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The impact of size distribution assumptions in a bulk one-moment microphysics scheme on simulated surface precipitation and storm dynamics during a low-topped supercell case in Belgium

Journal Article · · Monthly Weather Review
In this research the impact of modifying the size distribution assumptions of the precipitating hydrometeors in a bulk one-moment microphysics scheme on simulated surface precipitation and storm dynamics has been explored for long-lived low-topped supercells in Belgium. It was shown that weighting the largest precipitating ice species of the microphysics scheme to small graupel results in an increase of surface precipitation because of counteracting effects. On the one hand, the precipitation formation process slowed down, resulting in lower precipitation efficiency. On the other hand, latent heat release associated with freezing favored more intense storms. In contrast to previous studies finding decreased surface precipitation when graupel was present in the microphysics parameterization, storms were rather shallow in the authors simulations. This left little time for graupel sublimation. The impact of size distribution assumptions of snow was found to be small, but more realistic size distribution assumptions of rain led to the strongest effect on surface precipitation. Cold pools shrunk because of weaker rain evaporation at the cold pool boundaries, leading to a decreased surface rain area.
Research Organization:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Organization:
DOE - OFFICE OF SCIENCE
DOE Contract Number:
AC02-98CH10886
OSTI ID:
1019513
Report Number(s):
BNL--95262-2011-JA; KP1701000
Journal Information:
Monthly Weather Review, Journal Name: Monthly Weather Review Journal Issue: 4 Vol. 139; ISSN MWREAB; ISSN 0027-0644
Country of Publication:
United States
Language:
English