Influence of bulk microphysics schemes upon Weather Research and Forecasting (WRF) version 3.6.1 nor'easter simulations
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...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/10/1033/2017/gmd-10-1033-2017.pdf |
| Summary: | 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. |
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| ISSN: | 1991-959X 1991-9603 |