Numerical Simulation And Feature Analysis Of Cyclonic Precipitation And Typhoon Precipitation

Using observational data and NCEP data, A heavy rain occurred Qidong, Jiangsu province and 'RANANIM' typhoon are stimulated in this paper and compared their thermodynamics and dynamic field on the output of MM5 (V3)The severe rainstorm of Qidong is a very local rainstorm at August 15th-16th 2002. Using the model output with high spatial and temporal resolution, we study the characteristic and mechanism of the local heavy rain. The results show that the main influence of this rainstorm is a meso-β scale cyclone developing form a shear line. The cyclone crosses the Yangtze river, moves on Qidong, developes on this area and formes a potential vorticity column to generate heavy rain. In this process, we also find it exists obvious local circulation and the wind filed appears clockwise change by time. When the sea breeze happens, temperature and relative moisture will be change. In accordance with the local character of this heavy rain area and the peculiar terrain of Qidong, a terrains sensitivity test is designed. After removing terrain of Qidong, the precipitation area and intensity have a great change.The mesoscale numerical model MM5(V3) is also used to simulate 'RANANIM' typhoon. The character of typhoon rainfall area, wind field and center construction are analyzed. The results are as followed: (1) when typhoon is on sea, the center construction is uniform. Before landing or on the land, it becomes non- uniform affected by surface friction and typhoon energy transport and so on; (2) precipitation distributes the front or right of typhoon moving tracts. Otherwise, the precipitation area has a good correspondence tohigh center of 850hPa wind field.Thermodynamics and dynamic field of typhoon is compared with former cyclone. It indicates that ascending velocity rainfall and convergence of the cyclone can stronger than typhoon's. The vertical section of typhoon rainfall's constant potential temperature appears very obvious saddle type and the precipitation area is under the drooping area of high-level constant potential temperature. Symmetry and convective instability exist in low-level of troposphere in both processes. In the cyclone precipitation, the instability also appears in high-level of troposphere...