Changes in annual temperature extremes in the Carpathians since AD 1961

The Carpathian Mountains region cover areas from seven countries of central and southeastern Europe, the mountain chain having major regional influences on the temperate climate, specific to latitudes between 43°N and 49°N. In order to identify changes in the annual temperature extremes, the Mann–Kendall nonparametric trend test has been applied to several thermal indices, recommended by the expert team on climate change detection and indices. The indices were computed from gridded daily datasets of minimum and maximum temperature at 0.1° resolution (~10 km), available online within the framework of the project CarpatClim (climate of the Carpathian region) for the period 1961–2010. The results show decreasing trends in cold-related indices, especially in the number of frost days, and increasing trends in warm-related ones. The trend patterns are consistent over the region, i.e., there are no mixed trends for a given index. Regional differences in climate extreme trends within the Carpathian region are related to altitude, rather than latitude. The number of summer days is increasing over the entire area, while the number of tropical nights presents upward trends mainly at lower elevations. The Warm Spell Duration Index presents upward trends over 60 % of the region. The (annual) East Atlantic pattern shows strong correlations with the warm-related indices. Our results are in agreement with previous temperature-related studies in the region.