU - Itahashi, Syuichi
AU - Mathur, Rohit
AU - Hogrefe, Christian
AU - Napelenok, Sergey L.
AU - Zhang, Yang
T2 - ATMOSPHERIC CHEMISTRY AND PHYSICS
AB - Abstract. The state-of-the-science Community Multiscale Air Quality (CMAQ) modeling system, which has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ), is applied to study the trans-Pacific transport, a phenomenon recognized as a potential source of air pollution in the US, during April 2010. The results of this analysis are presented in two parts. In the previous paper (Part 1), model evaluation for tropospheric ozone (O3) was presented and an air mass characterization method was developed. Results from applying this newly established method pointed to the importance of emissions as the factor to enhance the surface O3 mixing ratio over the US. In this subsequent paper (Part 2), emission impacts are examined based on mathematically rigorous sensitivity analysis using the higher-order decoupled direct method (HDDM) implemented in H-CMAQ. The HDDM sensitivity coefficients indicate the presence of a NOx-sensitive regime during April 2010 over most of the Northern Hemisphere. By defining emission source regions over the US and east Asia, impacts from these emission sources are examined. At the surface, during April 2010, the emission impacts of the US and east Asia are comparable over the western US with a magnitude of about 3 ppbv impacts on monthly mean O3 all-hour basis, whereas the impact of domestic emissions dominates over the eastern US with a magnitude of about 10 ppbv impacts on monthly mean O3. The positive correlation (r=0.63) between surface O3 mixing ratios and domestic emission impacts is confirmed. In contrast, the relationship between surface O3 mixing ratios and emission impacts from east Asia exhibits a flat slope when considering the entire US. However, this relationship has strong regional differences between the western and eastern US; the western region exhibits a positive correlation (r=0.36–0.38), whereas the latter exhibits a flat slope (r < 0.1). Based on the comprehensive evaluation of H-CMAQ, we extend the sensitivity analysis for O3 aloft. The results reveal the significant impacts of emissions from east Asia on the free troposphere (defined as 750 to 250 hPa) over the US (impacts of more than 5 ppbv) and the dominance of stratospheric air mass on upper model layer (defined as 250 to 50 hPa) over the US (impacts greater than 10 ppbv). Finally, we estimate changes of trans-Pacific transport by taking into account recent emission trends from 2010 to 2015 assuming the same meteorological condition. The analysis suggests that the impact of recent emission changes on changes in the contribution of trans-Pacific transport to US O3 levels was insignificant at the surface level and was small (less than 1 ppbv) over the free troposphere.
DA - 2020/3/23/
PY - 2020/3/23/
DO - 10.5194/acp-20-3397-2020
VL - 20
IS - 6
SP - 3397-3413
SN - 1680-7324
ER -
TY - JOUR
TI - Circulation Dynamics and Seasonal Variability for the Charlotte Harbor Estuary, Southwest Florida Coast
AU - Dye, Bass
AU - Jose, Felix
AU - Allahdadi, Mohammad Nabi
T2 - JOURNAL OF COASTAL RESEARCH
AB - Dye, B.; Jose, F., and Allahdadi, M.N., 2020. Circulation dynamics and seasonal variability for the Charlotte Harbor Estuary, Southwest Florida coast. Journal of Coastal Research, 36(2), 276–288. Coconut Creek (Florida), ISSN 0749-0208.A hydrodynamic model was developed and validated for the Charlotte Harbor estuarine system, located in SW Florida, to elucidate freshwater fluxes within the system's various inlets during diverse hydrologic conditions. Fresh water entering the system not only varies seasonally but also, because of regulatory fresh water, releases controlling water levels within an upstream lake. The unnatural freshwater releases have been found to negatively affect the system's ecology, in particular within the Caloosahatchee River portion of the system. Neither the flood nor ebb phase exhibits uniform dominance in flushing the system's four major passes. Boca Grande Pass and Big Carlos Pass were mostly ebb dominant, whereas San Carlos Bay was largely flood dominant; neither phase dominated at Captiva Pass. The similarities and/or contradictions of these results in comparison to former field and modeling results are mainly attributed to the differences between the freshwater sources and environmental forces corresponding to each study that forces a different mass-balance condition over the estuary-bay system and, thereby, at each individual inlet. A Lagrangian particle tracking study revealed particles released within the Peace River during different hydrological conditions were comparably transported regardless of freshwater inputs and predominate wind direction. In contrast, particles released within the Caloosahatchee River were flushed into the Gulf of Mexico within 10 days during a usually wet El Niño, dry (November–April) season period whereas during the summer wet (May–October) season released particles remained in the estuary for a longer period (13 days), ultimately resulting in their further transport into Pine Island Sound and Matlacha Pass. The results also demonstrate the effect of freshwater river inputs and wind on the travel time of the neutrally buoyant particles within the estuarine system. The hydrodynamic and coupled particle tracking model serve as the first step in a forthcoming larval transport modeling study.
DA - 2020/3//
PY - 2020/3//
DO - 10.2112/JCOASTRES-D-19-00071.1
VL - 36
IS - 2
SP - 276-288
SN - 1551-5036
KW - Hydrodynamic model
KW - Caloosahatchee River
KW - shallow estuary
KW - MIKE model
KW - tidal inlets
KW - particle tracking
ER -
TY - JOUR
TI - A morphological evaluation of crater degradation on Mercury: Revisiting crater classification with MESSENGER data
AU - Kinczyk, Mallory J.
AU - Prockter, Louise M.
AU - Byrne, Paul K.
AU - Susorney, Hannah C. M.
AU - Chapman, Clark R.
T2 - ICARUS
AB - Observations of impact crater morphology can be used to gain insight into the geological history and evolution of a planet's surface. Image data from the Mariner 10 mission revealed the diversity of impact crater morphologies and degradational states on Mercury, leading to early studies that sought to establish a stratigraphic column for the planet, despite only acquiring image data for ~45% of the surface. In 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered orbit around Mercury, returning a high-resolution global image dataset that enables a robust analysis of crater morphology and degradation to be completed for the entirety of Mercury's surface. In this study, we conducted a visual classification of crater degradation according to initial crater morphology, and assigned a degradation state to all craters on Mercury ≥40 km in diameter. In our scheme, Class 1 craters are those that are heavily degraded, and Class 5 craters are very fresh with bright ray systems. We discuss the processes involved in crater degradation and erasure, and the challenges associated with applying crater degradation to derive the timing of geological events. We found that, based on the global spatial density of craters in each class, there appears to be a dearth of Class 1 craters within the intercrater plains, likely due to several ancient basin-sized impacts effectively obliterating a considerable portion of craters ≥40 km in diameter in this region. The crater degradation database we present here will serve as a useful tool for future analyses of Mercury's geological evolution.
DA - 2020/5/1/
PY - 2020/5/1/
DO - 10.1016/j.icarus.2020.113637
VL - 341
SP -
SN - 1090-2643
KW - Mercury (planet)
KW - Impact craters
KW - Degradation
KW - Crater morphology
ER -
TY - JOUR
TI - African Easterly Wave Dynamics in Convection-Permitting Simulations: Rotational Stratiform Instability as a Conceptual Model
AU - Russell, James O. H.
