Abstract:

Precipitation acts as a crucial supply for mountain glaciers, and its water vapor source closely correlates to the amount of precipitation. This study focuses on the modern glacier distribution area of Ulugh Muztagh in the eastern Kunlun Mountains, analyzing water vapor sources in the region from 2005 to 2022 using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the Global Data Assimilation System (GDAS). Employing backward trajectory analysis, we reveal the source and regularity of water vapor in the Ulugh Muztagh region and discuss its seasonal changes. The results show that the water vapor source in the Ulugh Muztagh area mainly extends to the Eurasian interior along the midlatitude westerly belt and is divided into three routes entering the Qinghai-Tibet Plateau from the Tianshan Mountains, the Pamir Plateau, and over the high-altitude stratosphere. On the Qinghai-Tibet Plateau, water vapor from the Indian Ocean either moves northward over the Himalayas or turns northwestward to merge with the westerly circulation into the plateau’s hinterland. Land-source water vapor, entering from the Pamir Plateau and Tianshan Mountains, accounts for 62.52% of the total water vapor in the Ulugh Muztagh area. Meanwhile, sea source water vapor, comprising high-altitude water vapor from the westerly belt (Atlantic water vapor) and the Indian Ocean, accounts for 37.48% of the total water vapor. Notably, we find that the proportion of water vapor from the sea source has increased steadily over recent decades. Analyzing multiyear seasonal averages for water vapor, we find a notably high proportion of locally recycled water vapor in the summer, comprising 22.64% of the total. This study’s outcomes offer valuable insights into the water cycle dynamics of the Ulugh Muztagh area in the East Kunlun Mountains.

Key words: Ulugh Muztagh Mountains, HYSPLIT model, sources of moisture, East Kunlun Mountains