Quantitative assessment of the impact of soil-atmosphere coupling on regional climate in the low-latitude highland of Southeast Asia

The low-latitude highland (LLH) of Southeast Asiais one of the hot spots of land-atmosphere coupling, and its variations in the soil temperature and moisture have a significant effect on the regional and Asia climate. In this study, numerical sensitivity tests of the impact of soil temperature and moisture on regional climate in the LLH were conducted using the Weather Research and Forecasting (WRF) model, and the mechanisms of which were explored. The following are the primary conclusions: the Land-Atmosphere Coupling (LAC) index reaches its highest value of 0.46 in spring, indicating the strong land-atmosphere coupling in LLH. The numerical simulation reveals that soil temperature-atmosphere coupling most significantly affects air temperature and precipitation in winter and autumn, with contributions of 35.5% and 1.4%, respectively. In contrast, soil moisture-atmosphere coupling has the greatest impact on temperature and precipitation in summer, contributing 14.4% and -3.0%, respectively. The mechanism analysis of spring air temperature and precipitation changes shows that, for soil temperature-atmosphere coupling, air temperature is primarily influenced by net longwave radiation, as for soil moisture-atmosphere coupling, the primary influencing factor is sensible heat flux. In terms of spring precipitation, evapotranspiration is the key driver in both soil temperature and moisture-atmosphere coupling, with significant contributions exceeding 30.0% for each.