Spatio-Temporal Changes in Annual Temperature Extremes over Romania (1961-2013)

摘要

In order to identify changes in the annual temperature extremes, the Mann-Kendall non-parametric trend test has been applied to several thermal indices, recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The indices were computed from gridded daily data of minimum and maximum temperature at 0.1° resolution (~10 km), freely available within the ROCADA dataset for the period 1961–2013. The results show decreasing trends in cold-related indices, especially in the number of frost days, and increasing trends in warm-related extremes. The trend patterns are consistent over the region, i.e., there are no mixed trends for a given index. The regional differences in climatic trends over Romania are related to altitude, rather than latitude. The key findings suggest a country-wide increasing frequency of summer days, an increase of tropical nights frequency at lower elevations, a reduction of frost season and a widening of the growing season in the extra-Carpathian regions. The duration of warm spells have been increasing over most of Romania. Our results are in agreement with previous temperature-related studies in the region.