@article{leeper_matthews_cesarini_bell_2021, title={Evaluation of Air and Soil Temperatures for Determining the Onset of Growing Season}, volume={126}, ISSN={["2169-8961"]}, DOI={10.1029/2020JG006171}, abstractNote={While air temperature has commonly been used to define the onset of the growing season (plant uptake of soil nutrients), there is evidence in the literature suggesting vegetation growth is sensitive to soil temperature. As soil temperature observations become increasingly available from monitoring networks, differences in the start of season (SOS) estimates based on both above and below-ground temperatures should be explored. In this study, air, surface, and soil (at depths of 5, 10, and 20 cm) temperature from the U.S. Climate Reference Network were used to estimate SOS at 104 stations across the U.S.. Temperature thresholds of 0, 5, or 10°C were used to estimate the SOS as the earliest date of the year when temperatures remained above each threshold. SOS dates based on temperature were compared with MODIS-satellite-derived normalized difference vegetation index (NDVI). Results indicated that the day-of-year of SOS based on soil temperature occurred about two months earlier than SOS estimates from air and surface temperatures. Overall, 5 cm soil temperature SOS estimates using a 5°C threshold matched well with SOSNDVI; albeit, only slightly better than air temperature SOS estimates using the 0°C threshold. This was in part because air temperature conditions were more likely to dip back below a given threshold with the passage cold fronts than soil temperatures. This often resulted in later air temperature SOS estimates particularly in years with sub-freezing late season cold fronts. This suggests soil temperature can improve SOS estimates for many locations across the U.S.}, number={8}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES}, author={Leeper, Ronald D. and Matthews, Jessica L. and Cesarini, Maria S. and Bell, Jesse E.}, year={2021}, month={Aug} }
 @article{leeper_bell_palecki_2019, title={A Description and Evaluation of US Climate Reference Network Standardized Soil Moisture Dataset}, volume={58}, ISSN={["1558-8432"]}, DOI={10.1175/JAMC-D-18-0269.1}, abstractNote={Abstract The interpretation of in situ or remotely sensed soil moisture data for drought monitoring is challenged by the sensitivity of these observations to local soil characteristics and seasonal precipitation patterns. These challenges can be overcome by standardizing soil moisture observations. Traditional approaches require a lengthy record (usually 30 years) that most soil monitoring networks lack. Sampling techniques that combine hourly measurements over a temporal window have been used in the literature to generate historical references (i.e., climatology) from shorter-term datasets. This sampling approach was validated on select U.S. Department of Agriculture Soil Climate Analysis Network (SCAN) stations using a Monte Carlo analysis, which revealed that shorter-term (5+ years) hourly climatologies were similar to longer-term (10+ year) hourly means. The sampling approach was then applied to soil moisture observations from the U.S. Climate Reference Network (USCRN). The sampling method was used to generate multiple measures of soil moisture (mean and median anomalies, standardized median anomaly by interquantile range, and volumetric) that were converted to percentiles using empirical cumulative distribution functions. Overall, time series of soil moisture percentile were very similar among the differing measures; however, there were times of year at individual stations when soil moisture percentiles could have substantial deviations. The use of soil moisture percentiles and counts of threshold exceedance provided more consistent measures of hydrological conditions than observed soil moisture. These results suggest that hourly soil moisture observations can be reasonably standardized and can provide consistent measures of hydrological conditions across spatial and temporal scales.}, number={7}, journal={JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY}, author={Leeper, Ronald D. and Bell, Jesse E. and Palecki, Michael A.}, year={2019}, month={Jul}, pages={1417–1428} }
 @article{rennie_bell_kunkel_herring_cullen_abadi_2019, title={Development of a Submonthly Temperature Product to Monitor Near-Real-Time Climate Conditions and Assess Long-Term Heat Events in the United States}, volume={58}, ISSN={["1558-8432"]}, DOI={10.1175/JAMC-D-19-0076.1}, abstractNote={Abstract Land surface air temperature products have been essential for monitoring the evolution of the climate system. Before a temperature dataset is included in such analyses, it is important that nonclimatic influences be removed or changed so that the dataset is considered to be homogenous. These inhomogeneities include changes in station location, instrumentation, and observing practices. Many homogenized products exist on the monthly time scale, but few daily and weekly products exist. Recently, a submonthly homogenized dataset has been developed using data and software from NOAA’s National Centers for Environmental Information. Homogeneous daily data are useful for identification and attribution of extreme heat events. Projections of increasing temperatures are expected to result in corresponding increases in the frequency, duration, and intensity