The impacts of late spring soil moisture in the Tibetan Plateau on summer precipitation in eastern China

The Community Land Model version 4.5(CLM4.5), driven by the atmospheric forcing dataset CRUNCEP, was used to simulate the spatial and temporal characteristics of soil moisture across the Tibetan Plateau from 1981 to 2016. Compared with station data and two reanalysis products (i.e., the ERA-Interim and GLDAS-CLM), it is found that CLM4.5 can well reproduce the spatial and temporal variations of soil moisture in the Tibetan Plateau. This study reveals the relationship between soil moisture on the Tibetan Plateau in May and summer precipitation in eastern China and the physical mechanism for the impact of soil moisture on summer precipitation. Singular value decomposition (SVD)analysis shows that the surface soil moisture in the south-central Tibetan Plateau was positively related to the summer precipitation in South China and negatively related to that in the middle and lower reaches of the Yangtze River and Northeast China. The soil moisture in the western Tibetan Plateau was the opposite of that in the south-central region. The wetter the surface soil moisture in the south-central Tibetan Plateau in May was, the lower the surface temperature, sensible heat flux and net longwave radiation flux, and the higher the latent heat flux and net shortwave radiation flux and leading to weaker surface heating. In contrast, lower surface soil moisture in the western Tibetan Plateau led to stronger surface heating. This led to a weaker western Pacific subtropical high and a more northerly rain belt. The weather in South China was controlled by large cyclonic circulations forming convergences and updrafts that led to more rainfall in South China. The precipitation in the middle and lower reaches of the Yangtze River and Northeast China was less under the control of the anomalous anticyclone than that in South China, and vice versa.