Spatiotemporal variability of the precipitation concentration and diversity in Central Asia

Abstract

More extreme precipitation is expected to occur in the arid and wet regions due to climate warming. This intensification will increase the risk of floods, soil erosion, and droughts in the world's dry regions. Exploring the precipitation's irregularity and the daily precipitation concentration in Central Asia (CA) has significant implications for regional agricultural development and ecosystem services. However, the irregularity of precipitation was poorly understood throughout the entire CA due to the sparse meteorological observations. Using the daily Multi-Source Weighted-Ensemble Precipitation (MSWEP-V2.2) from 1979 to 2016 across CA, this study investigated the spatiotemporal variations of the daily precipitation concentration index (CI) and the precipitation diversity and analyzed their attributes and implications. The results demonstrated that the CI was significantly negatively correlated with the precipitation frequency and amount. The distribution of the precipitation frequency diversity (Hfre) and the precipitation amount diversity (Hamount) showed an opposite pattern with the CI, implying that the low Hfre and Hamount values were corresponding to a high precipitation concentration. The high CI values were found in the Tarim Basin and near the Aral Sea, revealing a strong irregularity in precipitation. The decrease regarding the light precipitation frequency or increase in the torrential precipitation frequency generated the increasing precipitation frequency diversity, corresponding to a widespread significant reduction of the CI in CA. The decreased CI and increased precipitation diversity over past decades were likely related to the warming phase of the Atlantic Multidecadal Oscillation. The shift from light to extreme precipitation will trigger the risk of flooding and soil erosion and bring about big challenges for water resources management in the arid and semi-arid regions.