This paper evaluates the solar radiation incident at the Earth’s surface (Rs) for six global reanalyses (NCEP–NCAR, NCEP-DOE; CFSR; ERA-Interim; MERRA; and JRA-55) using surface measurements from different observation networks (GEBA; BSRN; GC-NET; Buoy; and CMA) and the Earth’s Radiant Energy System (CERES) EBAF product from 2001 to 2009. For surface measurements which have instantaneous values of Rs, the daily integrated Rs was obtained from the instantaneous values through a sinusoidal interpolation method.
All selected reanalysis Rs products overestimated monthly Rs when compared to the surface measurements from the five networks. Most reanalysis products showed better accuracy in DJF than that in JJA. Reanalysis was also compared to CERES-EBAF. Almost all of the reanalysis overestimated the monthly Rs over land, the oceans, and the globe. Bias and RMSE values of global reanalyses compared with CERES-EBAF Rs data were smaller than those between the global reanalyses and surface observations.
We could look at using GEBA and CERES for evaluation of MERRA2 and ERA-Interim and compare the results here. These might be sources of solar radiation data for the UK (if we expand our research area).