of such events. It is also established that heat events can have significant public health impacts, including increases in mortality and morbidity. The method to identify extreme heat events using daily homogeneous temperature data is described and used to develop a climatology of heat event onset, length, and severity. This climatology encompasses nearly 3000 extreme maximum and minimum temperature events across the United States since 1901. A sizeable number of events occurred during the Dust Bowl period of the 1930s; however, trend analysis shows an increase in heat event number and length since 1951. Overnight extreme minimum temperature events are increasing more than daytime maximum temperatures, and regional analysis shows that events are becoming much more prevalent in the western and southeastern parts of the United States.}, number={12}, journal={JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY}, author={Rennie, Jared and Bell, Jesse E. and Kunkel, Kenneth E. and Herring, Stephanie and Cullen, Heidi and Abadi, Azar M.}, year={2019}, month={Dec}, pages={2653–2674} }
 @misc{bell_brown_conlon_herring_kunkel_lawrimore_luber_schreck_smith_uejio_2018, title={Changes in extreme events and the potential impacts on human health}, volume={68}, ISSN={["2162-2906"]}, DOI={10.1080/10962247.2017.1401017}, abstractNote={Extreme weather and climate-related events affect human health by causing death, injury, and illness, as well as having large socioeconomic impacts. Climate change has caused changes in extreme event frequency, intensity, and geographic distribution, and will continue to be a driver for change in the future. Some of these events include heat waves, droughts, wildfires, dust storms, flooding rains, coastal flooding, storm surges, and hurricanes. The pathways connecting extreme events to health outcomes and economic losses can be diverse and complex. The difficulty in predicting these relationships comes from the local societal and environmental factors that affect disease burden. More information is needed about the impacts of climate change on public health and economies to effectively plan for and adapt to climate change. This paper describes some of the ways extreme events are changing and provides examples of the potential impacts on human health and infrastructure. It also identifies key research gaps to be addressed to improve the resilience of public health to extreme events in the future.Extreme weather and climate events affect human health by causing death, injury, and illness, as well as having large socioeconomic impacts. Climate change has caused changes in extreme event frequency, intensity, and geographic distribution, and will continue to be a driver for change in the future. Some of these events include heat waves, droughts, wildfires, flooding rains, coastal flooding, surges, and hurricanes. The pathways connecting extreme events to health outcomes and economic losses can be diverse and complex. The difficulty in predicting these relationships comes from the local societal and environmental factors that affect disease burden.}, number={4}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Bell, Jesse E. and Brown, Claudia Langford and Conlon, Kathryn and Herring, Stephanie and Kunkel, Kenneth E. and Lawrimore, Jay and Luber, George and Schreck, Carl and Smith, Adam and Uejio, Christopher}, year={2018}, pages={265–287} }
 @article{leeper_bell_vines_palecki_2017, title={An Evaluation of the North American Regional Reanalysis Simulated Soil Moisture Conditions during the 2011-13 Drought Period}, volume={18}, ISSN={["1525-7541"]}, DOI={10.1175/jhm-d-16-0132.1}, abstractNote={Abstract Accurate and timely information on soil moisture conditions is an important component to effectively prepare for the damaging aspects of hydrological extremes. The combination of sparsely dense in situ networks and shallow observation depths of remotely sensed soil moisture conditions often force local and regional decision-makers to rely on numerical methods when assessing the current soil state. In this study, soil moisture from a commonly used, high-resolution reanalysis dataset is compared to observations from the U.S. Climate Reference Network (USCRN). The purpose of this study is to evaluate how well the North American Regional Reanalysis (NARR) captured the evolution, intensity, and spatial extent of the 2012 drought using both raw volumetric values and standardized anomalies of soil moisture. Comparisons revealed that despite a dry precipitation bias of 22% nationally, NARR had predominantly wetter 5-cm volumetric soil conditions over the growing season (April–September) than observed at USCRN sites across the contiguous United States, with differences more pronounced in drier regions. These biases were partially attributed to differences between the dominant soil characteristics assigned to the modeled grid cells and localized soil characteristics at the USCRN stations. However, NARR was able to successfully capture many aspects of the 2012 drought, including the timing, intensity, and spatial extent when using standardized soil moisture anomalies. Standardizing soil moisture conditions reduced the magnitude of systematic biases between NARR and USCRN in many regions and provided a more robust basis for utilizing modeled soil conditions in assessments of hydrological extremes.}, number={2}, journal={JOURNAL OF HYDROMETEOROLOGY}, author={Leeper, Ronald D. and Bell, Jesse E. and Vines, Chante and Palecki, Michael}, year={2017}, month={Feb}, pages={515–527} }
