spatial-temporal analysis of heat waves in iran over the last three decades

the purpose of this research is to analyze heat waves characteristics in the warm period of the year as a climatic hazard in iran. in this study, the daily maximum temperature is taken at 44 synoptic stations during the period 1981-2010. these temperature values were used to extract the intensity, frequency and duration of heat waves using percentile thresholds of 90, 95, and 98. the results showed that the average heat waves intensity is added between 3 to 4°c during summer more than spring. during spring and summer seasons, the most intense of heat waves is occurred on the southern coasts of iran, and the most frequency of heat waves is occurred in the zagros mountains and eastern scattered mountainous of iran. on average, the heat waves frequency is increased about 4 more heat waves during summer than spring. furthermore, the seasonal average of the most duration of heat waves about 10 to 16 consecutive days has occurred in the southeastern of iran. generally, in the higher percentile thresholds heat waves frequency is reduced, but the intensity and duration are increased.