Spatio-temporal changes of heat and cold wave patterns in western Iran

ABSTRACT: In this study, we investigated recent changes in frequency, intensity, and duration of heat waves and cold waves in western Iran, a semi-arid region where agricultural activities represent the major contribution to the region’s economy. Our results show that heat waves have become significantly more frequent, longer, and more intense since the end of the 20th century, while cold waves have behaved in the inverse way. Through a detailed synoptic analysis, we found that the action centers derived from the expansion of the Azores high pressure over the Arabian Desert and the Iranian plateau were mainly responsible for all heat waves. However, cold waves responded to 4 different patterns, of which the Siberian high pressure was the main atmospheric configuration leading to the most intense and persistent events.