A51D-0093
Investigation on Different Parameterizations of Cloud Droplet Spectral Dispersion on Simulated Precipitation and Radiation in NCAR CAM5
Friday, 18 December 2015
Poster Hall (Moscone South)
Minqi Wang1, Yiran Peng1, Yanluan Lin2, Bin Wang3, Yu Liu4 and Yangang Liu5, (1)Center for Earth System Science, Tsinghua University, Beijing, China, (2)Tsinghua Univ, Beijing, China, (3)IAP Insititute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, (4)CAMS Chinese Academy of Meteorological Sciences, Beijing, China, (5)Brookhaven Natl Lab, Upton, NY, United States
Abstract:
Relative dispersion (the ratio of standard deviation to the mean radius) of cloud droplet size distribution can substantially affect the calculation of effective radius in atmospheric general circulation models (GCMs). Overestimate of the first aerosol indirect effect in current GCM is partly related to the uncertainties associated with the cloud spectral dispersion. Empirical, semi-empirical and analytical expressions of spectral shape parameters are examined within the cloud microphysical scheme in NCAR CAM5 (Community Atmosphere Model, version 5.0). Simulated values of cloud effective radius are compared with MODIS and CERES retrievals in low level clouds to verify the dispersion parameterizations. As a result, the first aerosol indirect effect is globally reduced by 15% with the empirical method but enhanced by 9% with the analytical method. Impacts of different dispersion parameterizations on model simulated cloud, radiation and precipitation characteristics are also evaluated against various observations.