AU - Aiyyer, Anantha
AU - Dylan White, J.
T2 - JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
AB - Abstract We examine the upscale effect of moist convection on African easterly waves (AEWs) by limiting condensational heating and initial ambient moisture in convection‐permitting simulations. Moist convection is fundamental in maintaining and destabilizing AEWs. The contribution from barotropic‐baroclinic instability, albeit important, is relatively smaller. Mesoscale convective systems (MCSs) are initiated downstream of the AEW troughs and are associated with extensive trailing stratiform cloud regions. Using a potential vorticity (PV) budget, we show that the attendant diabatic heating profile reinforces the AEW. A model for destabilization is proposed that relies on the phasing of stratiform heating and the PV anomaly of the AEW. It qualitatively resembles stratiform instability and stretched building blocks hypotheses introduced in previous studies. The generation of PV by deep moist convection in the vicinity of the trough counters the shearing effect of the background flow. This helps maintain an upright PV column, which is conducive for formation of tropical cyclones. AEW propagation is dominated by advective processes and intermittently modified by moist convection when large MCSs move ahead of the AEW.
DA - 2020/1//
PY - 2020/1//
DO - 10.1029/2019MS001706
VL - 12
IS - 1
SP -
SN - 1942-2466
KW - African easterly waves
KW - tropical convection
KW - tropical waves
KW - potential vorticity
KW - tropical meteorology
KW - conceptual model
ER -
TY - JOUR
TI - Characterization of the Global Sources of Atmospheric Ammonia from Agricultural Soils
AU - Aneja, Viney P.
AU - Schlesinger, William H.
AU - Li, Qi
AU - Nahas, Alberth
AU - Battye, William H.
T2 - JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
AB - Abstract Global ammonia (NH 3 ) emissions to the atmosphere are projected to increase in the coming years with the increased use of synthetic nitrogen fertilizers and cultivation of nitrogen‐fixing crops. A statistical model (NH 3 _STAT) is developed for characterizing atmospheric NH 3 emissions from agricultural soils and compared to the performance of other global and regional NH 3 models (e.g., Emission Database for Global Atmospheric Research, Magnitude and Seasonality of Agricultural Emissions, MIX, and U.S. Environmental Protection Agency). The statistical model was developed from a multiple linear regression between NH 3 emission and the physicochemical variables. The model was evaluated for 2012 NH 3 emissions. The results indicate that, in comparison to other data sets, the model provides a lower global NH 3 estimate by 58%, (NH 3 _STAT: 13.9 Tg N yr −1 ; Emission Database for Global Atmospheric Research: 33.0 Tg N yr −1 ). We also performed a region‐based analysis (United States, India, and China) using the NH 3 _STAT model. For the United States, our model produces an estimate that is a ~1.4 times higher in comparison to the Environmental Protection Agency. Meanwhile, the NH 3 _STAT estimate for India shows NH 3 emissions between 0.8 and 1.4 times lower when compared to other data sets. A lower estimate is also seen for China, where the model estimates NH 3 emissions 0.4 to 5 times lower than other data sets. The difference in the global estimates is attributed to the lower estimates in major agricultural countries like China and India. The statistical model captures the spatial distribution of global NH 3 emissions by utilizing a simplified approach compared to other readily available data sets. Moreover, the NH 3 _STAT model provides an opportunity to predict future NH 3 emissions in a changing world.
DA - 2020/2/16/
PY - 2020/2/16/
DO - 10.1029/2019JD031684
VL - 125
IS - 3
SP -
SN - 2169-8996
UR - https://doi.org/10.1029/2019JD031684
ER -
TY - JOUR
TI - The present-day atmospheric dust deposition process in the South China Sea
AU - Du, Shuhuan
AU - Xiang, Rong
AU - Liu, Jianguo
AU - Liu, J. Paul
AU - Islam, G. M. Ariful
AU - Chen, Muhong
T2 - ATMOSPHERIC ENVIRONMENT
AB - Modern dust plays essential roles in marine and climate processes, which bring continental material to the ocean and sensitivity in marine ecosystems. However, the atmospheric dust deposition process has rarely been studied in the South China Sea (SCS). Here, we present 51 atmospheric dust samples, collected along the SCS, to investigate the grain size distribution, depositional flux, and features revealed by scanning electron microscopy, combined with 5-day back trajectories to indicate the present-day dust deposition process for the first time. The grain size distribution and depositional flux of aerosol samples illustrate the seasonal trend: coarser particle and higher flux mass in winter than summer. The average grain size is 5.75 μm during winter and 3.62 μm from summer, and the depositional flux in the winter is 1.4 times than that in summer, both are related to the transport pathway and power of the East Asian monsoon. Modeled 5-day back trajectories of dust samples suggest a southwesterly transport pathway in summer and the Southeast Asian monsoon as a possible source of the dust loading, while the northeast winds drove the aeolian dust transport during the winter monsoon from the Asian continent. Meanwhile, westerly circulation conveys the fine particles (~0.63 μm) as the stable terrigenous component into the SCS, deposited through the entire dust deposition process from the atmosphere and water to the surface sediment. Furthermore, the surface of quartz particles from atmospheric dust shows the unique structure in the aeolian environment as a reference to distinguish the different continental components in the sediments. This study provides new insights into the present-day dust deposition process in the SCS, significantly extending the current understanding of the relationship between atmospheric dust and the marginal sea.
DA - 2020/2/15/
PY - 2020/2/15/
DO - 10.1016/j.atmosenv.2020.117261
VL - 223
SP -
SN - 1873-2844
KW - Atmospheric dust
KW - Grain size
KW - Transport process
KW - SEM
KW - South China sea
ER -
TY - JOUR
TI - Do asymmetries in ENSO predictability arise from different recharged states?
AU - Larson, Sarah M.
AU - Pegion, Kathy
T2 - CLIMATE DYNAMICS
DA - 2020/2//
PY - 2020/2//
DO - 10.1007/s00382-019-05069-5
VL - 54
IS - 3-4
SP - 1507-1522
SN - 1432-0894
ER -
TY - JOUR
TI - The Potential Vorticity Structure and Dynamics of African Easterly Waves
AU - Russell, James O. H.
AU - Aiyyer, Anantha
T2 - JOURNAL OF THE ATMOSPHERIC SCIENCES
AB - Abstract The dynamics of African easterly waves (AEWs) are investigated from the perspective of potential vorticity (PV) using data from global reanalysis projects. To a leading order, AEW evolution is governed by four processes: advection of the wave-scale PV by background flow, advection of background PV by the AEW, diabatic forcing due to wave-scale moist convection, and coupling between the wave and background diabatic forcing. Moist convection contributes significantly to the growth of AEWs in the midtroposphere, and to both growth and propagation of AEWs near the surface. The former is associated with stratiform clouds while the latter with deep convection. Moist convection helps maintain a more upright AEW PV column against the background shear, which makes the wave structure conducive for tropical cyclogenesis. It is also argued that—contrary to the hypothesis in some prior studies—the canonical diabatic Rossby wave model is likely not applicable to AEWs.
