Analysis of Terrain Height Effects on the Asymmetric Precipitation Patterns during the Landfall of Typhoon Meranti (2010)

The predictions of heavy rainfall in an accurate and timely fashion are some of the most important challenges in disastrous weather forecast when a typhoon passes over land. Numerical simulations using the advanced weather research and forecasting (WRF) model are performed to study the effect of terrain height and land surface processes on the rainfall of landfall typhoon Meranti (2010). The experimental results indicate that terrain height could enhance convection and precipitation. The heavy rainfall is concentrated on the west side of typhoon track, which is mainly associated with the distribution of deep convection. The terrain height exacerbated the asymmetric distribution of heavy rainfall. The most striking feature is that enhanced rainfall is mainly caused by secondary circulation, which is induced by terrain height and can be explained by a highly simplified theoretical model. Finally, it is worth pointing out that perturbation potential temperature or buoyancy processes forced by terrain height could be taken as an indicator for accurate prediction of heavy rainfall during the landfall of a tropical cyclone.