Trends of Shortwave and Longwave Surface Radiation in Europe: Spatiotemporal Analysis and Comparison of Satellite and Ground-Based Observations
A detailed investigation of the shortwave (SW) and longwave (LW) up-welling and down-welling surface radiation trends over Europe is presented here. For the purposes of this work, satellite observations from the International Satellite Cloud Climatology Project (ISCCP) for the period 1984–2009 have been spatiotemporally analyzed at a ~280 × 280 km2 resolution. A Fourier-based harmonic analysis technique has been used for the calculation of the trend also allowing for the assessment of its statistical significance. The results are compared to trends calculated from ground-based observations from several World Radiation Data Center (WRDC) stations. The stations have been categorized taking into account their position and the special characteristics of the surrounding region (rural/urban, high/low elevation, population, etc.). The variability of the SW and LW radiation within selected ISCCP grid cells is investigated with the use of ground-based observations. Observed trends and their significance depends on the area of study. Estimated trend for SW radiation over Europe as derived from ISCCP data for the period 1984–2009 is about −0.6 W/m2 and for LW radiation is about 2.47 W/m2.