DA - 2020/3//
PY - 2020/3//
DO - 10.1175/JAS-D-19-0019.1
VL - 77
IS - 3
SP - 871-890
SN - 1520-0469
KW - Deep convection
KW - Dynamics
KW - Potential vorticity
KW - Synoptic climatology
KW - Waves
KW - atmospheric
ER -
TY - JOUR
TI - Dityrosine formation via reactive oxygen consumption yields increasingly recalcitrant humic‐like fluorescent organic matter in the ocean
AU - Paerl, Ryan W.
AU - Claudio, Iliana M.
AU - Shields, Michael R.
AU - Bianchi, Thomas S.
AU - Osburn, Christopher L.
T2 - Limnology and Oceanography Letters
AB - Abstract Marine dissolved organic matter (DOM) is a massive elemental pool on Earth and is thought to consist of a chemically complex mixture of molecules. Part of marine DOM is fluorescent (FDOM) and includes humic‐like compounds. The chemical composition of, and biochemical pathways that yield, autochthonous humic‐like FDOM in the ocean is largely unknown. Inspired by medical and biochemical research detailing the formation of colored and fluorescent dityrosine via peroxidase mediated reactions, we used fluorometry and spectroscopy and found dityrosine exhibits humic‐like fluorescence similar to that of marine FDOM. Investigating its recalcitrance, we conducted short‐term nutrient‐addition and light exposure experiments with dityrosine and found it is resistant to respiration or assimilation by marine microbial communities, yet readily photodegraded. The formation and characteristics of dityrosine newly points to polymerization via reactive oxygen quenching, under aphotic and putatively photic conditions, as an explanation for autochthonous, humic‐like, (semi‐)recalcitrant DOM in the ocean.
DA - 2020/10//
PY - 2020/10//
DO - 10.1002/lol2.10154
UR - https://doi.org/10.1002/lol2.10154
ER -
TY - JOUR
TI - Landslide development within 3 years after the 2015 M-w 7.8 Gorkha earthquake, Nepal
AU - Tian, Yingying
AU - Owen, Lewis A.
AU - Xu, Chong
AU - Ma, Siyuan
AU - Li, Kang
AU - Xu, Xiwei
AU - Figueiredo, Paula Marques
AU - Kang, Wenjun
AU - Guo, Peng
AU - Wang, Siyu
AU - Liang, Xiaohua
AU - Maharjan, Sudan Bikash
T2 - LANDSLIDES
DA - 2020/5//
PY - 2020/5//
DO - 10.1007/s10346-020-01366-x
VL - 17
IS - 5
SP - 1251-1267
SN - 1612-5118
UR - http://dx.doi.org/10.1007/s10346-020-01366-x
KW - 2015 Gorkha earthquake
KW - Nepal
KW - Himalaya
KW - Landsliding
KW - Ground-based investigation
KW - UAV photography
KW - Remote sensing
ER -
TY - JOUR
TI - Assessing the distribution of labile organic carbon from diverse depositional environments on the West Antarctic Peninsula shelf
AU - Taylor, Richard S.
AU - DeMaster, David J.
AU - Burdige, David J.
T2 - DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
AB - The seabed distributions of labile organic carbon (LOC), i.e., recently produced organic matter from marine plankton, were studied in a variety of depositional environments on the West Antarctic Peninsula continental shelf using the naturally occurring radioisotopes, 14C, 210Pb and 234Th. The effects of bioturbation on the LOC pool were assessed on short-term (seasonal, using 234Thxs within the upper, 2–5 cm) and long-term (decadal, using 210Pbxs from 3-22 cm) timescales to generate LOC degradation coefficients (k) and mean residence times (MRT or τ-LOC) as a function of depth within the sediment column. Based on 234Th distributions, mixing coefficients (Db) ranged from 2 cm2/y to 36 cm2/y, which resulted in LOC MRT values that varied from 0.8y to 9.8y. Based on 210Pb distributions, Db values at depth ranged from 0.2 cm2/y to 1.8 cm2/y, resulting in MRT values that varied from 32y to 4900y. Along the West Antarctic Peninsula, seabed inventories of LOC varied between 17-70 mg/cm2. Bulk LOC becomes less reactive and ages with time during resuspension and transport across the shelf and as LOC is transported deeper within the sediment column by infaunal feeding activities.
DA - 2020/2//
PY - 2020/2//
DO - 10.1016/j.dsr.2019.103166
VL - 156
SP -
SN - 1879-0119
KW - West Antarctic Peninsula
KW - Labile organic carbon
KW - Radiocarbon
KW - Bioturbation
KW - Diagenesis
KW - Marine sedimentary processes
ER -
TY - JOUR
TI - On the limit to the accuracy of regional-scale air quality models
AU - Rao, S. Trivikrama
AU - Luo, Huiying
AU - Astitha, Marina
AU - Hogrefe, Christian
AU - Garcia, Valerie
AU - Mathur, Rohit
T2 - ATMOSPHERIC CHEMISTRY AND PHYSICS
AB - Abstract. Regional-scale air pollution models are routinely being used worldwide for research, forecasting air quality, and regulatory purposes. It is well recognized that there are both reducible (systematic) and irreducible (unsystematic) errors in the meteorology–atmospheric-chemistry modeling systems. The inherent (random) uncertainty stems from our inability to properly characterize stochastic variations in atmospheric dynamics and chemistry and from the incommensurability associated with comparisons of the volume-averaged model estimates with point measurements. Because stochastic variations are not being explicitly simulated in the current generation of regional-scale meteorology–air quality models, one should expect to find differences between the model estimates and corresponding observations. This paper presents an observation-based methodology to determine the expected errors from current-generation regional air quality models even when the model design, physics, chemistry, and numerical analysis, as well as its input data, were “perfect”. To this end, the short-term synoptic-scale fluctuations embedded in the daily maximum 8 h ozone time series are separated from the longer-term forcing using a simple recursive moving average filter. The inherent uncertainty attributable to the stochastic nature of the atmosphere is determined based on 30+ years of historical ozone time series data measured at various monitoring sites in the contiguous United States (CONUS). The results reveal that the expected root mean square error (RMSE) at the median and 95th percentile is about 2 and 5 ppb, respectively, even for perfect air quality models driven with perfect input data. Quantitative estimation of the limit to the model's accuracy will help in objectively assessing the current state of the science in regional air pollution models, measuring progress in their evolution, and providing meaningful and firm targets for improvements in their accuracy relative to ambient measurements.
DA - 2020/2/10/
PY - 2020/2/10/
DO - 10.5194/acp-20-1627-2020
VL - 20
IS - 3
SP - 1627-1639
SN - 1680-7324
ER -
TY - JOUR
TI - Quantifying national and regional cyanobacterial occurrence in US lakes using satellite remote sensing
AU - Coffer, Megan M.
