This data set is only available for a restricted user group, please contact us if you want to access these data.
RESTRICTED only accessible in CEN/MPI net or via CliSAP login What does that mean?
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.
|Surface incoming solar radiation (SIS)||W/m²||SIS = (1 - CAL) * SIS_clear-sky|
|as above but for "blue sky" (model result)||W/m²||SIS_clear-sky|
|Surface incoming direct solar radiation (SID)||W/m²||relative to a horizontal plane, wavelengths: 0.2 - 4.0 µm|
|as above but for "blue sky" (model result)||W/m²||SID_clear-sky|
|Surface incoming direct normalized solar irradiance (DNI)||W/m²||normalized with respect to sun zenith angle (SZA)|
|as above but for "blue sky" (model result)||W/m²||DNI_clear-sky|
|Effective cloud albedo (CAL)||none|
Period and temporal resolution:
- 1983-01 to 2015-12
Daily data of the same period are available on request for internal users.
Coverage and spatial resolution:
- Meteosat Disc Area (see Figure above)
- Spatial resolution: 0.05° x 0.05°, geographic grid
- Geographic longitude: about -65°E to 65°E
- Geographic latitude: about -65°N to 65°N
- Dimension: 2601 columns x 2601 rows
- Altitude: following terrain
This data set does not contain separate uncertainty information. The approach has been validated with observations carried out at station of the Baseline Surface Radiation Network (BSRN). BSRN stations used for the validation have been selected carefully. These cover different altitudes and climate zones and have observed solar irradiance for at least one complete annual cycle overlapping the MVIRI time series.
About 95% (almost 85%) of the monthly mean absolute difference values of SIS and SID (DNI) are within the target / threshold values. The mean absolute differences of the monthly mean SIS and SID are well below the target values: 5.1 W/m² and 7.8 W/m² while for DNI these are close to the target value: 16.4 W/m².
Details about the validation and evaluation are given in the CM-SAF Validation Report as well as in the papers by Posselt et al. (2012 and 2014), Mueller et al., (2015), and Pfeifroth et al. (2018) (see references).
ICDC / CEN / University of Hamburg
email: stefan.kern (at) uni-hamburg.de
- Algorithm Theoretical Basis Document (ATBD)
- Product User Manual (PUM)
- Validation Report
- Hammer, A., et al. (2003), Solar energy assessment using remote sensing technologies, Remote Sensing of Environment, 86, 423-432.
- Mueller, R., et al., (2009), The CM-SAF operational scheme for the satellite based retrieval of solar surface irradiance - A LUT based eigenvector hybrid approach, Remote Sensing of Environment, 113, 1012-1024, doi://10.1016/j.rse.2009.01.012.
- Posselt, R., et al., (2012), Remote sensing of solar surface radiation for climate monitoring - The CM-SAF retrieval in international comparison, Remote Sensing of Environment, 118, 186-198, doi:10.1016/j.rse.2011.11.01.
- Posselt, R., et al., (2014), A surface radiation climatology across two Meteosat satellite generations, Remote Sensing of Environment, 142, 103-110, doi:10.1016/j.rse.2013.11.007.
- Müller, R., et al., (2015), Digging the METEOSAT Treasure-3 Decades of Solar Surface Radiation, Remote Sensing, 7(6), 8067-8101, doi:10.3390/rs70608067.
- Pfeifroth, U., et al., (2018), Trends and variability of surface solar radiation in Europe based on surface- and satellite-based data records, J. Geophys. Res.-Atmospheres, 123, 1735-1754, doi:10.1002/2017JD027418.
Please cite the data set as follows:
Pfeifroth, U., Kothe, S., Müller, R., Trentmann, J., Hollmann, R., Fuchs, P., and Werscheck, M., (2017): Surface Radiation Data Set - Heliosat (SARAH) - Edition 2, Satellite Application Facility on Climate Monitoring, DOI:10.5676/EUM_SAF_CM/SARAH/V002, https://doi.org/10.5676/EUM_SAF_CM/SARAH/V002.