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The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model SimulationsCloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distribution parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), groupel and frozen drops/hall] Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bim model explicitly calculates and allows for the examination of both the mass and number concentration of cpecies in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low CCN case produces fever droplets, larger size develop due to greater condencational and collectional growth, leading to a broader size spectrum in comparison to the high CCN case.
Document ID
20040033935
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Tao, Wei-Kuo
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Khain, A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Simpson, S.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Johnson, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Li, X.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Remer, L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: Weather Analysis Forecasting
Location: Taipei
Country: Taiwan, Province of China
Start Date: September 15, 2003
End Date: September 17, 2003
Sponsors: Central Weather Bureau
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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