AU - Schaeffer, Blake A.
AU - Darling, John A.
AU - Urquhart, Erin A.
AU - Salls, Wilson B.
T2 - ECOLOGICAL INDICATORS
AB - Cyanobacterial harmful algal blooms are the most common form of harmful algal blooms in freshwater systems throughout the world. However, in situ sampling of cyanobacteria in inland lakes is limited both spatially and temporally. Satellite data has proven to be an effective tool to monitor cyanobacteria in freshwater lakes across the United States. This study uses data from the European Space Agency Envisat MEdium Resolution Imaging Spectrometer and the Sentinel-3 Ocean and Land Color Instrument to provide a national overview of the percentage of lakes experiencing a cyanobacterial bloom on a weekly basis for 2008–2011, 2017, and 2018. A total of 2321 lakes across the contiguous United States were included in the analysis. We examined four different thresholds to define when a waterbody is classified as experiencing a bloom. Across these four thresholds, we explored variability in bloom percentage with changes in seasonality and lake size. As a validation of algorithm performance, we analyzed the agreement between satellite observations and previously established ecological patterns, although data availability in the wintertime limited these comparisons on a year-round basis. Changes in cyanobacterial bloom percentage at the national scale followed the well-known temporal pattern of freshwater blooms. The percentage of lakes experiencing a bloom increased throughout the year, reached a maximum in fall, and decreased through the winter. Wintertime data, particularly in northern regions, were consistently limited due to snow and ice cover. With the exception of the Southeast and South, regional patterns mimicked patterns found at the national scale. The Southeast and South exhibited an unexpected pattern as cyanobacterial bloom percentage reached a maximum in the winter rather than the summer. Lake Jesup in Florida was used as a case study to validate this observed pattern against field observations of chlorophyll a. Results from this research establish a baseline of annual occurrence of cyanobacterial blooms in inland lakes across the United States. In addition, methods presented in this study can be tailored to fit the specific requirements of an individual system or region.
DA - 2020/4//
PY - 2020/4//
DO - 10.1016/j.ecolind.2019.105976
VL - 111
SP -
SN - 1872-7034
KW - Remote sensing
KW - Harmful algal blooms
KW - Cyanobacteria
KW - Water quality
KW - Inland waters
ER -
TY - JOUR
TI - Wealth in people and the value of historic Oberlin Cemetery, Raleigh, North Carolina
AU - McGill, Dru
AU - Millhauser, John K.
AU - McGill, Alicia
AU - Melomo, Vincent
AU - Bohnenstiehl, Del
AU - Wall, John
T2 - ECONOMIC ANTHROPOLOGY
AB - In its origins as a concept, wealth in people depended on the circulation and accumulation of rights and obligations among and over the living. But if a person is a source of wealth, what happens when the person dies? Would the person be excised from the relationships upon which wealth in people depends, or might his or her wealth remain accessible to the living? To address this question, we present the case of Oberlin Cemetery in Raleigh, North Carolina. The cemetery was the core of Oberlin Village, a freedperson's African American community founded in the mid‐nineteenth century. Today, development threatens historic resources surrounding the cemetery, but a community organization founded by descendants and neighbors has emerged to preserve and promote their heritage. We are a group of anthropologists, geologists, and historians who live and work near Oberlin Village and who collaborate to help this organization achieve its goals. Here we report how our efforts to document the cemetery's history have bolstered their advocacy and validated their claims to wealth in the people buried there. Thus we show how wealth in people extends to the dead when graves and the people within them are potent sources of value for the living.
DA - 2020/6//
PY - 2020/6//
DO - 10.1002/sea2.12173
VL - 7
IS - 2
SP - 176-189
SN - 2330-4847
KW - Wealth in People
KW - Cemeteries
KW - Community-Based Research
KW - African American Heritage
ER -
TY - JOUR
TI - Pulsed terrestrial organic carbon persists in an estuarine environment after major storm events
AU - Asmala, Eero
AU - Osburn, Christopher
AU - Paerl, Ryan
AU - Paerl, Hans
AB - <p>The transport of dissolved organic carbon from land to ocean is a large and dynamic component of the global carbon cycle. Export of dissolved organic carbon from watersheds is largely controlled by hydrology, and is exacerbated by increasing major rainfall and storm events, causing pulses of terrestrial dissolved organic carbon (DOC) to be shunted through rivers downstream to estuaries. Despite this increasing trend, the fate of the pulsed terrestrial DOC in estuaries remains uncertain. Here we present DOC data from 1999 to 2017 in Neuse River Estuary (NC, USA) and analyze the effect of six tropical cyclones (TC) during that period on the quantity and fate of DOC in the estuary. We find that that TCs promote a considerable increase in DOC concentration near the river mouth at the entrance to the estuary, on average an increase of 200 &#181;mol l<sup>-1</sup> due to storms was observed. TC-induced increases in DOC are apparent throughout the estuary, and the duration of these elevated DOC concentrations ranges from one month at the river mouth to over six months in lower estuary. Our results suggest that despite the fast mineralization rates, the terrestrial DOC is processed only to a minor extent relative to the pulsed amount entering the estuary. We conclude that the vast quantity of organic carbon delivered to estuaries by TCs transform estuaries from active biogeochemical processing &#8220;reactors&#8221; of organic carbon to appear more like passive shunts due to the sheer amount of pulsed material rapidly flushed through the estuary.</p>
DA - 2020/3/23/
PY - 2020/3/23/
DO - 10.5194/egusphere-egu2020-8587
VL - 3
UR - https://doi.org/10.5194/egusphere-egu2020-8587
ER -
TY - JOUR
TI - Use of Geospatial, Hydrologic, and Geochemical Modeling to Determine the Influence of Wetland-Derived Organic Matter in Coastal Waters in Response to Extreme Weather Events
AU - Rudolph, Jacob C.
AU - Arendt, Carli A.
AU - Hounshell, Alexandria G.
AU - Paerl, Hans W.
AU - Osburn, Christopher L.
