Parametric typhoon wind field simulations by considering the effects of terrain and land cover

Instead of considering the effects of terrain and land cover, the existing parametric typhoon wind field models adopt the assumption of uniform surface roughness, which cannot predict typhoon wind fields correctly. Based on the datasets of global digital elevation (GTOPO30, Global Topographical Data of 30 arc seconds) and global land cover (USGS, U. S. Geological Survey), the effects of terrain and land cover are equivalent to the surface roughness length. The spatial distribution of surface roughness length of East Asia, which suffered by typhoons generated over the Northwest Pacific Ocean, is established. Then the surface roughness lengths of three land cover types are verified. The parametric typhoon wind field model is modified to couple the uplift and subsidence effects of wind field caused by terrain. Based on the simulation results of WRF (Weather Research and Forecasting), three historical typhoons are compared to investigate the influences of terrain and land cover on parametric typhoon wind field model. Comparison results show that considering the effects of terrain and land cover can significantly improve the simulation ability of parametric typhoon wind field model to predict the spatial structure of typhoons. In addition, the simulation results of this model with terrain and land cover are also in good agreement with observations.