Role of the Tian Shan Mountains and Pamir Plateau in Increasing Spatiotemporal Differentiation of Precipitation over Interior Asia

Numerical simulations were conducted to determine the impact of the Tian Shan Mountains and Pamir Plateau on arid conditions over interior Asia. These topographies are crucial for the differentiation of the precipitation seasonality among the subregions in the west, east, and north of the Tian Shan Mountains and Pamir Plateau, namely, arid central Asia, the Tarim basin, and the northern plains. Before the uplift of the Tian Shan Mountains and Pamir Plateau, the precipitation seasonality over the east arid subregion was consistent with that over the west arid subregion, with maximum rainfall in spring and winter and minimum rainfall in summer. After the uplift of the Tian Shan Mountains and Pamir Plateau, the original precipitation seasonality in the west was strengthened. As the precipitation in the east arid subregion increased in summer but decreased in winter and spring, the precipitation seasonality in the east changed to peak in summer, while the precipitation in the north arid subregion showed the opposite change. The precipitation alteration corresponded well with the change of vertical motion. With the modulation of atmospheric stationary waves, the remote East Asian monsoon was also impacted. Though enhanced southerly wind blew over East Asia, the monsoon precipitation over the east coast of China and subtropical western Pacific Ocean was significantly reduced as an anticyclonic circulation appeared. The Tian Shan Mountains and Pamir Plateau also contributed to the intensification of the East Asian winter monsoon.