Article

Theoretical and Applied Climatology

, Volume 57, Issue 1, pp 11-33

Climatology of cloud and radiation fields in a numerical weather prediction model

  • R. I. CullatherAffiliated withDepartment of Earth and Atmospheric Sciences, Purdue University
  • , HarshvardhanAffiliated withDepartment of Earth and Atmospheric Sciences, Purdue University
  • , K. A. CampanaAffiliated withNational Centers for Environmental PredictionDepartment of Earth and Atmospheric Sciences, Purdue University

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Summary

Satellite-derived datasets are used to verify the cloud cover and radiation field generated by a T62 (horizontal resolution) version of the operational global model at the National Meteorological Centre (NMC). An ensemble of five day forecasts for July 1985 is used, as well as 30 day climatological forecasts for July 1985, October 1985, January 1986, and April 1986.

Monthly averages of radiation fields are compared with Earth Radiation Budget Experiment (ERBE) data. For the four months examined, clear-sky outgoing longwave radiation (clear-sky OLR) and absorbed shortwave radiation (clear-sky SW) tend to agree roughly with ERBE. Model global mean OLR, however, exceeds that of ERBE by 10 W m−2.

Comparison of effective cloud cover to corresponding fields cataloged by the International Satellite Cloud Climatology Project (ISCCP C1) reveals deficiencies in the amount of supersaturation cloudiness and the vertical distribution of convective clouds. Large inaccuracies in model radiation fields are closely related to deficiencies in the cloud parameterization. An inventory of model cloudiness, in comparison to satellite data, is conducted.