Exploring spatial and temporal trends of diurnal temperature range in the region of the Subarnarekha river basin India

This study analyzed the spatial and temporal trends of diurnal temperature range (DTR) for 35-years (1983-2017) in the region of the Subarnarekha river basin of Jharkhand, India. The daily data of maximum temperature (T-max) and minimum temperature (T-min) were habituated to compute the DTR, whereas rainfall data is used to measure its relationship with DTR, on a monthly annual and seasonal basis. Mann-Kendall test and Sen's slope method has been used to detect the increasing or decreasing trends in climatic data with their statistical significance. The annual mean DTR of the basin is 11.97 degrees C With a maximum in pre-monsoon (16.36 degrees C) and minimum in monsoon (6.94 degrees C). A significant negative trend (- 0.31 degrees C/decade) was observed in annual DTR over the basin. On a seasonal basis, all four seasons show a negative trend in DTR with the largest significant decreasing trend in the pre-monsoon season (- 0.49 degrees C/decade). On an annual and seasonal basis, a significant negative correlation between DTR and rainfall is found, indicating that rainfall has a significant impact on the variation of DTR in this basin. A concomitant increase in rainfall might be one of the possible causes of the decreases in DTR in the basin.