 @article{shriber_conlon_benedict_mccotter_bell_2017, title={Assessment of vulnerability to coccidioidomycosis in Arizona and California}, volume={14}, number={7}, journal={International Journal of Environmental Research and Public Health}, author={Shriber, J. and Conlon, K. C. and Benedict, K. and McCotter, O. Z. and Bell, J. E.}, year={2017} }
 @misc{lakind_overpeck_breysse_backer_richardson_sobus_sapkota_upperman_jiang_ben beard_et al._2016, title={Exposure science in an age of rapidly changing climate: Challenges and opportunities}, volume={26}, number={6}, journal={Journal of Exposure Science and Environmental Epidemiology}, author={LaKind, J. S. and Overpeck, J. and Breysse, P. N. and Backer, L. and Richardson, S. D. and Sobus, J. and Sapkota, A. and Upperman, C. R. and Jiang, C. S. and Ben Beard, C. and et al.}, year={2016}, pages={529–538} }
 @article{wilson_baker_meyers_kochendorfer_hall_bell_diamond_palecki_2016, title={Site-specific soil properties of the US climate reference network soil moisture}, volume={15}, number={11}, journal={Vadose Zone Journal}, author={Wilson, T. B. and Baker, C. B. and Meyers, T. P. and Kochendorfer, J. and Hall, M. and Bell, J. E. and Diamond, H. J. and Palecki, M. A.}, year={2016} }
 @article{bilotta_bell_shepherd_arguez_2015, title={Calculation and evaluation of an air-freezing index for the 1981-2010 climate normals period in the coterminous united states}, volume={54}, number={1}, journal={Journal of Applied Meteorology and Climatology}, author={Bilotta, R. and Bell, J. E. and Shepherd, E. and Arguez, A.}, year={2015}, pages={69–76} }
 @article{bell_leeper_palecki_coopersmith_wilson_bilotta_embler_2015, title={Evaluation of the 2012 Drought with a Newly Established National Soil Monitoring Network}, volume={14}, ISSN={["1539-1663"]}, DOI={10.2136/vzj2015.02.0023}, abstractNote={Core Ideas New US soil moisture network provides new opportunity to evaluate drought Soil moisture at deeper depths did not fully recover from the 2012 drought in 2013 Soil moisture varied by region in the response to drought The NOAA United States Climate Reference Network (USCRN) deployed soil moisture sensors during 2009 to 2011 to monitor the temporal and spatial variability of soil moisture at 114 locations in the contiguous United States. These new soil observations will enhance our understanding of changing soil conditions for better drought monitoring. One year after full deployment of the network, a large drought occurred across most of the United States and provided an opportunity to evaluate the utility of this network for drought monitoring. The soil moisture signal of the 2012 drought in the continental United States was detected nationally at all observational depths (5, 10, 20, 50, and 100 cm), with an overall 11.07% decrease from the average of the 2011 to 2013 summers. The top three depths (5, 10, and 20 cm) experienced the largest decrease in soil moisture. Although 2013 national precipitation totals returned to normal values and national soil moisture levels recovered from the 2012 drought, the national average soil moisture concentrations combined at the 50- and 100-cm depths remained around 18% below pre-drought levels. Regional analysis of the 2012 drought identified that the Upper Midwest, Northeast, Northern Rockies and Plains, and Ohio Valley climate regions were most impacted and demonstrated a temporal pattern similar to the national analysis. These results demonstrate the utility of using USCRN for monitoring national soil moisture conditions, assessing droughts, and tracking climate change with time.}, number={11}, journal={VADOSE ZONE JOURNAL}, author={Bell, Jesse E. and Leeper, Ronald D. and Palecki, Michael A. and Coopersmith, Evan and Wilson, Tim and Bilotta, Rocky and Embler, Scott}, year={2015}, month={Nov} }
 @article{coopersmith_bell_cosh_2015, title={Extending the soil moisture data record of the US Climate Reference Network (USCRN) and Soil Climate Analysis Network (SCAN)}, volume={79}, journal={Advances in Water Resources}, author={Coopersmith, E. J. and Bell, J. E. and Cosh, M. H.}, year={2015}, pages={80–90} }
 @article{yan_luo_sherry_bell_zhou_xia_2014, title={Rain use efficiency as affected by climate warming and biofuel harvest: results from a 12-year field experiment}, volume={6}, number={5}, journal={Global Change Biology Bioenergy}, author={Yan, L. M. and Luo, Y. Q. and Sherry, R. A. and Bell, J. E. and Zhou, X. H. and Xia, J. Y.}, year={2014}, pages={556–565} }
 @article{bell_palecki_baker_collins_lawrimore_leeper_hall_kochendorfer_meyers_wilson_et al._2013, title={U.S. climate reference network soil moisture and temperature observations}, volume={14}, number={3}, journal={Journal of Hydrometeorology}, author={Bell, J. E. and Palecki, M. A. and Baker, C. B. and Collins, W. G. and Lawrimore, J. H. and Leeper, R. D. and Hall, M. E. and Kochendorfer, J. and Meyers, T. P. and Wilson, T. and et al.}, year={2013}, pages={977–988} }
 @article{palecki_bell_2013, title={U.S. climate reference network soil moisture observations with triple redundancy: Measurement variability}, volume={12}, number={2}, journal={Vadose Zone Journal}, author={Palecki, M. A. and Bell, J. E.}, year={2013} }