CLARA-A2 stands for "CM SAF cLouds, Albedo RAdiation data record, AVHRR-based, Edition 2" and comprises a suite of radiation and cloud parameters derived within the EUMETSAT Climate Monitoring Satellite Application Facility (CM-SAF) from Advanced Very High Resolution Radiometer (AVHRR) data.
Here we offer (for internal users only) and briefly describe the radiation products. Products are also available for surface albedo and clouds.
Surface incoming shortwave radiation is computed following Müller et al. (2009, see references). Cloud detection & masking is carried out with the AVHRR-PPS package (see Dybbroe et al., 2005 under references of the CLARA-A2 albedo product). Additionally required independent surface albedo and aerosol information is based on climatologies (GADS/OPAC and SARB/CERES), other meteorological information is taken from ERA-Interim reanalysis data. For cloudy grid cells look-up tables are used. The temporal averaging takes into account the diurnal cycle of solar radiation.
The surface outgoing longwave radiation is basically based on respective ERA-Interim data corrected for differences in terrain elevation and spatial resolution.
The surface downwelling longwave radiation is basically as well based on respective ERA-Interim data corrected for terrain elevation and cloud cover effects.
Details about the processing steps can be found in the respective ATBD as well as in the paper of Karlsson et al. (2015) in the references.
We offer edition 2 of the CLARA data set, i.e. CLARA-A2, only for internal use.
The data set was included into the ICDC data base on May 24 2018.