Abstract: Supported by temperature and precipitation observations from 54 groundbased stations in the Indus River Basin and surrounding areas, we used Climate Research Unit temperature and Global Precipitation Climatology Centre precipitation global land surface reanalysis datasets to construct a new gridded monthly dataset covering the entire Indus River Basin.This dataset achieved a spatial resolution of 0.5°×0.5° for 1980-2016.We derived potential evapotranspiration values with the Thornthwaite model in order to further analyze the drought characteristics in the basin according to the Standard Precipitation Evapotranspiration Index.Our results revealed that the areal averaged annual mean temperatures increased significantly between 1980 and 2016, with a rate of 0.30 ℃ ·(10 a)^-1.The most obvious increase occurred in the early 21st century.On a seasonal timescale, the observed increase was much faster in the dry season (NovemberApril; 0.36 ℃ ·(10 a)^-1) than it was in the wet season (MayOctober; 0.25 ℃ ·(10 a)^-1).Unlike the monotonic increase observed for temperature, annual precipitation revealed a decadal oscillation.Driven by the persistent warming, annual and seasonal potential evapotranspiration rates have increased significantly.We also detected that drought frequency showed decadal fluctuations similar to those of precipitation patterns.Drought was more common in the dry season, but drought intensity is higher in the wet season.Meanwhile, the extent of drought-stricken areas experienced a weak increasing trend in the dry season, but a slight decrease in the wet season.Spatially, the 1980-2016 increases in seasonal and annual temperature and potential evapotranspiration were significant at a 95% confidence level throughout the Indus River Basin, except for a small fraction in the northwestern portion of the region.Warming was sharpest in the southern plain and the northeastern mountain regions, while potential evapotranspiration rose particularly quickly in the southern plain.Over the same period, annual and wetseason precipitation along the southeast-to-orthwest belt from New Delhi to Kabul increased significantly, as did dry-season precipitation around Kabul.We detected a significant drying trend during the dry season for the southeastern plain and for some parts of the northeastern mountain region.When combined with the drying that we saw during the wet season for the northeastern and southwestern mountain regions, our results signal the importance of strengthening our preparation for climate-related disaster prevention.Effective countermeasures need to be identified and implemented in order to mitigate the adverse effects of continued drought intensification.

Key words: temperature, precipitation, evapotranspiration, drought, spatiotemporal variations, Indus River Basin