Inhomogeneity of precipitation and its influencing factors in Northwest China from 1961 to 2015

Inhomogeneous spatiotemporal distribution of precipitation tends to causecauses floods and waterlogging,; an in-depth analysis of the inhomogeneous spatiotemporalthis distribution of precipitation can provide scientific methods for coping with droughts and floods and guiding agricultural production. On the basis ofBased on the monthly precipitation and temperature field data collected by 119 stations in Northwest China from 1961 to 2015, the interannual variability of the precipitation concentration index (PCI) and monthly precipitation accounting for the average proportion of annual precipitation (MPPAP) was detected using the Mann–Kendall test and Sen's slope estimator; further, the degree of importance of the factors that affectaffecting the inhomogeneous distribution of precipitation were analyzed using Random Forestsrandom forests (RF). The resultsResults show that thePCI's spatial distribution of PCI in Northwest China generally decreases and increases in the east and west, respectively; further, the results show that thePCI's interannual variability of PCI significantly fluctuates substantially in southern Xinjiang and the west of the Qinghai Plateau but, and relatively slightly in other areas. As for theRegarding PCI's multi-year average variability of PCI, the annual precipitation distribution tends to be homogeneous in most areas of northwestNorthwest China except in, excluding the middle of the Qinghai Plateau, where the inhomogeneity of annual precipitation distribution intensifies. In terms of the annual precipitation distribution, the monthly precipitation shows an increasing trend in Xinjiang; however, in other regions, it reduces in warm seasons and increases in cold seasons. By contrastContrastingly, MPPAP decreases in warm seasons and increases in cold seasons.ThePrecipitation inhomogeneity of precipitation has a significant negative feedbackresponse to climate warming, i.e., a high annual temperature corresponds to the homogeneity of the annual precipitation distribution in most parts of northwestNorthwest China. The westerly circulation and monsoon are the main factors that affectaffecting the inhomogeneity of precipitation in the northwestern region.