@article{turnau_robinson_lackmann_michaelis_2022, title={Model Projections of Increased Severity of Heat Waves in Eastern Europe}, volume={49}, ISSN={["1944-8007"]}, url={https://doi.org/10.1029/2022GL100183}, DOI={10.1029/2022GL100183}, abstractNote={AbstractExtreme heat is investigated in a series of high‐resolution time‐slice global simulations comparing the current and late‐21st century climates. An increase in climate‐relative extreme heat is found in the region surrounding the Black Sea. Similarities between the synoptic‐scale flows in current and future heat events combined with a decrease in future summer precipitation suggests that the increased future severity stems from strengthened land‐atmosphere feedbacks driven primarily by the changes in precipitation. The resulting intensification of heat events beyond the mean warming driven by climate change could generate significant future heat hazards in vulnerable regions. Given the continental cool bias in the present‐day simulations, the resulting estimates of future extreme heat are likely to be conservative.}, number={22}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Turnau, Roger and Robinson, Walter A. A. and Lackmann, Gary M. M. and Michaelis, Allison C. C.}, year={2022}, month={Nov} }
 @article{lackmann_miller_robinson_michaelis_2021, title={Persistent Anomaly Changes in High-Resolution Climate Simulations}, volume={34}, ISSN={["1520-0442"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85106939084&partnerID=MN8TOARS}, DOI={10.1175/JCLI-D-20-0465.1}, abstractNote={AbstractPersistent anomalies (PAs) are associated with a variety of impactful weather extremes, prompting research into how their characteristics will respond to climate change. Previous studies, however, have not provided conclusive results, owing to the complexity of the phenomenon and to difficulties in general circulation model (GCM) representations of PAs. Here, we diagnose PA activity in ten years of current and projected future output from global, high-resolution (15-km mesh) time-slice simulations performed with the Model for Prediction Across Scales-Atmosphere (MPAS-A). These time slices span a range of ENSO states. They include high-resolution representations of sea-surface temperatures and GCM-based sea ice for present and future climates. Future projections, based on the RCP8.5 scenario, exhibit strong Arctic amplification and tropical upper warming, providing a valuable experiment with which to assess the impact of climate change on PA frequency. The MPAS-A present-climate simulations reproduce the main centers of observed PA activity, but with an eastward shift in the North Pacific and reduced amplitude in the North Atlantic. The overall frequency of positive PAs in the future simulations is similar to that in the present-day simulations, while negative PAs become less frequent. Although some regional changes emerge, the small, generally negative changes in PA frequency and meridional circulation index indicate that climate change does not lead to increased persistence of midlatitude flow anomalies or increased waviness in these simulations.}, number={13}, journal={JOURNAL OF CLIMATE}, author={Lackmann, Gary M. and Miller, Rebecca L. and Robinson, Walter A. and Michaelis, Allison C.}, year={2021}, month={Jul}, pages={5425–5442} }
 @article{michaelis_lackmann_2021, title={Storm-Scale Dynamical Changes of Extratropical Transition Events in Present-Day and Future High-Resolution Global Simulations}, volume={34}, ISSN={["1520-0442"]}, DOI={10.1175/JCLI-D-20-0472.1}, abstractNote={AbstractTropical cyclones (TCs) propagating into baroclinic midlatitude environments can transform into extratropical cyclones, in some cases resulting in high-impact weather conditions far from the tropics. This study extends analysis of extratropical transition (ET) changes in multiseasonal global simulations using the Model for Prediction Across Scales–Atmosphere (MPAS-A) under present-day and projected future conditions. High resolution (15 km) covers the Northern Hemisphere; TCs and ET events are tracked based on sea level pressure minima accompanied by a warm core and use of a cyclone phase space method. Previous analysis of these simulations showed large changes in ET over the North Atlantic (NATL) basin, with ET events exhibiting a 4°–5° northward latitudinal shift and ~6-hPa strengthening of the post-transition extratropical cyclone. Storm-relative composites, primarily representing post-transformation cold-core events, indicate that this increase in post-transition storm intensity is associated with an intensification of the neighboring upper-level trough and downstream ridge, and a poleward shift in the storm center, conducive to enhanced trough–TC interactions after ET completion. Additionally, the future composite ET event is located in the right-jet entrance of an outflow jet that is strengthened relative to its present-day counterpart. Localized impacts associated with ET events, such as heavy precipitation and strong near-surface winds, are significantly enhanced in the future-climate simulations; 6-hourly precipitation for NATL events increases at a super-Clausius–Clapeyron rate with area-average precipitation increasing over 30%. Furthermore, intensified precipitation contributes to enhanced lower-tropospheric potential vorticity and stronger upper-tropospheric outflow, implying the potential for more extreme downstream impacts under the future climate scenario.