Analysis of trends in temperature data in arid and semi-arid regions of Iran

摘要

Trend analysis of climatic variables has received a great deal of attention from researchers recently. The main aim of this study was to investigate trends in maximum (T_(max)) and minimum (T_(min)) air temperatures in the annual, seasonal and monthly time-scales for 19 synoptic stations in the arid and semi-arid regions of Iran during 1966-2005. From the results it is clear that the majority of the trends in the annual, seasonal and monthly T_(max) and T_(min) time series showed increasing tendency during the last decades, while the increasing trends in the T_(min) series were stronger than those in the T_(max) series. The trend in annual T_(max) and T_(min) averaged over all 19 stations was 0.090 and 0.444 ℃ per decade, respectively. The Tmax and Tmin warming trends were more obvious in summer and winter than in autumn and spring. On the monthly basis, the highest T_(max)and T_(min) increases of 0.827 and 1.585 ℃ per decade were found at the stations located in the northeastern corner of the region in January and September, respectively.