Abstract:

The north slope of the Kunlun Mountains is an essential corridor for the construction of the core area of the Silk Road Economic Belt. It is located in the inland arid zone of Northwest China, where torrential rains are sudden, short-lived, and disaster-heavy. In the actual forecasting operations, there are more empty reports and omissions of torrential rains in the north slope of the Kunlun Mountains, which leads to insufficient disaster defense in this region. This study used precipitation and reanalysis data from the national meteorological stations on the north slope of the Kunlun Mountains from 1961 to 2023 to reveal the characteristics of long-term changes in heavy rainfall in different regions of the north slope of the Kunlun Mountains and the differences in circulation. The results revealed that (1) from 1961 to 2023, the number of heavy rain days and the amount of heavy rainfall in the western and central sections of the northern slope of the Kunlun Mountains exhibited an increasing trend, with the western section exhibiting a more pronounced increase. The cumulative number of heavy rain days and heavy rainfall in the western section was greater than in the central section. However, the difference in extreme rainfall amounts between the two sections was not significant. In the western section, the amount of heavy rainfall during the warm and humid phase was greater than that during the warm and dry phase, while the opposite was observed for the central section, indicating different levels of response to climate transitions. (2) the spatial distribution of heavy rain days and heavy rainfall volumes on the western section of the northern slope exhibited a characteristic of “more in the east and less in the west,” while the central section displayed a pattern of “more in the middle and less on the sides.” The spatial distribution of average heavy rainfall and cumulative heavy rainfall volumes is consistent in the western section but opposite in the central section. (3) over 90.0% of the stations on the northern slope of the Kunlun Mountains have experienced short-duration heavy rainfall events, which is higher than the average for southern Xinjiang; nonshort-duration heavy rainfall events predominantly characterize the western section (central section). The persistence of heavy rainfall events on the northern slope is relatively poor, with a majority occurring at night, and the average precipitation duration of heavy rainfall events in the western and central sections is similar. (4) the typical configuration of the main weather systems causing heavy rainfall in the western and central sections of the northern slope is the same, which increases the difficulty of precise forecasting for the fine-scale distribution of heavy rainfall in the Kunlun Mountains. The research findings can deepen our understanding of the uniqueness of heavy rainfall in arid regions and provide references for enhancing the defense capabilities against heavy rainfall on the northern slope of the Kunlun Mountains.

Key words: heavy rainfall, climatic features, daily variability, weather systems, northern slope of the Kunlun Mountains