}, number={12}, journal={JOURNAL OF CLIMATE}, author={Michaelis, Allison C. and Lackmann, Gary M.}, year={2021}, month={Jun}, pages={5037–5062} }
 @article{michaelis_lackmann_2019, title={Climatological Changes in the Extratropical Transition of Tropical Cyclones in High-Resolution Global Simulations}, volume={32}, ISSN={["1520-0442"]}, DOI={10.1175/JCLI-D-19-0259.1}, abstractNote={Abstract
               Tropical cyclones (TCs) undergoing extratropical transition (ET) can develop into intense cyclonic systems accompanied by high-impact weather in areas far removed from the original TC. This study presents an analysis of multiseasonal global simulations representative of present-day and projected future climates using the Model for Prediction Across Scales–Atmosphere (MPAS-A), with high resolution (15-km grid) throughout the Northern Hemisphere. TCs are tracked as minima in sea level pressure (SLP) accompanied by a warm core, and TC tracks are extended into the extratropical phase based on local minima in SLP and use of a cyclone phase space method. The present-day simulations adequately represent observed ET characteristics such as frequency, location, and seasonal cycles throughout the Northern Hemisphere. The most significant changes in future ET events occur in the North Atlantic (NATL) basin. Here, a more favorable background environment, a shift toward stronger TC warm cores in the lower troposphere, and a significant poleward shift in TC location lead to a ~40% increase in the number of NATL ET events and a ~6% increase in the fraction of TCs undergoing ET. This equates to approximately 1–2 additional ET events per year in this region. In the future simulations, ET in the NATL occurs markedly farther north by ~4°–5°N, and the resultant extratropical cyclones are stronger by ~6 hPa. These changes hold potentially important implications for areas directly affected by ET events, such as eastern North America, as well as for regions indirectly impacted by downstream effects, including western Europe.}, number={24}, journal={JOURNAL OF CLIMATE}, author={Michaelis, Allison C. and Lackmann, Gary M.}, year={2019}, month={Dec}, pages={8733–8753} }
 @article{michaelis_lackmann_robinson_2019, title={Evaluation of a unique approach to high-resolution climate modeling using the Model for Prediction Across Scales - Atmosphere (MPAS-A) version 5.1}, volume={12}, ISSN={["1991-9603"]}, url={https://doi.org/10.5194/gmd-12-3725-2019}, DOI={10.5194/gmd-12-3725-2019}, abstractNote={Abstract. We present multi-seasonal simulations representative of
present-day and future environments using the global Model for Prediction
Across Scales – Atmosphere (MPAS-A) version 5.1 with high resolution (15 km)
throughout the Northern Hemisphere. We select 10 simulation years with
varying phases of El Niño–Southern Oscillation (ENSO) and integrate each
for 14.5 months. We use analyzed sea surface temperature (SST) patterns for
present-day simulations. For the future climate simulations, we alter
present-day SSTs by applying monthly-averaged temperature changes derived
from a 20-member ensemble of Coupled Model Intercomparison Project phase 5
(CMIP5) general circulation models (GCMs) following the Representative
Concentration Pathway (RCP) 8.5 emissions scenario. Daily sea ice fields,
obtained from the monthly-averaged CMIP5 ensemble mean sea ice, are used for
present-day and future simulations. The present-day simulations provide a
reasonable reproduction of large-scale atmospheric features in the Northern
Hemisphere such as the wintertime midlatitude storm tracks,
upper-tropospheric jets, and maritime sea-level pressure features as well as
annual precipitation patterns across the tropics. The simulations also
adequately represent tropical cyclone (TC) characteristics such as strength,
spatial distribution, and seasonal cycles for most Northern Hemisphere
basins. These results demonstrate the applicability of these model
simulations for future studies examining climate change effects on various
Northern Hemisphere phenomena, and, more generally, the utility of MPAS-A
for studying climate change at spatial scales generally unachievable in
GCMs.
