Assess the impacts of different land cover datasets on land surface hydrological process in Community Earth System Model (CESM)

By changing matter and energy exchange, biogeochemical process and geophysical process, land use and land cover changes have crucial effects on the earth system modelling. Previous studies have focused on reconstructing the land use and land cover change to be a continuous changing process over time considering human and natural factors. The real land cover change processes have rarely been taken into consideration in the simulation of earth system. Using Gong global land cover mapping products (1985-2015) and the Lawrence land cover dataset (default) in CESM, this study have quantitatively compared the differences in plant function types (PFT) between two products. The results show the land cover changes in default dataset are slowly changing processes with little variation from year to year. In contrast, the Gong global mapping products express a noticeable drastic change tendency between adjacent years. Driving the model with different land cover datasets, our results indicates that globally land evapotranspiration (ET) is dramatically impacted by the land cover changes, especially in areas with distinct tree changes. Also the land cover change can cause a certain proportion variation in soil water (-50%-65%) and runoff (-60%-60%, even >90% in some special grid points) in a global scale. This study estimates the substantial effect land use and land cover changes can have on the land surface hydrological process in earth system modelling.