Progress in the study of climatic extremes in northern and central Europe

A study of the long-term changes of various climatic extremes was made join tly by a number of European countries. It was found that the changes in max imum and minimum temperatures follow, in broad terms, the corresponding wel l-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have incre ased. As a result, the study confirms that the diurnal temperature range ha s mostly decreased during the present century in Northern and Central Europ e. Frost has become less frequent. Two extreme-related precipitation charac teristics, the annual maximum daily precipitation and the number of days wi th precipitation greater than or equal to 10 mm, show no major trends or ch anges in their interannual variability. An analysis of return periods indic ated that in the Nordic countries there were high frequencies of 'extraordi nary' 1-day rainfalls both in the 1930s and since the 1980s. There have bee n no long-term changes in the number of high wind speeds in the German Eigh t. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources , a 500-year temperature and precipitation event graph for the Swiss Mittel land is presented. It shows large interdecadal variations as well as the ex ceptionality of the latest decade 1986-1995.