                    }, number={8}, journal={GEOSCIENTIFIC MODEL DEVELOPMENT}, publisher={Copernicus GmbH}, author={Michaelis, Allison C. and Lackmann, Gary M. and Robinson, Walter A.}, year={2019}, month={Aug}, pages={3725–3743} }
 @article{michaelis_willison_lackmann_robinson_2017, title={Changes in Winter North Atlantic Extratropical Cyclones in High-Resolution Regional Pseudo-Global Warming Simulations}, volume={30}, ISSN={["1520-0442"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027249354&partnerID=MN8TOARS}, DOI={10.1175/jcli-d-16-0697.1}, abstractNote={ The present study investigates changes in the location, frequency, intensity, and dynamical processes of North Atlantic extratropical cyclones with warming consistent with the IPCC Fifth Assessment Report (AR5) representative concentration pathway 8.5 (RCP8.5) scenario. The modeling, analysis, and prediction (MAP) climatology of midlatitude storminess (MCMS) feature-tracking algorithm was utilized to analyze 10 cold-season high-resolution atmospheric simulations over the North Atlantic region in current and future climates. Enhanced extratropical cyclone activity is most evident in the northeast North Atlantic and off the U.S. East Coast. These changes in cyclone activity are offset from changes in eddy kinetic energy and eddy heat flux. Investigation of the minimum SLP reached at each grid point reveals a lack of correspondence between the strongest events in the current and future simulations, indicating the future simulations produced a different population of storms. Examination of the percent change of storms in the storm-track region shows a reduction in the number of strong storms (i.e., those reaching a minimum SLP perturbation of at least −51 hPa). Storm-relative composites of strong and moderate storms show an increase in precipitation, associated with enhanced latent heat release and strengthening of the 900–700-hPa layer-average potential vorticity (PV). Other structural changes found for cyclones in a future climate include weakened upper-level PV for strong storms and a weakened near-surface potential temperature anomaly for moderate storms, demonstrating a change in storm dynamics. Furthermore, the impacts associated with extratropical cyclones, such as strong near-surface winds and heavy precipitation, strengthen and become more frequent with warming. }, number={17}, journal={JOURNAL OF CLIMATE}, author={Michaelis, Allison C. and Willison, Jeff and Lackmann, Gary M. and Robinson, Walter A.}, year={2017}, month={Sep}, pages={6905–6925} }
 @article{michaelis_lackmann_2013, title={Numerical modeling of a historic storm: Simulating the Blizzard of 1888}, volume={40}, ISSN={["1944-8007"]}, DOI={10.1002/grl.50750}, abstractNote={The National Oceanic and Atmospheric Administration/Cooperative Institute for Research in Environmental Sciences Twentieth Century Reanalysis (20CR) is used to explore the feasibility of high‐resolution simulation of a historic extratropical cyclone event: The New England Blizzard of 1888. Using the 20CR as initial and lateral boundary conditions for the Weather Research and Forecasting model, a reasonable depiction of the cyclone is obtained, albeit displaced significantly to the north of the observed cyclone during the later stages of the event. Despite the position error, the simulated storm produces heavy snowfall over parts of New England and intense offshore cyclogenesis.}, number={15}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Michaelis, Allison C. and Lackmann, Gary M.}, year={2013}, month={Aug}, pages={4092–4097} }