EXTREME TEMPERATURES TRENDS IN EASTERN BULGARIA DURING THE PERIOD 1959-2009
VENETA IVANOVA
ABSTRACT. -
Extreme temperatures trends in eastern Bulgaria during the period 1959-2009. The present study investigates variations of four, so called “Core” extreme temperature indices. For the period of 1959-2009 based on the STARDEX project, data from 16 weather stations located in the eastern Bulgaria were analyzed. The temperature indices include the threshold of 0°C, which is applicable for almost every type of climate: two indices refer to the degree of extrema (txq90-Tmax 90th percentile, tnq10-Tmin 10th percentile) and two - to the frequency (tnfd-Number of frost days Tmin<0°C, txhwd-Heat wave duration). Some statistical parameters for every index were also calculated. For the trends calculation and detection of significance, the Mann-Kendall and Sen’s slope estimator were applied. The spatial distribution of the trends shows similar behavior for the most of stations in every season. The Txq90 series are characterized by statistically significant increasing slopes.Keywords: eastern Bulgaria, extreme temperature index, STARDEX, Mann-Kendall test, Sen’s slope