Impact of soil organic carbon - gravel parameterization scheme on soil water and heat transport on the Tibetan Plateau

In this paper, the CLM5.0 organic carbon – gravel (OC – G) parameterization scheme was used to simulate soil temperature and moisture on the Tibetan Plateau from 1990 to 2018. Correlation between the simulated and observed soil temperature or moisture was higher, and the error was smaller, after the modification of the parameterization scheme. This improvement justifies the applicability of the scheme for soil hydrothermal simulations on the plateau. The effects of soil organic carbon (SOC) and gravel content on soil temperature and moisture across the plateau were also evaluated, and show that increasing SOC content increased soil moisture and decreased soil temperature, with the southeastern key area being most sensitive to SOC and gravel content. With increasing gravel content, soil moisture decreased and soil temperature increased, especially in the northwestern key areas. However, in general, soil on the plateau was more sensitive to changes in SOC content, and when the SOC and gravel content changed at the same time, the effects on soil temperature and moisture were a “cumulative” effect. The change directly affected the memory time of soil temperature and moisture in summer over the plateau. Specifically, when the organic carbon content was increased, the memory time of surface soil moisture increased in the northwest and decreased in the southeast. When gravel content was increased, the memory time of surface soil moisture decreased in the northwest but increased in the southeast, and the memory time of soil temperature remained largely unchanged. Changes to the abnormal duration may alter summer weather and climate in Eastern China.