Parameterization of cloud microphysical processes in the CSU general circulation model
Date
1992-02
Authors
Smith, Laura D., author
Randall, David A., author
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Abstract
The chief microphysical processes required to simulate the formation and dissipation of cloudiness have been implemented in the CSU general circulation model (GCM) with the aim to (1) yield a more physically-based representation of the sources and sinks of the atmospheric moisture components, (2) link the fractional cover and optical properties of model-generated clouds to predicted liquid/ice water amounts; and (3) produce more realistic temporal behaviors of the cloud fields. The bulk microphysics scheme encompasses five prognostic variables of water vapor, cloud water, cloud ice, rain, and snow. Cloud liquid and ice water amounts are predicted to form through large-scale condensation and sublimation processes plus detrainment at the top of convective cumulus towers. The instantaneous production of rain and snow is obtained through autoconversion of liquid water droplets and ice crystals. The growth process of rain drops and snow flakes falling through the free atmosphere is simulated using the continuous collection equation. Evaporation of cloud liquid, cloud ice, rain, and snow occurs in subsaturated layers. Melting and freezing are also taken into account. This document gives a description of the cloud microphysics package and its implementation into the CSU GCM.
Description
February 1992.
Rights Access
Subject
Cloud physics
Atmospheric turbulence
Atmospheric physics