T2 - FRONTIERS IN MARINE SCIENCE
AB - Flooding from extreme weather events (EWE), such as hurricanes, exports large amounts of dissolved organic matter (DOM) to both estuaries and coastal waters globally. Hydrologic connectivity of wetlands to adjacent river channels during flood events is potentially a major control on the DOM exported to coastal waters after EWEs. In this study, a geographic information system based flood model was used to: 1) determine the volume of flooded wetlands in a river corridor following Hurricane Matthew in 2016; 2) compute the resulting volume fluxes of DOM to the Neuse River Estuary-Pamlico Sound (NRE-PS), in eastern North Carolina and 3) use the flood model to quantify the wetland contribution to DOM export. The flood model-derived contributions were validated with a Bayesian Monte Carlo mixing model combining measurements of DOM quality: specific UV Absorbance at 254 nm (SUVA254), spectral slope ratio (SR), and stable isotope ratios of dissolved organic carbon (13C-DOC). Results indicated that 1) hydrologic connectivity of the freshwater riparian wetlands caused the wetlands to become the primary source of organic matter (OM) that was exported into the NRE-PS after Matthew and 2) this source lingered in these coastal waters in the months after the storm. Thus, in consideration of the pulse-shunt concept, EWE such as Hurricane Matthew cause pulses of DOM from wetlands, which were the primary source of the OM shunted from the terrestrial environment to the estuary and sound. Wetlands constituted ca. 48% of the annual loading of DOC into the NRE and 16% of DOC loading into the PS. Results were consistent with prior studies in this system, and other coastal ecosystems, that attributed a high reactivity of DOM as the underlying reason for large CO2 releases following EWE. Adapting pulse-shunt concept to estuaries requires the addition of a “processing” step to account for the DOM to CO2 dynamics, thus a new pulse-shunt process is proposed to incorporate coastal waters. Our results suggest that with increasing frequency and intensity of EWE, strengthening of the lateral transfer of DOM from land to ocean will occur and has the potential to greatly impact coastal carbon cycling.
DA - 2020/2/7/
PY - 2020/2/7/
DO - 10.3389/fmars.2020.00018
VL - 7
SP -
SN - 2296-7745
KW - hydrologic connectivity
KW - dissolved organic matter
KW - extreme weather events
KW - stable carbon isotopes
KW - wetlands
ER -
TY - JOUR
TI - Website Usability Differences between Males and Females: An Eye-Tracking Evaluation of a Climate Decision Support System
AU - Maudlin, Lindsay C.
AU - McNeal, Karen S.
AU - Dinon-Aldridge, Heather
AU - Davis, Corey
AU - Boyles, Ryan
AU - Atkins, Rachel M.
T2 - WEATHER CLIMATE AND SOCIETY
AB - ABSTRACT Decision support systems—collections of related information located in a central place to be used for decision-making—can be used as platforms from which climate information can be shared with decision-makers. Unfortunately, these tools are not often evaluated, meaning developers do not know how useful or usable their products are. In this study, a web-based climate decision support system (DSS) for foresters in the southeastern United States was evaluated by using eye-tracking technology. The initial study design was exploratory and focused on assessing usability concerns within the website. Results showed differences between male and female forestry experts in their eye-tracking behavior and in their success with completing tasks and answering questions related to the climate information presented in the DSS. A follow-up study, using undergraduate students from a large university in the southeastern United States, aimed to determine whether similar gender differences existed and could be detected and, if so, whether the cause(s) could be determined. The second evaluation, similar to the first, showed that males and females focused their attention on different aspects of the website; males focused more on the maps depicting climate information while females focused more on other aspects of the website (e.g., text, search bars, and color bars). DSS developers should consider the possibility of gender differences when designing a web-based DSS and include website features that draw user attention to important DSS elements to effectively support various populations of users.
DA - 2020/1//
PY - 2020/1//
DO - 10.1175/WCAS-D-18-0127.1
VL - 12
IS - 1
SP - 183-192
SN - 1948-8335
KW - Communications
KW - decision making
ER -
TY - JOUR
TI - Modeling restorative potential of urban environments by coupling viewscape analysis of lidar data with experiments in immersive virtual environments
AU - Tabrizian, Payam
AU - Baran, Perver K.
AU - Van Berkel, Derek
AU - Mitasova, Helena
AU - Meentemeyer, Ross
T2 - LANDSCAPE AND URBAN PLANNING
AB - • We propose an approach for modeling experiential qualities of urban landscape. • We use lidar data to generate detailed model of landscape structure and patterns. • We combine GIS analysis of viewscapes with survey of immersive virtual environment. • We identify spatial metrics that predict urban landscape’s restorative potential (RP). • We develop a predictive map of RP that can support decision-making and urban design.
DA - 2020/3//
PY - 2020/3//
DO - 10.1016/j.landurbplan.2019.103704
VL - 195
SP -
SN - 1872-6062
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076054188&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Climate‐Driven Changes in Dissolved Organic Carbon and Water Clarity in Arctic Lakes of West Greenland
AU - Fowler, Rachel A.
AU - Osburn, Christopher L.
AU - Saros, Jasmine E.
T2 - Journal of Geophysical Research: Biogeosciences
AB - Abstract To assess climate‐mediated terrestrial‐aquatic linkages in Arctic lakes and potential impacts on light attenuation and carbon cycling, we evaluated lake responses to climate drivers in two areas of west Greenland with differing climate patterns. We selected four lakes in a warmer, drier area to compare with four lakes from a cooler, wetter area proximal to the Greenland Ice Sheet. In June from 2013–2018, we measured epilimnetic water temperature, 1% depth of photosynthetically active radiation (PAR), dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA 254 ), DOC‐normalized absorbance at 380 nm ( a * 380 ), and chlorophyll a . Interannual coherence of 1% PAR and DOC was particularly high for lakes within the warmer, drier area. This coherence suggests forcing of Arctic lake features by a large‐scale driver, likely climate. Redundancy analysis showed that monthly average precipitation, winter North Atlantic Oscillation (NAO) index (NAO W ), spring average air temperature, and spring average precipitation influenced the lake variables ( p = 0.003, adj. R 2 = 0.58). In particular, monthly average precipitation contributed to increases in soil‐derived DOC quality metrics and chlorophyll a and decreased 1% PAR. Interannual changes in lake responses to climate drivers were more apparent in the warmer, drier area than the cooler, wetter area. The interannual lake responses within and between areas, associated with climate trends, suggest that with ongoing rapid climate change in the Arctic, there could be widespread impacts on key lake responses important for light attenuation and carbon cycling.
DA - 2020/2//
PY - 2020/2//
DO - 10.1029/2019JG005170
UR - https://doi.org/10.1029/2019JG005170
KW - Arctic lakes
KW - Carbon cycling
KW - CDOM
KW - light attenuation
KW - Climate change
KW - Temporal coherence
ER -
TY - JOUR
TI - Open Geospatial Software and Data: A Review of the Current State and A Perspective into the Future
AU - Coetzee, Serena
AU - Ivánová, Ivana
AU - Mitasova, Helena
AU - Brovelli, Maria
T2 - ISPRS International Journal of Geo-Information
AB - All over the world, organizations are increasingly considering the adoption of open source software and open data. In the geospatial domain, this is no different, and the last few decades have seen significant advances in this regard. We review the current state of open source geospatial software, focusing on the Open Source Geospatial Foundation (OSGeo) software ecosystem and its communities, as well as three kinds of open geospatial data (collaboratively contributed, authoritative and scientific). The current state confirms that openness has changed the way in which geospatial data are collected, processed, analyzed, and visualized. A perspective on future developments, informed by responses from professionals in key organizations in the global geospatial community, suggests that open source geospatial software and open geospatial data are likely to have an even more profound impact in the future.
