spatial-temporal variations and trends in freezing level height in iran: an analytical perspective

This research investigates the temporal and spatial changes of freezing level height (flh) in iran over the statistical period from 1940 to 2023, using the modified mann-kendall non-parametric analysis method. the results indicate a significant upward trend in flh from december to april. except for summer, the upward trend is quite evident during autumn, winter, and spring. annual changes in flh show a significant upward trend during the study period. these significant upward trends at monthly, seasonal, and annual scale can show one of the consequences of climate change in iran. spatial analysis reveals an inverse relationship with the latitude, and as latitude decreases (towards southern regions of iran), flh increases. this relationship is more clear in winter, with the correlation coefficient between flh and latitude being significant at the 0.05 alpha level. additionally, flh shows a direct relationship with longitude, increasing as one moves eastward. the highest freezing level height is observed in chabahar (4347.5 meters) in southeastern iran. considering the decrease in snow cover and increase in heavy rainfall in iran, monitoring variations in freezing level height can be useful for predicting these variables. this research investigates the temporal and spatial changes of freezing level height (flh) in iran over the statistical period from 1940 to 2023, using the modified mann-kendall non-parametric analysis method. the results indicate a significant upward trend in flh from december to april. except for summer, the upward trend is quite evident during autumn, winter, and spring. annual changes in flh show a significant upward trend during the study period. these significant upward trends at monthly, seasonal, and annual scale can show one of the consequences of climate change in iran. spatial analysis reveals an inverse relationship with the latitude, and as latitude decreases (towards southern regions of iran), flh increases. this relationship is more clear in winter, with the correlation coefficient between flh and latitude being significant at the 0.05 alpha level. additionally, flh shows a direct relationship with longitude, increasing as one moves eastward. the highest freezing level height is observed in chabahar (4347.5 meters) in southeastern iran. considering the decrease in snow cover and increase in heavy rainfall in iran, monitoring variations in freezing level height can be useful for predicting these variables.