Assessing the quality of gridded Climate Data Records of the Surface Irradiance using global Reference Data Sets

The incoming surface solar radiation is an essential climate variable as defined by GCOS. Long term monitoring of this part of the earth’s energy budget is required to gain insights on the state and variability of the climate system. In addition, climate data sets of surface solar radiation have received increased attention over the recent years as an important source of information for solar energy assessments, for crop modeling, and for the validation of climate and weather models.

Gridded regional and global data records of the surface irradiance are available based on satellite measurements as well as derived from numerical models, e.g., reanalysis systems. For climatological analyses, long-term data records, covering about multiple decades, are required. Recently generated satellite-based climate data records from the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF), i.e., SARAH-3 and CLARA-A3, as well as the GEWEX SRB data set, fulfill this requirement. Corresponding reanalysis data are also available, i.e., ERA-5, MERRA-2.

Here we will assess the quality of these satellite-based and reanalysis-derived climate data records of the surface irradiance by comparison with monthly surface reference data from the Global Energy Balance Archive (GEBA). The quality assessment will include the accuracy of the gridded data as well as their ability to realistically reproduce the anomalies and temporal trends as derived from the surface observations. The inter-comparison of the gridded data records allows to identify regions of high / low confidence in our knowledge of the surface irradiance and the surface radiation budget.