The Numerical Simulation And Data Assimilation Of A Rainstorm In Fujian

A heavy rainfall during 6-7 June 2006 in the Fujian area is diagnosed by using the conventional observational datasets and FY2C TBB data. In order to understand the physics mechanism of this rain-storm process, the numerical simulation of the rain gush is simulated by the fine-meshed WRF mesoscale numerical model developed by PSU/NACR.Analysis of the output data indicate that WRF model successfully reveals the circulation's evolution and the distribution of rainfall belt. The LLJ makes the convective instability and the upper jets keep the convergence at low level and divergence at high level, which give rise to the strong vertical movement. The interaction of the LLJ and ULJ is the important mechanism of the outbreak of the heavy rain. The strong rainfall takes place around the left exit of the LLJ andthe right of the northwesterly upper jet at 200hPa. 850hPaθ_se present typical"Ω"type. Highmoisture and energy keeps the rainfall maintaining and strengthening. The convergence field non-homogeneously located on the low-level shear line and the center of the rainfall is adjacent to the maximum vertical velocity. The two sides of area exist vertical secondary circulation. The MPV (positive at upper-level and negative at low- level) contribute to the strong ascending motion.The paper also assimilate through the infrared and water vapor channel cloud drift wind data to verify the performance of assimilation and the effect. The results of the assimilation of the model are not very satisfactory, and for 2005 July 11 to 12 along the Jiangsu-Zhejiang rainstorm for example, have made significant effect of assimilation. It also proves that a different example of Background assimilation of random adaptability. In future work, how to select the most suitable background error covariance is depending on a number of cases for further assimilation of comparative test and design a more reasonable assimilation program.