DA - 2020/2/1/
PY - 2020/2/1/
DO - 10.3390/ijgi9020090
VL - 9
IS - 2
SP - 90
UR - https://doi.org/10.3390/ijgi9020090
KW - geospatial data
KW - geospatial software
KW - open data
KW - open source software
ER -
TY - JOUR
TI - Uncertainty Estimates for Sea Surface Temperature and Land Surface Air Temperature in NOAAGlobalTemp Version 5
AU - Huang, Boyin
AU - Menne, Matthew J.
AU - Boyer, Tim
AU - Freeman, Eric
AU - Gleason, Byron E.
AU - Lawrimore, Jay H.
AU - Liu, Chunying
AU - Rennie, J. Jared
AU - Schreck, Carl J., III
AU - Sun, Fengying
AU - Vose, Russell
AU - Williams, Claude N.
AU - Yin, Xungang
AU - Zhang, Huai-Min
T2 - JOURNAL OF CLIMATE
AB - Abstract This analysis estimates uncertainty in the NOAA global surface temperature (GST) version 5 (NOAAGlobalTemp v5) product, which consists of sea surface temperature (SST) from the Extended Reconstructed SST version 5 (ERSSTv5) and land surface air temperature (LSAT) from the Global Historical Climatology Network monthly version 4 (GHCNm v4). Total uncertainty in SST and LSAT consists of parametric and reconstruction uncertainties. The parametric uncertainty represents the dependence of SST/LSAT reconstructions on selecting 28 (6) internal parameters of SST (LSAT), and is estimated by a 1000-member ensemble from 1854 to 2016. The reconstruction uncertainty represents the residual error of using a limited number of 140 (65) modes for SST (LSAT). Uncertainty is quantified at the global scale as well as the local grid scale. Uncertainties in SST and LSAT at the local grid scale are larger in the earlier period (1880s–1910s) and during the two world wars due to sparse observations, then decrease in the modern period (1950s–2010s) due to increased data coverage. Uncertainties in SST and LSAT at the global scale are much smaller than those at the local grid scale due to error cancellations by averaging. Uncertainties are smaller in SST than in LSAT due to smaller SST variabilities. Comparisons show that GST and its uncertainty in NOAAGlobalTemp v5 are comparable to those in other internationally recognized GST products. The differences between NOAAGlobalTemp v5 and other GST products are within their uncertainties at the 95% confidence level.
DA - 2020/2//
PY - 2020/2//
DO - 10.1175/JCLI-D-19-0395.1
VL - 33
IS - 4
SP - 1351-1379
SN - 1520-0442
KW - Sea surface temperature
KW - Climate change
KW - Surface temperature
KW - Climate records
KW - Climate variability
ER -
TY - JOUR
TI - Precipitation Extremes: Trends and Relationships with Average Precipitation and Precipitable Water in the Contiguous United States
AU - Kunkel, Kenneth E.
AU - Karl, Thomas R.
AU - Squires, Michael F.
AU - Yin, Xungang
AU - Stegall, Steve T.
AU - Easterling, David R.
T2 - JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY
AB - Abstract Trends of extreme precipitation (EP) using various combinations of average return intervals (ARIs) of 1, 2, 5, 10, and 20 years with durations of 1, 2, 5, 10, 20, and 30 days were calculated regionally across the contiguous United States. Changes in the sign of the trend of EP vary by region as well as by ARI and duration, despite the statistically significant upward trends for all combinations of EP thresholds when area averaged across the contiguous United States. Spatially, there is a pronounced east-to-west gradient in the trends of the EP with strong upward trends east of the Rocky Mountains. In general, upward trends are larger and more significant for longer ARIs, but the contribution to the trend in total seasonal and annual precipitation is significantly larger for shorter ARIs because they occur more frequently. Across much of the contiguous United States, upward trends of warm-season EP are substantially larger than those for the cold season and have a substantially greater effect on the annual trend in total precipitation. This result occurs even in areas where the total precipitation is nearly evenly divided between the cold and warm seasons. When compared with short-duration events, long-duration events—for example, 30 days—contribute the most to annual trends. Coincident statistically significant upward trends of EP and precipitable water (PW) occur in many regions, especially during the warm season. Increases in PW are likely to be one of several factors responsible for the increase in EP (and average total precipitation) observed in many areas across the contiguous United States.
DA - 2020/1//
PY - 2020/1//
DO - 10.1175/JAMC-D-19-0185.1
VL - 59
IS - 1
SP - 125-142
SN - 1558-8432
KW - Climate change
KW - Climate variability
ER -
TY - JOUR
TI - Modeling and measurements of ammonia from poultry operations: Their emissions, transport, and deposition in the Chesapeake Bay
AU - Baker, Jordan
AU - Battye, William H.
AU - Robarge, Wayne
AU - Arya, S. Pal
AU - Aneja, Viney P.
T2 - SCIENCE OF THE TOTAL ENVIRONMENT
DA - 2020/3/1/
PY - 2020/3/1/
DO - 10.1016/j.scitotenv.2019.1115290
VL - 706
SP -
SN - 1879-1026
KW - Ammonia deposition
KW - Delmarva Peninsula
KW - Chesapeake Bay
KW - Poultry
KW - CAFO
ER -
TY - JOUR
TI - Spatial patterns in dissolved organic matter composition controlled by watershed characteristics in a coastal river network: The Neuse River Basin, USA
AU - Bhattacharya, Ruchi
AU - Osburn, Christopher L.
T2 - Water Research
AB - The effect of watershed characteristics (land use land cover and morphology) on spatial variability in dissolved organic matter (DOM) composition, and concentrations of dissolved organic carbon [DOC] and nitrogen [DON] was assessed in a coastal river basin draining into Pamlico Sound in eastern North Carolina, USA. Understanding the factors that influence DOM concentration and composition i.e., structurally complex molecules with high molecular weight versus low molecular weight, simple molecules can provide insights on DOM cycling and water composition implications. Such information is imperative for large coastal river networks undergoing rapid and intense land use and land cover (LULC) changes. DOM composition was estimated using optical indices calculated from DOM absorbance and fluorescence measurements. DOM was derived from terrestrial sources, and ordination analysis indicated that LULC, in particular, % wetland area was the most significant control on DOM composition and concentration. Wetland and agricultural coastal streams were abundant in humic and complex DOM, whereas forested and urban streams were least abundant in humic DOM. We speculate that greater availability of mobilizable DOM in wetland and agricultural watersheds contributed to this observation. In comparison, mixed urbanized and forested streams in North Carolina's Piedmont region were abundant in [DOC], less complex, low molecular weight DOM, as well as greater amounts [DON] due to higher urban runoff and elevated DOM production in these streams. Our results indicated that physiographic transition from Piedmont to coastal plain and varying LULC influenced the spatial variability in DOM composition and concentration. Our findings highlight that increasing anthropogenic alterations might increase the abundance of reactive DOM in coastal rivers and estuaries resulting in severe water quality issues. This information is important for monitoring and developing land use policies.
