Abstract : 2E.2
A diagnostic analysis of the impact of the complex terrain of Tibet Plateau to a heavy rainfall event

Jing Chen, Chuan Li, Guangbi He
chenj@cma.gov.cn
Institute of Plateau Meteorological

With the mesoscale data provided in a high resolution numerical model, this paper analyzed diagnostically the impact of the complex mesoscale terrain at the east side of the Tibetan Plateau on the formation and development of severe local 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 the northwest Sichuan and the upper branch of Yellow River. The terrain structure of the east side of Tibetan Plateau makes the high energy tongue and energy front in the lower layer placed in Sichuan Basin and helped establish unstable potential energy stratification in the lower troposphere of Sichuan Basin. The accumulation of water vapor in the lower troposphere in 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 east and west wind and the steep landform, stimulating the release of the unsteady 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 dynamical feature of this heavy rain scenario is that the high-temperature, high-humidity and strong vorticity column only appear in the lower troposphere, which is very different from that of mold rain.