初始场水汽通量在一次登陆台风降水模拟中的作用

Effects of water vapor flux in the initial condition on precipitation simulation of a landfall typhoon

用三维变分同化方法,通过同化加密地面观测资料和X波段雷达观测资料,研究初始场陆地侧水汽通量对台风“狮子山”登陆期间降水模拟效果的影响.结果表明,同化加密地面资料能够明显改进初始场陆地侧大气边界层的热动力场,通过减弱海-陆热力对比及陆地向登陆台风的大气边界层东北的水汽通量,改善登陆台风外围雨带影响下的沿岸陆地-海洋两侧地区降水的模拟效果. X波段雷达资料通过增强初始场中雷达探测范围内的低层大气水汽通量改善登陆台风外围雨带降水的模拟效果.

Based on the three-dimensional variation method,we investigated the effects of water vapor flux from land surface in the initial condition on the precipitation simulation during the landfall of typhoon"Lionrock",by assimilating dense in-situ ground data and X-band radar data.The results showed that the assimilating dense in-situ ground data could evidently improve the thermodynamic field in the boundary layer of the environment at the initial condition,improve precipitation simulation in the coastal region by weakening the thermal difference between land and ocean,and weaken water vapor flux in the boundary layer from northeast in land region to the landfalling typhoon.Assimilating X-band radar data could improve precipitation simulation by enhancing the water vapor flux in the boundary layer within the radar detection range in the initial condition.