Liquid and ice cloud microphysics in the CSU general circulation model. Part I: Model and description and simulated microphysical processes
- Colorado State Univ., Fort Collins, CO (United States)
Microphysical processes of formation and dissipation of water and ice clouds have been incorporated in a general circulation model to yield a more physically based representation of atmospheric moisture budget components, link distribution and optical properties of modeled clouds to predicted cloud water and ice amounts, and produce more realistic simulations of cloudiness and radiation budget. The bulk cloud microphysics scheme encompasses variables for water vapor mass, cloud water, cloud ice, rain, and snow. Cloud water and cloud ice are predicted to form through large-scale condensation and deposition and through detrainment at the tops of cumulus towers. Two annual-cycle simulations assess the impact of cloud microphysics on the hydrological cycle. In the EAULIQ run, large-scale moist processes and cloud optical properties are driven by bulk cloud microphysics parameterization. In the CONTROL run, condensed water is immediately removed from the atmosphere as rain, which may evaporate as it falls through subsaturated layers. Results are presented for January and July monthly averages. Emphasis is placed on spatial distributions of cloud water, cloud ice, rain, and snow. In EAULIQ, cloud water and cloud ice are more abundant in middle latitudes than in the tropics, suggesting that large-scale condensation contributes a major part to condensed water production. Comparisons between simulated vertically integrated cloud water and columnar cloud water retrievals from satellite measurements indicate reasonable agreement. Interactions between cloud microphysics and cumulus convection parameterizations lead to smaller, more realistic precipitation rates. In particular, the cumulus precipitation rate is strongly reduced when compared to CONTROL. 95 refs., 18 figs., 4 tabs.
- OSTI ID:
- 273947
- Journal Information:
- Journal of Climate, Journal Name: Journal of Climate Journal Issue: 3 Vol. 9; ISSN 0894-8755; ISSN JLCLEL
- Country of Publication:
- United States
- Language:
- English
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