The arid/semi-arid region of East Asia: A hot spot of soil temperature-atmosphere coupling

Over recent decades, land-atmosphere interactions have received increasing attention in the scientific literature. There are a number of studies that have reported the important role of soil moisture, vegetation, and snow cover in influencing climate variability. Soil temperature, another important component of land surface, can influence the climate through its effects on surface energy and water budgets and resulted changes in regional atmospheric circulation. Only a few published studies have explored the effects of soil temperature on climate variations. In particular, the role of soil temperature feedbacks for interannual climate variability has been less discussed. The goal of the present study is to investigate the role of soil temperature-atmosphere coupling in influencing interannual variability of summer surface air temperature over East Asia with a regional climate model (RCM). This is achieved by carrying out two long-term Weather Research and Forecasting (WRF) model simulations, with and without subsurface soil temperature feedbacks. Results indicate that subsurface soil temperature feedbacks depend on climate regimes, mainly affecting summer surface air temperature variability over the arid/semi-arid regions. Over these areas, subsurface soil temperature feedbacks play a dominant role in amplifying daily mean surface air temperature variability with a stronger effect on daily minimum temperature than that on daily maximum temperature. This study highlights the importance of soil temperature feedbacks to summer surface air temperature variability over the arid/semi-arid regions. Outside the arid/semi-arid regions, the important role of soil moisture over land areas for summer temperature variability is previously identified. These findings together suggest that the land makes a dominant contribution to summer temperature variability over land areas of East Asia. Knowledge of land-climate relationships could aid in improving summer climate prediction over East Asia.