Sensitivity Analysis of the Noah-MP Land Surface Model for Soil Hydrothermal Simulations Over the Tibetan Plateau

The Tibetan Plateau (TP) features unique and highly heterogeneous soils, terrains, vegetation, and climate. Accurately modeling complex freeze-thaw processes and their hydrothermal impacts remains a great challenge. This study focused on deciphering the spatiotemporal variability of diverse parameterization schemes in the soil hydrothermal simulations using the Noah-MP land surface model. We first discussed the spin-up time required by the model to reach the equilibrium state, and then performed a sensitivity analysis of these schemes. The Moderate Resolution Imaging Spectroradiometer land surface temperature and Soil Moisture Active Passive remote sensing products were used as benchmarks to evaluate the schemes' performance. Results show that longer spin-up times are required in permafrost regions owing to water phase changes. Ground temperature and soil temperature are mainly sensitive to energy-related schemes. Vegetation-related schemes play an important role after the growing season begins on the southeastern TP. Soil water content shows strong sensitivity to schemes related to both water and energy transport. However, the sensitivity of these energy-related schemes is weakened when simulating total soil moisture, including the total amount of water and ice, indicating that these schemes have marked impacts on soil freeze-thaw processes. These results reveal the different spatial (both regional and depth-related) and temporal effects of parameterization schemes; we also provided a preliminary selection of these schemes at a regional scale that could facilitate the further improvement of the soil hydrothermal simulations on the TP.

Automated summary

This study focused on the spatiotemporal variability of diverse parameterization schemes in the soil hydrothermal simulations using the Noah-MP land surface model. Results revealed the different spatial and temporal effects of parameterization schemes, with energy-related schemes being sensitive to ground and soil temperature, and vegetation-related schemes playing a role after the growing season begins. Soil water content showed strong sensitivity to schemes related to both water and energy transport, while the sensitivity of energy-related schemes weakened when simulating total soil moisture, indicating their impact on soil freeze-thaw processes.