CLIMATOLOGY OF CLOUD AND RADIATION-FIELDS IN A NUMERICAL WEATHER PREDICTION MODEL

Satellite-derived datasets are used to verify the cloud cover and radi ation 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 198 6, and April 1986. Monthly averages of radiation fields are compared w ith Earth Radiation Budget Experiment (ERBE) data. For the four months examined, clear-sky outgoing longwave radiation (clear-sky OLR) and a bsorbed 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 catalo ged 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 clo ud parameterization. An inventory of model cloudiness, in comparison t o satellite data, is conducted.