Chinese researchers recently evaluated a suitable soil thermal conductivity (STC) scheme for use in land surface process models (LSMs) in permafrost regions on the Tibetan Plateau (TP), which could accurately simulate soil thermal regimes in permafrost regions. 

STC is essential parameter for revealing thermodynamic changes and projecting changes in soil thermal regimes. However, the incorporation of different STC schemes into LSMs can afford large errors. Thus, to accurately simulate soil thermal regimes in permafrost regions, a suitable STC scheme in LSMs is important. 

Using the latest version of the Community Land Model (CLM5.0), a research team led by Prof. LI Ren from the Northwest Institute of Eco-Environment and Research Institute (NIEER) of the Chinese Academy of Sciences (CAS) selected nine normalized STC schemes and evaluated their performance in simulating STC and soil temperatures with in situ measurements in permafrost regions on the TP.

The researchers investigated the differences and uncertainty factors resulting from different STC schemes in CLM5.0. Finally, they recommend a suitable STC scheme for use in LSMs in permafrost regions and summarized possible efforts to obtain more accurate results in the future. 

The results showed that the category comprising minerals, soil organic matter, and gravel soil afforded better performance at most sites than the other categories. The BA2005 schemes ranked top among the STC schemes at most sites in permafrost regions on the TP with an average root-mean-square (RMSE) decreased of 56.2% and 15.0% in simulating STC and soil temperatures compared to the default scheme (LS2008). 

The researchers also investigated possible causes affecting the results. The results indicated that soil moisture is a determinant, slight change in soil moisture may cause large changes in thermal processes. In addition, soil properties, atmospheric forcing data, and model structures also yielded error in the simulated results. 

The research has been published in Geoderma as an article entitled Evaluation of soil thermal conductivity schemes incorporated into CLM5.0 in permafrost regions on the Tibetan Plateau.  

This work was financially supported by the State Key Laboratory of Cryospheric Science (SKLCS–ZZ–2021), the National Natural Science Foundations of China (42071093, 41721091, 41941015, 41690142, 41771076, 42071094; 41671070). 

Contact: 

LI Ren 

E-mail: liren@lzb.ac.cn 

State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou, China.