研究期間：10108~10207;Model initialization should consider the effect of asymmetric structures associated with a typhoon near landfall due to the interaction with topography. This project will use both 3DVAR and 4DVAR to assimilate available data including satellite near-surface wind speed, GPS ground-based and radio occultation observations to investigate the impact of these data assimilation on the intensity, track and local intense rainfall of typhoons nearing Taiwan, with the focus on recent typhoons (e.g., Morakot, Fanapi, and Megi) and future typhoons. Along this line, the PV-inversion retrievd vortex will be used to provide a three-dimensional complete circulation (wind, pressure and temperature) from the quasi-balanced flow and divergence field (including vertical velocity) for typhoon initialization in comparison to bogussing data assimilation (BDA). The project lasts for three years and has an inclination to the combined effects of radar reflectivity and radial velocity as assimilated with the BDA vortex or PV-retrieved vortex. The primary interest will be in the impact of the multiple time levels and high spatial density radar data on the simulation of the typhoon nearing landfall. The first year will be focused on assimilation and simulation using WRF and WRF 3DVAR, in addition to PV inversion works for selected typhoons, with sensitivities to the changes in sea surface temperature on the typhoon evolution through a 1-D mixed-layer ocean model. The second year continues the works of the first year and will attempt to assimilate the radar data using WRF cycling 3DVAR and WRF 4DVAR to investigate the influential role of the vortex spin-up and asymmetry. The last year would try to assess the performance of a combination of vortex initialization and data assimilation. Based on the best simulation among the model experiments, the dynamical processes, the topographical effects and possible mechanisms for super-intense rainfall associated with selected typhoons will be analyzed in detail.
