Trends in downward surface solar radiation from satellites and ground observations over Europe during 1983-2010

Trends of all-sky downward surface solar radiation (SSR) from satellite-derived data over Europe (1983-2010) are first presented. The results show a widespread (i.e., non-local dimension) increase in the major part of Europe, especially since the mid-1990s in the central and northern areas and in springtime. There is a mean increase of SSR of at least 2 W m− 2 per decade from 1983 to 2010 over the whole Europe, which, taking into account that the satellite-derived product lacks of aerosol variations, can be mostly related to a decrease in the cloud radiative effects over Europe. Secondly, residual series have been derived as the result of the difference between ground-based and satellite-derived all-sky SSR data. The residual mean series points to a significant increase during the period 1983-2010, with higher rates of around 2 W m− 2 per decade over central and eastern Europe. The spatial variation of these residual time series, which are in line with clear-sky SSR trends over Europe reported in the literature, seem to suggest that these differences in the residual series are not just explained by calibration issues in the satellite-derived product.