Sensitivity of the thermal balance in a general circulation model to a parameterization for cumulus convection with radiatively interactive clouds

Journal Article · Sat Nov 01 04:00:00 EST 1986 · J. Atmos. Sci.; (United States)

DOI:https://doi.org/10.1175/1520-0469(1986)043<2277:SOTTBI>2.0.CO;2· OSTI ID:5946906

Donner, L J

The dependence of thermal balance of a general circulation model on the parameterization of cumulus convection is investigated. Incorporation of a Kuo-type cumulus parameterization into the NCAR community climate model decreases temperatures in most of the lower and middle tropospheres while increasing temperatures slightly at the tropopause, decreases both relative and specific humidities in large parts of the lower troposphere, and also reduces cloud cover and tropical precipitation. Although the Kuo parameterization represents a vertically integrated heat source, its presence in the general circulation model causes an even larger reduction in heating by the moist adiabatic adjustment, so the total heating associated with cumulus convection is less if the Kuo parameterization is used. The reduction in atmospheric temperatures relative to those at the surface with the Kuo parameterization results in enhanced heating of the lower atmosphere by surface exchange processes. These changes in convective and surface heating dominate changes in the diabatic part of the thermal balance but are moderated by changes in radiative heating associated with reduced cloudiness. Diabatic heating changes are balanced primarily by reduced mean dynamic transport of heat associated with a weakened Hadley circulation. Dependence of the circulation sensitivity to cumulus parameterization of cloud-convection feedback and the penetrative extent of convection is found to be significant. Penetrative depth of convection is especially important; since penetration by convection depends crucially on the poorly understood entrainment process, some uncertainty plagues estimates of the details of the impact of cumulus convection on the simulated general circulation. Changes in cloudiness associated with the Kuo parameterization alter radiative forcing so as to reduce the sensitivity of the community climate model to the cumulus parameterization.

• Research Organization: National Center for Atmospheric Research, Boulder, CO
• OSTI ID: 5946906
• Journal Information: J. Atmos. Sci.; (United States), Journal Name: J. Atmos. Sci.; (United States) Vol. 43:21; ISSN JAHSA
• Country of Publication: United States
• Language: English

Related Subjects

500100* -- Environment
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
CLIMATES
CLOUDS
CONVECTION
ENERGY
ENERGY TRANSFER
GENERAL CIRCULATION MODELS
HEAT
HEAT TRANSFER
HUMIDITY
MASS TRANSFER
MATHEMATICAL MODELS
SENSITIVITY ANALYSIS
TEMPERATURE DEPENDENCE
THERMAL ANALYSIS