The SARAH-2 data set comprises five parameters related to the surface solar irradiance, four of which we offer here for internal use: cloud effective albedo (CAL), surface incoming shortwave radiation (SIS), surface incoming direct shortwave radiation (SID), and surface direct normalized shortwave radiation (DNI). All these are derived from observations of the geostationary first generation (Meteosat-MVIRI) and second generation (Meteosat-SEVIRI) satellite sensors. The data set therefore basically covers Africa, Europe, and most of the Atlantic Ocean.
This EUMETSAT CM-SAF data product is based on a combination of the Heliosat approach to obtain the effective cloud albedo from raw data obtained by the MVIRI and SEVIRI sensors (Hammer et al., 2003) with a radiative transfer model specifically designed for clear sky conditions (MAGIC, Mueller et al., 2009, Mueller et al., 2015). The Heliosat approach is merely based on MVIRI data while the radiative transfer model MAGIC and the final irradiance retrieval requires a number of additional parameters: atmospheric total water vapor content (ERA-Interim and ERA40), a monthly ozone climatology, the surface albedo (SARB/CERES) and a monthly aerosol climatology. Together the approach is referred to as MAGICSOL (see Posselt et al., 2012, 2014). More information is given in the Product User Manual (PUM) and in the Algorithm Theoretical Basis Document (ATBD).
The Eumetsat CM-SAF SARAH ed. 2 product offered here comes at monthly temporal resolution; daily data can be provided upon request for internal users.
Last update of the data set at ICDC: April 26 2018.