Spatial analysis of dew point temperature trend changes in Iran

Dew point temperature is one of the most important atmospheric variables and its long-term changes can lead to changes in the climatic characteristics of an area. In order to spatially analyze the trend of dew point temperature changes in Iran, the annual and monthly average data of this variable in 109 synoptic meteorological stations during the statistical period of 1990-2022 have been used. In order to investigate the effect of changes in other atmospheric variables on dew point temperature, the data of average annual relative humidity, average minimum and average maximum temperature, and average total annual precipitation have been used. In order to investigate the change process using the Mann-Kendall method and to identify the patterns governing the spatial changes of the dew point temperature in Iran, the spatial autocorrelation models of Global Moran and Getis-Ord General G statistic have been used. The results of investigating the trend of dew point temperature changes show that this variable has an increasing trend in the areas around the north and South Seas and the northwest region, and a decreasing trend in the central, eastern and northeastern regions of Iran. Spatial analysis of areas with high dew point temperature shows a severe cluster pattern, which means that areas with high dew point temperature are mainly spread in parts of the coasts of the Caspian Sea and many parts of the coasts of the Persian Gulf and Oman Sea, parts of northern Azerbaijan and Ardabil. This shows that the temperature of the dew point increases as it approaches moisture sources. Also, the spatial analysis of the areas with low dew point temperature also shows that these types of temperatures are generally concentrated in a large part of the central areas of the south of Khorasan province and the east and southeast of Iran.