The Spatio-Temporal Variability of Extreme Temperature Using Gridded AgMERRA Dataset over the Bakhtegan-Maharloo Basin, Iran

Trend analysis of climatic variables has got a great deal of notice from researchers recently. This study aimed to investigate the Spatio-temporal variability of extreme temperature indices based on the station data and gridded dataset analyses over the Bakhtegan-Maharloo basin in Iran from 1980 to 2010.

Climatic data related to the Bakhtegan-Maharloo basin was extracted from AgMERRA dataset for the study period (1980-2010) using R software. Daily temperature data were also extracted from the Meteorological Archive of meteorological stations located in the basin during the study period. Warm nights (TN90p), maximum monthly value of daily minimum temperature (TNx), cold nights (TN10p), and cold spell duration indicator (CSDI) indices had been chosen from the indices recommended by the Expert Team for Climate Change Detection Monitoring and Indices (ETCCDMI) and calculated by RClimDex software package.

The results of AgMERRA and stations data revealed an increasing trend in warm extremes including TN90p and TNx with the trend changes ranging from 0.135 to 0.721 and 0.061 to 0.139, respectively, but a declining trend in cold extremes including TN10p and CSDI with the trend changes ranging from -0.517 to -0.125 and -0.987 to -0.167, respectively.

The results of this study may contribute to a better understanding of regional temperature behavior in the study area. The results indicated that the frequency and intensity of cold extremes have declined, though warm extremes increased. Due to the intensive impacts of temperature extremes on human life, it is essential to speculate the effects of these extreme climatic events in future plannings in various sections.