DA - 2020/2//
PY - 2020/2//
DO - 10.1016/j.watres.2019.115248
VL - 169
SP - 115248
J2 - Water Research
LA - en
OP -
SN - 0043-1354
UR - http://dx.doi.org/10.1016/j.watres.2019.115248
DB - Crossref
KW - Dissolved organic matter
KW - Coastal ecosystem
KW - River network
KW - Watershed characteristics
KW - Land use land cover
KW - Organic matter composition
KW - Water quality monitoring
ER -
TY - JOUR
TI - Evaluation and uncertainty investigation of the NO2, CO and NH3 modeling over China under the framework of MICS-Asia III
AU - Kong, Lei
AU - Tang, Xiao
AU - Zhu, Jiang
AU - Wang, Zifa
AU - Fu, Joshua S.
AU - Wang, Xuemei
AU - Itahashi, Syuichi
AU - Yamaji, Kazuyo
AU - Nagashima, Tatsuya
AU - Lee, Hyo-Jung
AU - Kim, Cheol-Hee
AU - Lin, Chuan-Yao
AU - Chen, Lei
AU - Zhang, Meigen
AU - Tao, Zhining
AU - Li, Jie
AU - Kajino, Mizuo
AU - Liao, Hong
AU - Wang, Zhe
AU - Sudo, Kengo
AU - Wang, Yuesi
AU - Pan, Yuepeng
AU - Tang, Guiqian
AU - Li, Meng
AU - Wu, Qizhong
AU - Ge, Baozhu
AU - Carmichael, Gregory R.
T2 - ATMOSPHERIC CHEMISTRY AND PHYSICS
AB - Abstract. Despite the significant progress in improving chemical transport models (CTMs), applications of these modeling endeavors are still subject to large and complex model uncertainty. The Model Inter-Comparison Study for Asia III (MICS-Asia III) has provided the opportunity to assess the capability and uncertainty of current CTMs in East Asian applications. In this study, we have evaluated the multi-model simulations of nitrogen dioxide (NO2), carbon monoxide (CO) and ammonia (NH3) over China under the framework of MICS-Asia III. A total of 13 modeling results, provided by several independent groups from different countries and regions, were used in this study. Most of these models used the same modeling domain with a horizontal resolution of 45 km and were driven by common emission inventories and meteorological inputs. New observations over the North China Plain (NCP) and Pearl River Delta (PRD) regions were also available in MICS-Asia III, allowing the model evaluations over highly industrialized regions. The evaluation results show that most models captured the monthly and spatial patterns of NO2 concentrations in the NCP region well, though NO2 levels were slightly underestimated. Relatively poor performance in NO2 simulations was found in the PRD region, with larger root-mean-square error and lower spatial correlation coefficients, which may be related to the coarse resolution or inappropriate spatial allocations of the emission inventories in the PRD region. All models significantly underpredicted CO concentrations in both the NCP and PRD regions, with annual mean concentrations that were 65.4 % and 61.4 % underestimated by the ensemble mean. Such large underestimations suggest that CO emissions might be underestimated in the current emission inventory. In contrast to the good skills for simulating the monthly variations in NO2 and CO concentrations, all models failed to reproduce the observed monthly variations in NH3 concentrations in the NCP region. Most models mismatched the observed peak in July and showed negative correlation coefficients with the observations, which may be closely related to the uncertainty in the monthly variations in NH3 emissions and the NH3 gas–aerosol partitioning. Finally, model intercomparisons have been conducted to quantify the impacts of model uncertainty on the simulations of these gases, which are shown to increase with the reactivity of species. Models contained more uncertainty in the NH3 simulations. This suggests that for some highly active and/or short-lived primary pollutants, like NH3, model uncertainty can also take a great part in the forecast uncertainty in addition to the emission uncertainty. Based on these results, some recommendations are made for future studies.
DA - 2020/1/6/
PY - 2020/1/6/
DO - 10.5194/acp-20-181-2020
VL - 20
IS - 1
SP - 181-202
SN - 1680-7324
ER -
TY - JOUR
TI - JA&WMA dedicates this issue to its outstanding reviewers and editors
AU - Rao, S. Trivikrama
T2 - JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION
DA - 2020/1/2/
PY - 2020/1/2/
DO - 10.1080/10962247.2019.1685287
VL - 70
IS - 1
SP - 1-1
SN - 2162-2906
ER -
TY - JOUR
TI - What Drives Upper-Ocean Temperature Variability in Coupled Climate Models and Observations?
AU - Small, R. Justin
AU - Bryan, Frank O.
AU - Bishop, Stuart P.
AU - Larson, Sarah
AU - Tomas, Robert
T2 - JOURNAL OF CLIMATE
AB - Abstract A key question in climate modeling is to what extent sea surface temperature and upper-ocean heat content are driven passively by air–sea heat fluxes, as opposed to forcing by ocean dynamics. This paper investigates the question using a climate model at different resolutions, and observations, for monthly variability. At the grid scale in a high-resolution climate model with resolved mesoscale ocean eddies, ocean dynamics (i.e., ocean heat flux convergence) dominates upper 50 m heat content variability over most of the globe. For deeper depths of integration to 400 m, the heat content variability at the grid scale is almost totally controlled by ocean heat flux convergence. However, a strong dependence on spatial scale is found—for the upper 50 m of ocean, after smoothing the data to around 7°, air–sea heat fluxes, augmented by Ekman heat transports, dominate. For deeper depths of integration to 400 m, the transition scale becomes larger and is above 10° in western boundary currents. Comparison of climate model results with observations show that the small-scale influence of ocean intrinsic variability is well captured by the high-resolution model but is missing from a comparable model with parameterized ocean-eddy effects. In the deep tropics, ocean dynamics dominates in all cases and all scales. In the subtropical gyres at large scales, air–sea heat fluxes play the biggest role. In the midlatitudes, at large scales >10°, atmosphere-driven air–sea heat fluxes and Ekman heat transport variability are the dominant processes except in the western boundary currents for the 400 m heat content.
DA - 2020/1//
PY - 2020/1//
DO - 10.1175/JCLI-D-19-0295.1
VL - 33
IS - 2
SP - 577-596
SN - 1520-0442
KW - Ocean dynamics
KW - Atmosphere-ocean interaction
KW - Climate models
ER -
TY - JOUR
TI - Simulated Evolution and Severe Wind Production by the 25-26 June 2015 Nocturnal MCS from PECAN
AU - Parker, Matthew D.
AU - Borchardt, Brett S.
AU - Miller, Rachel L.
AU - Ziegler, Conrad L.
