Simulation of satellite channel radiances in the Met Office Unified Model

A system is described which allows satellite channel radiances to be simulated within both the numerical weather prediction and climate versions of the Met Office Unified Model. It is based on a spherical harmonics version of the radiation code that calculates radiative fluxes and heating rates in the climate model and it uses the same pre‐processing software and molecular absorption database. In the results shown here, fractional cloud cover is represented by decomposition into separate columns. The methodology is described and results of off‐line tests of the code against high spectral resolution calculations are presented. Examples of infrared window and water vapour channel brightness temperatures simulated using the global forecast model are then compared with Meteosat 7 imagery. The utility of radiance simulations for model validation studies is illustrated by these comparisons, and other applications are also discussed. © Crown copyright, 2003. Royal Meteorological Society

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