Integrated Soil Physical Schemes in Land Surface Modeling over the Tibetan Plateau

Over the past decades, many efforts have been made to enhance the performance of land surface models (LSMs) over the Tibetan Plateau (TP), but land surface modelling over the TP still faces great challenges. Given that some important findings have not been well applied and integrated in this region, this study aims to integrate the key soil physical schemes documented in previous papers to better represent the land processes in the TP. The selected model is the community Noah LSM with multiparameterization options (Noah-MP). Based on previous findings, this study evaluates the soil vertical stratification, a typical phenomenon beneath alpine meadows. For the energy equation, convection of heat by moving water is added as well as convection of latent heat by evaporation within soil. Also, several models for soil thermal conductivity are evaluated, taking the effect of soil organic matters into account. For the mass equation, the scheme by Ross (2003) is implemented to estimate soil hydraulic conductivity at the interface of two adjacent soil layers. The roots’ impact on soil saturated hydraulic conductivity is also tested. For thermal roughness length, the parameterization by Yang et al. (2008) is implemented. Moreover, a restriction item is added for soil surface evaporation to guarantee that actual evaporation does not exceed the maximum water supply from the top soil layer. In the future, more applications of combining the advantages of different soil physical schemes are needed to improve land modeling over the TP.