Effects of observationally validated cloud-radiation schemes in a general circulation model
- Univ. of California, La Jolla, CA (United States)
This paper very briefly describes an investigation of the effects on climate sensitivity of several different cloud-radiation parameterizations and validations of the parameters with observations. A general circulation model developed from the National Center for Atmospheric Research Community Climate Models (CCM2 and CCM3) was used for the study. In addition to a relative humidity based scheme, four parameterizations incorporating prognostic cloud water were tested, both with and without interactive cloud radiative properties. The globally averaged net cloud forcing was negative in all model versions. The effects of interactive cloud-radiative properties on global climate sensitivity were highly significant. The net cloud-radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and those with specified properties. The increase in cloud water content in a warmer climate leads to optically thicker middle and low clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount produces a positive shortwave feedback for the schemes with specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. Comparisons with measurements suggest that schemes with explicit cloud water budgets and interactive radiative properties are potentially capable of matching observational data closely. 3 refs.
- DOE Contract Number:
- FG03-90ER61061
- OSTI ID:
- 535490
- Report Number(s):
- CONF-970207-; CNN: Grant NAG5-2238; TRN: 97:005076-0022
- Resource Relation:
- Conference: 77. annual meeting of the American Meteorological Society, Long Beach, CA (United States), 2-7 Feb 1997; Other Information: PBD: 1997; Related Information: Is Part Of Eighth symposium on global change studies; PB: 402 p.
- Country of Publication:
- United States
- Language:
- English
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