Long-term variations and synoptic features of heat waves in Turkiye

This study investigates the frequency distribution and magnitude changes of heat waves (HWs) together with their controlling synoptic mechanisms for Turkiye. Daily maximum temperature (Tmax) records of 94 meteorological stations are used for the period 1960-2019. Tmax above the 90th percentile and at least three consecutive days are used to define heat wave (TmaxHW) for the warm period (May-September) of a year. Total numbers of HWs are in increasing mode in Turkiye, especially in the last decade. Maximum increase in the number of HWs (NHWs) is shown in the coastal areas (Marmara, Aegean and Black Sea regions with 0.54, 0.46, and 0.44 NHWs/decade, respectively). For Aegean, extension of Asiatic summer monsoon low to the central Anatolia and associated easterly terrestrial surface winds, high temperature gradients at 850-hPa level, extension of mid-level ridge and associated abnormal decreases in cloud cover are the main reasons causing heat wave events.