Drought variations are determined by precipitation and temperature changes. The present study examines the relative contributions of precipitation and temperature to temporal variations of short-term, medium-term and long-term droughts over Asia. This is accomplished by comparing (a) the variations of Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) that extend over 3, 9 and 24 months (i.e., short-term, medium-term and long-term droughts, respectively) and (b) the strength of the relationship of SPEI to precipitation and temperature. Both precipitation and temperature contribute to variations of the north–south dipole pattern of short-term and medium-term droughts with a relatively larger contribution from temperature. The contribution of precipitation and temperature to the variations of long-term drought depends upon the spatial pattern. The variation of the north–south dipole pattern of long-term drought is mainly contributed by the temperature trend with additional contribution of precipitation in eastern and southwestern Asia. The variation of the southwest–northeast tripole pattern of long-term drought is mainly contributed by precipitation in central Asia and has a comparable contribution of precipitation and temperature in southern and eastern Asia. The tripole pattern and dipole pattern of long-term drought have a closer relation to the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO), respectively. The PDO effect on long-term drought variation is mainly through modulating precipitation.

AMO,Asian drought variation,different time scales,PDO,precipitation and temperature