Analysis of Spatial and Temporal Variations of Maximum Temperatures in Iran

Maximum temperatures affect a wide range of activities especially in the afternoon hours and warm period of the year. This paper analyses temporal and spatial variations of mean maximum temperatures and the highest temperatures in Iran by using the statistical methods within a 45-year period (1964 to 2008). Temperature zonings were performed by using raster GIS capabilities، and evaluated by various statistical tests. Also the relationships between maximum temperatures and geographical factors، as well as temperature trends، were investigated via regression equations. The results of the study revealed six different zones of maximum temperatures in Iran. Analysis of the maps and comparison of the standardized β coefficients of multivariate regression models، confirms the latitude and then the altitude significant roles in controlling the maximum temperatures، especially during the cold period of the year، along with the lowest temperature variabilities in the southern coasts. Shapiro-Wilk and Levene tests indicated respectively normality of the temperatures and in most cases equality of temperature variances between zones. Also Games-Howell and Gabriel tests proved that the mean maximum temperatures among the zones have significant pairwise differences in all time scales that prove the accuracy of the zonings. Mean afternoon temperature over the country was calculated based on raster calculations at the rate of 25. 3○C، which has been increased at the rate of 0. 62○C compared to the last 45 years.