Detection of climate change using air temperature series in the west of Iran

In this research، in order to investigate climate change occurrence in west of Iran، 46 years observed data (1961-2006) of 17 synoptic stations of the area were used and evaluated. To this regard، significant variations values of maximum، minimum and average air temperatures as well as diurnal temperature range (DTR) on both annual and seasonal time series were analyzed on two steps. First، the data period was considered as three categories including: 46، 30 and 16 years، and the normal climate duration base variation temperature was identified on the all of stations. Then، significant variations were identified based on the averages values comparison، using the Mann-Whitney and t-Test methods. Data trend was evaluated from the 16 years period which was concern to recent period and has significant variations (at 95% level) comparing the other durations. Base on trend analysis results، Values of maximum، minimum and average air temperatures showed increasing and DTR decreasing variations. The maximum and minimum differences were related to minimum and maximum air temperatures، respectively. Regional investigation of results، illustrated that the most important variations were concerned to semi arid climate (Saghaz، Shahr-kord، Kermanshah and Tabriz stations). Seasonally، winter had also the most important variations. The difference between the 16 years duration and the 30 as well as 45 years durations were 85 and 60%، respectively. During the 16 years period، maximum and minimum stations which had significant trends were observed in summer and fall، respectively.