With mesoscale data from a high-resolution numerical model, this paper analyzes the impact of the complex mesoscale terrain at the eastern edge of the Tibetan Plateau on the formation and development of a local severe storm. The result shows that the dynamic blocking effect of the Tibetan Plateau terrain affects the moisture transfer channel in this heavy rain scenario and brings about the formation of a strong water-vapor convergence center in northwest Sichuan and the upper branch of Huang He (Yellow River). The terrain structure of the east side of the Tibetan Plateau places a high energy tongue and energy front in the lower layer of the troposphere of Sichuan Basin and helps establish unstable potential energy stratification in the lower troposphere of the Sichuan Basin. The accumulation of water vapor in the lower troposphere in the Sichuan Basin is the major reason for the establishment of unstable potential energy stratification. The steep terrain of the east side of Tibetan Plateau strengthens the ascendant motion. The strongest updraft movement occurred in the convergence area of the vertical shear of cast and west wind and the steep landform, stimulating the unsteady release of energy and rapid development of the strong convection. The process is also accompanied by a mesoscale vortex in the east side of the Plateau. The most significant thermal and dynamic feature of this heavy rain scenario is that high temperature, high humidity, and strong vorticity columns appear only in the lower troposphere, which is very different from Mei-Yu. ("Mei-Yu" in Chinese and "Baiu" in Japanese refers to the frontal precipitation caused by Mei-Yu front, a persistent east-west zone of disturbed weather during early summer which is quasi-stationary and stretches from the east China coast, across Taiwan, and eastward into the Pacific Ocean south of Japan.)
展开▼
