Implementation of the Land Surface Processes into a Vector Vorticity Equation Model (VVM) to Study its Impact on Afternoon Thunderstorms over Complex Topography in Taiwan

Abstract

In this study, we aim to evaluate the impact of fast land-atmosphere interactions on the afternoon thunderstorm in Taiwan through high-resolution meteorological simulations. For this purpose, the Noah land surface model (LSM) is implemented into the vector vorticity equation cloud-resolving model (VVM) with corresponding realistic land surface data of Taiwan into the coupling system, called TaiwanVVM. Two idealized experiments are conducted by giving the same surface forcing but one with direct land-atmosphere coupling from Noah LSM (called Coupled experiment) and the other with prescribed surface fluxes (called Prescribed experiment). Our results show that the fast land-atmosphere interaction over complex topography has a significant influence on rainfall intensity, especially in the heavy precipitating region where the interaction is strong. Without direct coupling between the land surface and the atmosphere in the Prescribed experiment, the diurnal intensity is suppressed by 50% over whole Taiwan and 70% for East Taiwan. Our findings demonstrate that the intensity of the afternoon thunderstorm is sensitive to fast land-atmosphere interactions by modifying local circulation in the mountainous region of Taiwan.