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
Received: 16 Jun 2016 – Discussion started: 24 Jun 2016
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.
Revised: 05 Jan 2017 – Accepted: 13 Feb 2017 – Published: 03 Mar 2017
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.