The Effect Of The Complex Topography On Heavy Precipitation At Heavenly Lake Of Tianshan

Although Xinjiang is located in the northwest arid region of our country, but the rainstorm caused flooding and mudslides is one of the main disasters. Although rainstorm occurred less special and the main precipitation is in Tianshan Mountains, but the rainfall intensity is particularly strong and rainstorm has a strong local nature. a heavy rainstorm happened on22-23June2010in Tianshan Tianchi is selected as a research case in this paper and6hours accumulated rainfall up to124mm. we successfully reappear this heavy rainfall process by using Weather Research and Forecasting Model. On the basis of analysis of the reasons for the occurrence of rainstorm, and focused on the impact of the flow structure and moisture transport under the effect of the topography of precipitation.Analysis results show that from west to east movement of multi-cell systems windward slope of the terrain before reaching the barrier slowdown and stagnation,and merged with the local convective cells generated windward slope, this is one of the reasons for this big rainstorm occurred; Bogda Mountains northwest flow in case of blocking, in addition to a portion of the airflow along the windward slope to climb beyond, Another part of the air flow around the body form a westerly flow and the west along the mountain climb, this westerly flow around the windward slope is greater than the flow velocity of the Northwest6m·s-1. Convection occurs enhancement confluence of two streams at the top of the times caused by heavy rain process provides dynamic conditions; In addition, the lower level before the windward slope flow velocity decreases with height, promoting and further enhance the windward slope of the flow field convergence, corresponding increase in cyclonic vorticity, generated an increase of precipitation on the windward slope effect.The storm water source process is mainly the Caspian Sea, the Arctic Ocean and local Il1. Water vapor channel is mainly two under700hPa:A high voltage is near the west side of the Ural Mountains to the Caspian Sea near the southerly flow of warm air northward transport, Another trough west of the Northwest Central Asia LLJ southward transport of water vapor to the Arctic Ocean; Under the conditions prevailing northwest flow, blocking effect and canalization Tianchi Mountains, Tianshan Tianchi lower west side of the formation of a strong moisture sink; Due to the blocking effect of the terrain, the water vapor mixing ratio of the same height, the value is greater than the piedmont of3g-kg-1after Hill. Tianshan mountain land surface evaporation strong local and high moisture content near the ground, Latent heat flux maxima in the Tianshan Mountains area.