Impact of changes to the radiation transfer parameterizations plus cloud optical properties in the ECMWF model

Abstract

A new radiation package, shown to correct most of the systematic errors of the operational ECMWF radiation scheme, has been extensively tested in the ECMWF forecast model. Improvements in the clear-sky fluxes and radiative heating/cooling rate profiles mainly stem from a better representation of the transmission functions. New cloud optical properties have been set from detailed narrowband calculations for a more realistic model cloud. The radiation budget at the top of the atmosphere is now in good agreement with satellite observations. Several other systematic errors of the ECMWF model are also partially corrected. -from Author