基于CRA资料的新疆南部暖季大尺度降水和对流性降水特征 postprint

Abstract: Clarifying the structure of precipitation types and their variation characteristics in southern Xinjiang, a typical arid region, is critical for understanding the evolution of the regional water cycle. Based on the China’s First Generation Global Atmospheric Reanalysis from May to September (warm seasons) during 1981-2024, this study used various methods, including trend analysis, wavelet analysis, and Mann-Kendall test, to analyze the characteristics and variation trends of large-scale precipitation (LSP) and convective precipitation (CP) in southern.Xinjiang during warm seasons and their contributions to total precipitation (TP). The results demonstrate that (1) the TP in the mountainous areas of southern Xinjiang is significantly higher than that in the plain areas. TP in mountainous areas of southern Xinjiang is significantly higher than that in plains. LSP is the main source of TP in mountainous areas, where high LSP proportion regions are distributed. CP is the dominant source of TP in plains,which are also high-value areas of CP proportion. Over the past 44 years, TP in southern Xinjiang has shown an overall increasing trend, with a more significant growth trend in mountainous areas than in plains. The growth rate of LSP is obviously higher than that of CP in mountainous areas, while the opposite was true in plains. All three types of precipitation in the mountainous and plain areas changed abruptly around 2000. After 2005, they exhibited a shift from below-normal to above-normal. (2) During each warm season month, the maximum values of mean TP, coefficient of variation, and increasing trend in mountainous and plain areas appear in August and June, respectively. The monthly variation trends of TP are consistent with those of LSP in mountainous areas and with CP in plains, respectively.The mean values and growth trends of TP and LSP are significantly higher in the mountainous areas than in the plain areas. The diurnal variation characteristics of TP in the mountainous areas are dominated by LSP, with distinct differences in the peak periods of the three precipitation types. The TP peak occurs from 14:00 to 23:00 during May-July and delays to 17:00 to 02:00 in August-September; the peak periods of LSP and CP occur around 20:00 and 14:00, respectively. In the plain areas, the peak times of the diurnal variations of the three precipitation types are comparable, all occurring from 20:00 to 02:00, and the diurnal variation of TP is jointly influenced by LSP and CP. (3) Over the past 44 years, the TP in southern Xinjiang during warm seasons has exhibited multiscale fluctuations. The periodic variation in TP in the mountainous and plain areas is consistent with their respective LSP. The most significant 2-3 year variation period occurred from 2005 to 2013.The main variation periods of CP in the mountainous and plain areas occurred after 2000. The results of this study provide a scientific basis for research on precipitation mechanisms, artificial precipitation enhancement operations,and water resource management in southern Xinjiang.