夏季，青藏高原上空中小尺度对流系统（MSSC）多发，这些MSSC不断向高原大气输送热量和水汽，MSSC的变化直接影响高原加热效率，从而对局地乃至东亚区域天气气候变化产生显著影响。土壤湿度的空间不均匀性是触发MSSC的重要因子之一。反过来，MSSC降水也会改变局地土壤湿度。然而，目前对青藏高原陆-气相互作用过程和机理的认识尚十分有限。近些年来的研究表明，由于分辨率和积云对流参数化方案的原因，粗分辨率模式不能正确模拟观测到的土壤湿度与降水之间的反馈关系。本项目拟利用高分辨率（3km）的数值模式，关闭积云对流参数化方案，开展陆-气耦合模拟试验，显式地将夏季青藏高原土壤湿度与降水之间的耦合作用分离出来，定量评估高原陆-气耦合强度，研究高原陆-气耦合对MSSC的影响及其机理。该项目研究紧密围绕重大研究计划的总体目标，项目的实施将深化对青藏高原陆-气相互作用过程和机理的认识。

Meso- and small-scale convection (MSSC) occurs frequently over the Tibetan Plateau (TP) in summer. MSSCs transfer heat and moisture from the TP surface to the atmosphere, which alters the heating efficiency of TP and in turn modulates weather and climate over the TP and East Asian region consequently. Soil moisture and its spatial pattern can trigger MSSC on one hand. MSSC-related precipitation can also alter soil moisture on the other hand. However, our knowledge is very insufficient about the land-atmosphere interaction over the TP. Recent studies suggested that GCMs cannot correctly simulated the observed relationship between soil moisture and precipitation due to their coarse resolutions and cumulus convection schemes. In the proposed study, we will perform two sets of land-atmosphere coupling ensemble experiments by using 3-km WRF model with cumulus convection scheme closed, to explicitly isolate land-atmosphere coupling effect and evaluate the land-atmosphere coupling strength. The study aims to understand the soil moisture-precipitation coupling processes and investigate its influences on MSSC over the TP in summer. This study tightly tally the goal of NSFC major project. It is expected that the proposed research can deepen our understandings of change in land-atmosphere coupling system over the TP area and related mechanisms.