Improvement of ERA5 over ERA-Interim in Simulating Surface Incident Solar Radiation throughout China

Abstract Surface incident solar radiation ( R s ) is important for providing essential information on climate change. Existing studies have shown that the values from current reanalyses are significantly overestimated throughout China. The European Centre Medium-Range Weather Forecasts (ECMWF) recently released fifth generation of atmospheric reanalysis (i.e., ERA5) with a much higher spatiotemporal resolution and major upgrade compared to its predecessor, ERA-Interim. This study verify whether ERA5 can improve simulation using sunshine duration–derived at ~2200 stations over China 1979 2014 as reference data. Compared observed multiyear national mean, overestimation reduced 15.88 W m ?2 in ERA-Interim 10.07 ERA5. From 1993, (?1.99 decade ?1 ; p < 0.05) (?2.42 estimates continued decrease decline latter closer observed. After they both show strong brightening 2.26 1.49 but observations nonsignificant increase by 0.30 . Due improvement total cloud cover (TCC) ERA5, trend bias induced TCC smaller than In addition, reason why remains biased might be still ignores aerosol changes interannual or decadal time scales. Therefore, subsequent products need their clouds, water vapor, aerosol, especially direct indirect effects