Analysis of the Contribution of Water Vapor from the Arabian Sea to the Local Rainstorm Process in Southern Xinjiang

Abstract

In order to investigate the water vapor sources of summer precipitation in southern Xinjiang, especially Hotan area. Based on NCEP FNL 1°*1° analysis data and Xinjiang meteorological bureau area numerical operation prediction, a local precipitation event in southern Xinjiang on June 26 was analyzed, and the results showed that the water vapor involved in this process originated from the northwestern Gangetic Plain and was transported along the Indus River plain and over the northwestern end of the mountains. Driven by the Iranian low-pressure trough, water vapor at 500 hPa was transported across the northwestern end of the Gangdise Mountains, past Georgoli Peak, and northwest over the Kunlun Mountains to arrive in southern Xinjiang. And a zonal profile was made along the northern foothills of the Kunlun Mountains (latitude 36°N), and the width was limited to the longitude range [70°E, 80°E] and the height range [500 hPa, 300 hPa] according to the water vapor channel scope of the process. In the first 24 hours after the end of the precipitation process, the total water vapor input and transmission amount was more than 3*107kg. That is, the water vapor transmitted over the preceding 24 hours far exceeded the precipitation during the precipitation event. So, under the combined influence of the Iranian vortex and equatorial vortex, moisture from the Arabian Sea at heights above 500 hPa can directly cross the Indus River plain traverse the Qinghai-Tibet Plateau and reach the southern region of Xinjiang. Therefore, the southern upper air passage is an important water vapor source in southern Xinjiang. Under appropriate conditions, it can cause short-term local heavy rainfall and lead to secondary meteorological disasters such as debris flow.