HR: 0830h
AN: A31E-0087    [PDF]
TI: Improved Precipitation Simulations using Spectral (bin) Microphysics in a Mesoscale Atmospheric Model.
AU: * Lynn, B H
EM: barry@dina.es.huji.ac.il
AF: Hebrew University of Jerusalem, Institute of the Earth Sciences, Givat Ram, 91904 Israel
AU: Khain, A
EM: khain@vms.huji.ac.il
AF: Hebrew University of Jerusalem, Institute of the Earth Sciences, Givat Ram, 91904 Israel
AB: A new, faster, spectral (bin) microphysics model, SBM Fast, has been developed and coupled to the mesoscale model, MM5. The SBM Fast, which is based on the micro-physical package of the Hebrew University, solves a system of equations for size distribution functions for water drops, three types of ice crystals (plates, columns, and dendrites) as well as snowflakes, graupel, and hail/frozen drops. A budget for aerosols is used to obtain the spectrum of condensation nuclei, which is used to obtain the initial drop spectrum. The coupling of SBM Fast to the three-dimensional mesoscale model, MM5, allows SBM Fast to simulate microphysics within a realistic, time-varying mesoscale environment. Thus, the SBM Fast model can be used, potentially, to improve precipitation forecasts during warm rain or mixed convective, and/or cold-season snow events. This work describes results from high resolution simulations of a convective, mesoscale precipitating system that developed over Florida 27th July 1991. The focus is on the evolution of sea-breeze fronts into a convective squall line, that includes stratiform cloud development. Analysis suggests that the MM5 SBM reproduces well cloud structure, cloud type, winds, and precipitation amounts. Results further show the importance of initial aerosol concentration on vertical velocity, cloud structure, and rainfall.
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting