城市阻碍效应对局地台风降水的影响

城市阻碍效应是城市化影响降水形成过程的可能物理机制之一,在于其改变了风场、风场辐合,甚至改变了天气系统本身,进而改变了湿度平流,最终影响城市降水的落区、强度。风速越大,城市阻碍效应越明显。现有关于下垫面对台风降水影响研究主要着重分析地形及地表状况对台风降水落区及强度的影响,但对作为下垫面因子之一的城市对台风降水的影响作用考虑明显不够。全面系统回顾国内外有关城市阻碍效应对降水影响研究进展,以及下垫面对台风降水影响研究进展。上海是我国城市化程度最高的城市,同时平均每年受到2～3个台风影响。已有研究关注到了城市阻碍效应对上海局地台风降水影响作用,但是,对于表征台风降水的城市阻碍效应还存在明显不足。最后具体给出了未来有关城市阻碍效应在上海局地台风降水研究中的应用思考。

Study of Urban Barrier Effect on Local Typhoon Precipitation

Urbanization has changed the surface properties and characteristics, and more attentions have been paid to its influence on weather and climate. The urban barrier effect is one of the possible physical mechanisms for the urbanization to influence the formation process of precipitation. The urban barrier effect changes the wind field, wind convergence and even the weather system itself, and further changes the humidity advection, eventually affecting the urban precipitation location and intensity. The greater the wind speed, the more obvious the barrier effect of the city. However, current studies on the effect of underlying surface on typhoon precipitation mainly focus on the impact of topography and surface conditions on typhoon precipitation location and intensity, but the influence of cities as one of underlying surface factors on typhoon precipitation has not been considered enough. In this paper, the research progress on the impact of urban barrier effect on precipitation and the influence of underlying surface on typhoon precipitation are reviewed. Shanghai is the most urbanized city in China, and it is affected by 2-3 typhoons every year on average. Previous studies have focused on the influence of urban barrier effect on local typhoon precipitation in Shanghai, but there are still obvious deficiencies in characterizing the urban barrier effect of typhoon precipitation. Finally, the paper points out the application of urban barrier effect in the study of local typhoon precipitation in Shanghai in the future.