High-resolution Numerical Simulation And Diagnostic Analysis Of Precipitation Associated With Landfalling Typhoon Fanapi (1011)

In this thesis, observational analysis and numerical simulation of the landfalling and strong precipitation processes of Typhoon Fanapi (1011) have been studied based on NCEP/NCAR1°x1°global reanalysis data, the CMA best track data, Micaps precipitation data, radar and satellite data, and the non-hydrostatic mesoscale numerical model-WRF (Weather Research and Forecasting) model. Main conclusions are as follows:(1) Typhoon Fanapi, the strongest TC generated in Northwest Pacific and the South China Sea during2010, is the only twice-landfalling typhoon over China. Observational analysis have been performed by using satellite cloud image, radar reflectivity, CMA best track,24-hour precipitation, and the high and low altitude circulation configuration analysis during the landfalling process. The results show that the tortuous track and twice landfalling of Fanapi over China mainly due to the guidance of the circulation field, especially after its landfall in China mainland. The continental high pressure over the China mainland blocks Fanapi from proceeding northward so that it moved to the west until dissipated.(2) Non-hydrostatic mesoscale numerical simulation model WRF is used in the high-resolution simulation of the twice-landfalling process associated with Typhoon Fanapi. Detailed comparisons are taken between various observations and the simulation. The results show that the simulation reproduced the development, evolution and twice-landfalling process of Typhoon Fanapi to a significant extent. The simulated track is rather similar with the observation. Only in the rear of the up-to-five-day simulation, that is after the landfalling over mainland China, the simulated typhoon track showsrelatively larger difference. At the same time, the simulation of intensity evolution is proved to be a success, as the simulation and observation evolve consistently in trend. The simulation reproduced the development and evolution of large-scale circulation during the lifespan of Fanapi, as well as the interaction between typhoon circulation and the circulation systems around. The main characteristics of simulated radar reflectivity and6-hour accumulated precipitation are rather similar with observations too.(3) Diagnostic analysis using high resolution simulation data and various parameters, such as vertical divergence flux, moist potential vorticity, thermodynamic shear advection, Q-vector divergence, vertical helicity, thermal vertical helicity and convective vorticity vector, are performed on the strong precipitation process. The results show that the distributions of the parameters are over the vicinity of precipitation regions. The parameters and precipitation have similar spatial distribution and temporal evolution, that is to say, they have some indications in the rainfall system. Among these parameters, vertical divergence flux, Q-vector divergence, vertical helicity and thermal vertical helicity have better correspondence with the heavy rainfall region.The innovative in the dissertation are listed as follows. First of all, the landfalling process (5days) of typhoon Fanapi is carried out in high resolution simulation with the non-hydrostatic mesoscale numerical model WRF and achieves success. Secondly, diagnostic analysis on the strong precipitation process based on various parameters (vertical divergence flux, moist potential vortex, thermodynamic shear advection, Q-vector divergence, vertical helicity, thermal vertical helicity, convective vorticity vector) have been performed, and the differences of their indications on precipitation are discussed.