HR: 16:20h
AN: A44B-01 INVITED     [Abstracts]
TI: A Two-moment Stratiform Cloud Microphysics Scheme in the Community Atmosphere Model
AU: * Morrison, H
EM: morrison@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80301, United States
AB: A new stratiform cloud microphysics scheme for the Community Atmosphere Model Version 3 (CAM) General Circulation Model is presented. The goal is to provide a more robust treatment of the moist physics, improve flexibility and self-consistency, and allow for coupling between the cloud microphysics and aerosol. The scheme predicts number concentrations and mixing ratios of cloud droplets and cloud ice, and diagnoses mixing ratios and number concentrations of rain and snow. Droplet activation from aerosol is treated using a diagnosed sub- grid vertical velocity. Global results using the new scheme are compared to the old CAM microphysics scheme as well as observations. The new scheme produces relatively small differences in winds, temperature, and precipitation, but significantly reduces liquid water path in mid-latitude storm tracks and improves the cloud radiative forcing. More detailed tests of the microphysics scheme including sensitivity to vertical resolution and time step are also described.
DE: 3311 Clouds and aerosols
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly