Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 10, 1033-1049, 2017
http://www.geosci-model-dev.net/10/1033/2017/
doi:10.5194/gmd-10-1033-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Model evaluation paper
03 Mar 2017
Influence of bulk microphysics schemes upon Weather Research and Forecasting (WRF) version 3.6.1 nor'easter simulations
Stephen D. Nicholls1,2, Steven G. Decker3, Wei-Kuo Tao1, Stephen E. Lang1,4, Jainn J. Shi1,5, and Karen I. Mohr1 1NASA-Goddard Space Flight Center, Greenbelt, MD 20716, USA
2Joint Center for Earth Systems Technology, University of Maryland, Baltimore, MD 21250, USA
3Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08850, USA
4Science Systems and Applications, Inc., Lanham, MD 20706, USA
5Goddard Earth Sciences Technology and Research, Morgan State University, Baltimore, MD 21251, USA
Abstract. This study evaluated the impact of five single- or double-moment bulk microphysics schemes (BMPSs) on Weather Research and Forecasting model (WRF) simulations of seven intense wintertime cyclones impacting the mid-Atlantic United States; 5-day long WRF simulations were initialized roughly 24 h prior to the onset of coastal cyclogenesis off the North Carolina coastline. In all, 35 model simulations (five BMPSs and seven cases) were run and their associated microphysics-related storm properties (hydrometer mixing ratios, precipitation, and radar reflectivity) were evaluated against model analysis and available gridded radar and ground-based precipitation products. Inter-BMPS comparisons of column-integrated mixing ratios and mixing ratio profiles reveal little variability in non-frozen hydrometeor species due to their shared programming heritage, yet their assumptions concerning snow and graupel intercepts, ice supersaturation, snow and graupel density maps, and terminal velocities led to considerable variability in both simulated frozen hydrometeor species and radar reflectivity. WRF-simulated precipitation fields exhibit minor spatiotemporal variability amongst BMPSs, yet their spatial extent is largely conserved. Compared to ground-based precipitation data, WRF simulations demonstrate low-to-moderate (0.217–0.414) threat scores and a rainfall distribution shifted toward higher values. Finally, an analysis of WRF and gridded radar reflectivity data via contoured frequency with altitude diagrams (CFADs) reveals notable variability amongst BMPSs, where better performing schemes favored lower graupel mixing ratios and better underlying aggregation assumptions.

Citation: Nicholls, S. D., Decker, S. G., Tao, W.-K., Lang, S. E., Shi, J. J., and Mohr, K. I.: Influence of bulk microphysics schemes upon Weather Research and Forecasting (WRF) version 3.6.1 nor'easter simulations, Geosci. Model Dev., 10, 1033-1049, doi:10.5194/gmd-10-1033-2017, 2017.
Publications Copernicus
Download
Short summary
This study evaluated the impact of five hydrometeor species physics schemes during seven intense winter storm events in the northeastern United States. Model simulations were evaluated against gridded analysis data, precipitation, and weather radar derived products. Results show minor differences in simulated precipitation and large-scale regional patterns, yet simulated weather radar fields were more accurate in physics schemes with less ice pellet content above the melting layer.
This study evaluated the impact of five hydrometeor species physics schemes during seven intense...
Share