Intense Orographic Precipitation Associated with Typhoon Talim (2005) in China

The intensity of Typhoon Talim (2005) weakened rapidly after landing on Fujian Province of china on September 1, 2005. The formation of tropical depression was at 14 o'clock on September 2. However, from at 13 o'clock on September 2 to at 23 o'clock on the 3rd, the tropical low-pressure area caused a 940mm precipitation center to form a big storm rainfall in Lushan Mountain of Jiangxi Province of china, inducing landslides and debris flows once, and resulting in severe economic losses and casualties. Preliminary analysis shows that the water vapor convergence of tropical low pressure is not very strong at 850hPa, and there is no large-scale water vapor conveyor belt, or a wider range of water vapor transport around the low-pressure. Therefore, it should answer what is the source of water vapor to support such a strong precipitation. This paper will use the measured precipitation data combining with the data of NCEP, to study where does the water vapor come from. The main method is to diagnose every part of completed moisture equation in order to determine the real source of water vapor. At the same time, this heave precipitation relates to the structure of low-pressure center. This article, using the measured precipitation data, calculates vertical velocity and latent heat release Q, and thus anti-calculate the potential-vorticity corresponding to the latent heat. Then to study the thermal field and dynamic field of the appropriate atmosphere, in order to determine which of these small-scale structure related to the precipitation and what is the dynamic mechanism. Around Lushan Mountain in china, there is Huangshan in the east, Dabie Mountains in the north, and Nine-Ridge Hill in the west. Formed by these terrains, the region is similar to the tropical depression. The existence of a new dynamic mechanism is worth studying, so we propose some non-dimensional numbers to descript their dynamic characteristics. Through the above three aspects of analysis, this paper attempts to give the dynamic interpretation about this tropical depression stagnating and generating torrential storm rainfall.