Diurnal temperature range over Europe between 1950 and 2005

It has been widely accepted that diurnal temperature range (DTR) decreased on a global scale for the second half of the twentieth century. In contrast, we show that the long-term trend has reversed from decrease to increase during the 1970s in Western Europe and during the 1980s in Eastern Europe. The analysis is based on the high- quality dataset of the European Climate Assessment and Dataset Project, from which we selected about 200 stations, covering the area from Iceland to Algeria and from Turkey to the European part of Russia for 1950 to 2005. We investigate national and regional means as well as the pan-European mean with respect to trends and reversal periods. 17 of the 24 investigated regions including the pan-European mean show a significant increase since 1990 at the latest. Of the remaining 7 regions, 2 show a non-significant increase, 3 a significant decrease and the remaining 2 no significant trend. The long-term change in DTR is considered to depend on both, incoming shortwave radiation and outgoing long-wave radiation, the former of which has undergone a change from dimming to brightening. Consequently we discuss the connections between DTR, shortwave radiation and sulfur emissions which are thought to be amongst the most important factors influencing the incoming solar radiation through the primary and secondary aerosol effect. We find reasonable agreement between trends in SO2 emissions, radiation and DTR in areas affected by high pollution. Consequently we conclude that the long- term trends in DTR are mostly determined by emissions and the incoming solar radiation.