Influence of Land Surface Scheme on Rainfall Simulation over Northern Thailand using WRF Model

Abstract

Atmosphere-land interactions are important processes to the global climate system. Land surface scheme in numerical weather prediction models provide heat and moisture flux between land and atmosphere that are significant for rainfall formation. Precipitation in heavy rainy month in normal climate year of September 2013 was simulated to examine the effects of land surface scheme over Northern Thailand using the Weather Research and Forecasting Model (WRF) Version 3.4. Four different land surface schemes were tested: The Dudhia 5-layer thermal diffusion (SLAB), The Noah LSS (Noah), The RUC LSS (RUC) and Noah-MP (multi-physics) Land Surface Model (Noah-MP). The simulated results were evaluated with 99 rain gauge stations in Northern Thailand. The results show that the simulated rainfall is sensitive to different land surface scheme with relative differences of 23-62%. Simulated precipitation using SLAB is the best performance in comparison with other schemes. Monthly average of simulated precipitation of SLAB is more close to the observation than simulated rainfall using Noah RUC Noah-MP and No land surface scheme (No LSS). The study result is useful for model configuration of appropriate parameterization in weather simulation in this region.