Moisture sources of heavy precipitation in Xinjiang characterized by meteorological patterns

Abstract

AbstractIn this study, the FLEXible PARTicle dispersion model (FLEXPART) is applied to determine the moisture source of heavy precipitation in Xinjiang in the wet season (April–September) from 1979 to 2018. This is investigated for different meteorological patterns of heavy precipitation categories based on the self-organizing maps (SOM) method. The SOM results suggest that there are four main meteorological patterns (N1, N2, N3 and N4) for heavy precipitation in Xinjiang. These match the strength and position of geopotential height anomalies at middle-high levels over Central Asia and indicate the anomalous activities of the Central Asia trough and vortex. Further analysis shows that the heavy precipitation is centered at the Tianshan Mountains and the Kunlun Mountains in the N1 and N3 patterns and around the Tianshan Mountains in the N2 and N4 patterns. There are four moisture source regions that contribute to each of the four meteorological patterns for heavy precipitation in Xinjiang, which are listed in descending order of their contribution rates: southern Xinjiang (29–37%), North–Central Asia (19–27%), northern Xinjiang (14–19%), and South–Central Asia (13–16%). The contribution of each source to the heavy precipitation in Xinjiang varies with the meteorological pattern. Additionally, the contribution rates of each source region match well with the precipitation-related particle aggregation before heavy precipitation days. These results help us better understand the moisture source of the heavy precipitation in Xinjiang.