Trend analysis of surface longwave and shortwave radiation over Europe

The results of a detailed trend analysis of surface longwave and shortwave radiation over Europe are presented on a basis of data from the ISCCP project (International Satellite Climatology Cloud Project). The ISCCP FD SRF dataset includes spatially and temporally homogenized up-welling and down-welling longwave (LW = 5.0-200.0 microns) and shortwave (SW = 0.2-5.0 microns) radiation estimates coming from the synergistic use of satellite data and models. The area of interest, Europe, consists of equal area grids with a spatial resolution of equatorial 2.5x2.5 degrees (280 km²). The temporal resolution of the data is 3 hours while the dataset spans from January 1984 to December 2007. In order to study the long-term variations of the longwave and shortwave radiation, monthly mean values of the above mentioned period were considered. A statistical analysis is applied to derive trends and seasonal variability for this time period over Europe. To fit the time series, a model with a linear trend and a seasonal component for the annual cycle of radiation has been used. The seasonal component is estimated by a harmonic analysis. The significance of the longwave and shortwave radiation trend is also determined. As it is shown here, the observed trends and their significance are rather variable for different areas in Europe.