考虑地形和土地覆盖影响的参数化台风风场模拟

现有参数化台风风场模型通常采用单一地表粗糙度假设,忽略地形和土地覆盖的影响,使得参数化台风风场模型不能真实反映台风风场。本文基于GTOPO30(Global Topographic Data of 30 arc seconds)全球数字高程数据和USGS(U.S.Geological Survey)全球土地覆盖数据,将地形地貌效应等效为地表粗糙长度,建立了受西北太平洋台风影响的东亚地区的地表粗糙长度空间分布;并对比验证了3个典型地貌的地表粗糙长度。然后,对参数化台风风场模型进行了适当修正,使其能耦合地形起伏对风场产生的抬升和沉降作用。以WRF(Weather Research and Forecasting)模式的模拟结果为基准,采用3个历史台风案例,考察了地形地貌对参数化台风风场模拟的影响。对比结果表明,考虑地形地貌效应可以显著提升参数化台风风场模型对台风空间结构的模拟能力。考虑地形地貌影响的参数化台风风场模型的模拟结果与实测结果吻合较好。

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.