T2 - MONTHLY WEATHER REVIEW
AB - Abstract The 25–26 June 2015 nocturnal mesoscale convective system (MCS) from the Plains Elevated Convection at Night (PECAN) field project produced severe winds within an environment that might customarily be associated with elevated convection. This work incorporates both a full-physics real-world simulation and an idealized single-sounding simulation to explore the MCS’s evolution. Initially, the simulated convective systems were elevated, being maintained by wavelike disturbances and lacking surface cold pools. As the systems matured, surface outflows began to appear, particularly where heavy precipitation was occurring, with air in the surface cold pools originating from up to 4–5 km AGL. Via this progression, the MCSs exhibited a degree of self-organization (i.e., structures that are dependent upon an MCS’s particular history). The cold pools eventually became 1.5–3.5 km deep, by which point passive tracers revealed that the convection was at least partly surface based. Soon after becoming surface based, both simulations produced severe surface winds, the strongest of which were associated with embedded low-level mesovortices and their attendant outflow surges and bowing segments. The origin of the simulated mesovortices was likely the downward tilting of system-generated horizontal vorticity (from baroclinity, but also possibly friction) within the simulated MCSs’ outflow, as has been argued in a number of previous studies. Taken altogether, it appears that severe nocturnal MCSs may often resemble their cold pool-driven, surface-based afternoon counterparts.
DA - 2020/1//
PY - 2020/1//
DO - 10.1175/MWR-D-19-0072.1
VL - 148
IS - 1
SP - 183-209
SN - 1520-0493
KW - Convection lines
KW - Convective storms
KW - systems
KW - Convective-scale processes
KW - Mesoscale processes
KW - Mesoscale systems
KW - Cloud resolving models
ER -
TY - JOUR
TI - A New Variable-Threshold Persistent Anomaly Index: Northern Hemisphere Anomalies in the ERA-Interim Reanalysis
AU - Miller, Rebecca L.
AU - Lackmann, Gary M.
AU - Robinson, Walter A.
T2 - MONTHLY WEATHER REVIEW
AB - Abstract Persistent weather regimes characterized by anomalous temperature or precipitation are often associated with persistent anomalies (PAs) in the tropospheric geopotential height field. To identify PAs throughout the annual cycle, an earlier definition is modified to apply a seasonally varying magnitude threshold, based on a smoothed, daily varying climatological average of daily 500-hPa geopotential height variability. The modified index can be applied to a wide variety of analysis, reanalysis, or model-forecast gridded data. Here, the modified PA index is used to identify positive and negative Northern Hemisphere PAs in all seasons and to compute trends in PA frequency, strength, location, and duration, in the ECMWF ERA-Interim reanalysis dataset (1979–2016). Height data are detrended and anomalies are weighted with an inverse sine-of-latitude function. In addition to maxima in PA frequency identified previously (North Pacific, North Atlantic, and Russia), an additional summertime maximum appears in the Arctic; this feature has not been analyzed extensively. A composite of summertime positive Arctic PA events reveals an equivalent barotropic structure, similar to that documented for midlatitude PAs. Arctic PA frequency is greatest in summer; it exhibits no trend in frequency over the 38-yr ERA-Interim analysis period. In fact, no discernable trends in PA frequency, strength, or duration are evident in the analysis period for the primary PA regions, although there is a suggestion of a northward shift in positive PA activity in the North Pacific.
DA - 2020/1//
PY - 2020/1//
DO - 10.1175/MWR-D-19-0144.1
VL - 148
IS - 1
SP - 43-62
SN - 1520-0493
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85082885384&partnerID=MN8TOARS
KW - Blocking
KW - Storm tracks
ER -
TY - JOUR
TI - Wetland Conditions Differentially Influence Nitrogen Processing within Waterfowl Impoundments
AU - Hinckley, Brian R.
AU - Etheridge, J. Randall
AU - Peralta, Ariane L.
T2 - WETLANDS
DA - 2020/10//
PY - 2020/10//
DO - 10.1007/s13157-019-01246-8
VL - 40
IS - 5
SP - 1117-1131
SN - 1943-6246
KW - Denitrification
KW - Hydrologic management
KW - Mineralization
KW - Nitrification
ER -
TY - JOUR
TI - A multi-institutional study of inquiry-based lab activities using the Augmented Reality Sandbox: impacts on undergraduate student learning
AU - McNeal, Karen S.
AU - Ryker, Katherine
AU - Whitmeyer, Shelley
AU - Giorgis, Scott
AU - Atkins, Rachel
AU - LaDue, Nicole
AU - Clark, Christine
AU - Soltis, Nick
AU - Pingel, Thomas
T2 - JOURNAL OF GEOGRAPHY IN HIGHER EDUCATION
AB - We developed and tested different pedagogical treatments using an Augmented Reality (AR) Sandbox to teach introductory geoscience students about reading topographic maps at five institutions in both pilot and full implementation studies. The AR Sandbox treatments were characterized as 1) unstructured play, 2) a semi-structured lesson, and 3) a structured lesson. The success of each was contrasted with the control condition of a traditional topographic map lab without the AR Sandbox. Students completed a subset of questions from the Topographic Maps Assessment (TMA) and a series of mental rotation questions post-implementation. No significant differences were found on TMA post-test scores between groups who used the unstructured Sandbox play treatment compared to the control condition. Semi-structured and structured lesson formats similarly failed to produce a statistically significant difference on the TMA post-test. This indicates that no single treatment worked universally better than another. However, regression analysis showed two factors significantly predicted performance on the TMA, including spatial performance and self-assessed knowledge (or confidence) of topographic maps. Of the groups that used the Sandbox, students with low and high scores on the mental rotation test performed best on the TMA following the structured treatment.
DA - 2020/1/2/
PY - 2020/1/2/
DO - 10.1080/03098265.2019.1694875
VL - 44
IS - 1
SP - 85-107
SN - 1466-1845
KW - Visualization
KW - spatial thinking
KW - mixed reality
KW - topographic maps
KW - pedagogy
ER -
TY - JOUR
TI - Investigating the association between late spring Gulf of Mexico sea surface temperatures and US Gulf Coast precipitation extremes with focus on Hurricane Harvey
AU - Russell, Brook T.
AU - Risser, Mark D.
AU - Smith, Richard L.
AU - Kunkel, Kenneth E.
T2 - ENVIRONMETRICS
AB - Abstract Hurricane Harvey brought extreme levels of rainfall to the Houston, Texas, area over a 7‐day period in August 2017, resulting in catastrophic flooding that caused loss of human life and damage to personal property and public infrastructure. In the wake of this event, there has been interest in understanding the degree to which this event was unusual and estimating the probability of experiencing a similar event in other locations. Additionally, researchers have aimed to better understand the ways in which the sea surface temperature (SST) in the Gulf of Mexico (GoM) is associated with precipitation extremes in this region. This work addresses all of these issues through the development of a multivariate spatial extreme value model. Our analysis indicates that warmer GoM SSTs are associated with higher precipitation extremes in the western Gulf Coast region during hurricane season and that the precipitation totals observed during Hurricane Harvey are less unusual based on the warm GoM SST in 2017. As SSTs in the GoM are expected to steadily increase over the remainder of this century, this analysis suggests that western Gulf Coast locations may experience more severe precipitation extremes during hurricane season.
DA - 2020/3//
PY - 2020/3//
DO - 10.1002/env.2595
VL - 31
IS - 2
SP -
SN - 1099-095X
KW - coregionalization
KW - covariance tapering
KW - generalized extreme value distribution
KW - multivariate spatial modeling
KW - precipitation return levels
ER -