Weather and climate are closely related to the radiation budget at the surface. A consortium of six European meteorological services and EUMETSAT have established the Climate Monitoring Satellite Application Facilities CM-SAF to develop and generate data sets for several key climate parameters, based on satellite data. The geophysical products range from data sets for radiation budgets at the surface and at the top of the atmosphere and include cloud properties, water vapor content and profiles as well as temperature profiles. For this, CM-SAF is using mainly the METEOSAT Second Generation satellites; to gain coverage for higher latitudes, NOAA and METOP satellite instruments are used. The surface radiation budget data sets include surface incoming shortwave radiation (SIS), surface albedo (SAL), surface downward longwave (SDL) and outgoing longwave radiation (SOL). The incoming solar radiation is computed by use of SEVIRI and GERB (broadband radiometer) measurements. For surface longwave radiation components, additional input from numerical weather prediction models (temperature and humidity profiles) is used. The outgoing longwave flux product is so far purely model-based because the surface temperature of the NWP model is used as input. The surface net shortwave radiation (SNS) is computed from the SIS and SAL, and the net longwave flux is computed from the SDL and SOL components. Currently the CM-SAF uses the German Weather Service NWP model GME.

The derived CM-SAF data sets include daily and monthly-mean values of these surface fluxes at a resolution of 15 x 15 kmē. Besides the global coverage of the water vapor products, all other products are provided so far on a regional basis covering Europe and parts of Africa. Since 2007 the full disk of MSG is provided, giving full coverage of Africa. This paper presents a study of the annual cycle of surface radiation budget parameters over Europe using these monthly-mean values.

A principal component analysis is used whereby for each parameter of the surface radiation budget the annual cycle is resolved into a set of cycles in time, each with a map describing the associated geographic distribution of that parameter. The first principal component is an annual cycle, and the second is a semi-annual cycle. Both of these components increase with latitude.