Terrain-Corrected Simulations of GPP and ET over mountainous region (Fujian Province, China)

Relative to flat surfaces, mountainous terrain alters the absorption of solar radiation by vegetation on sloping surfaces, leading to changes in mass and energy fluxes, including gross primary productivity (GPP) and evapotranspiration (ET). However, these effects are often overlooked in regional and global ecosystem models, and their impact has not been systematically considered. This dataset provides terrain-corrected simulations of GPP and ET using the Biosphere-Atmosphere Exchange Process Simulator (BEPS) model over a mountainous region (Fujian Province, China) for the year 2015. In BEPS, terrain effects are systematically accounted for through the following steps: (1) the satellite-derived leaf area index (LAI) is projected onto sloping surfaces, (2) canopy radiative transfer is modeled relative to the normal of the slope, and (3) the simulated fluxes are reprojected from sloping to horizontal surfaces. In Step (1), the LAI is calculated downward due to the increased surface area of sloping terrain relative to its horizontal projection. In contrast, Step (3) counteracts this effect by increasing the estimated fluxes. Due to the nonlinear relationship between fluxes and LAI, neglecting terrain effects leads to the underestimation of GPP and ET, particularly on sunlit slopes. This underestimation intensifies with increasing slope steepness, reaching approximately 11% for GPP and 33% for ET on slopes exceeding 40°. While these comparisons were derived from a manuscript with submissions in progress and are not included in the dataset, they highlight the potential underestimation of GPP and ET in existing global products over mountainous regions, emphasizing the importance of systematically accounting for terrain effects in Terrestrial ecosystem models (TEMs) modeling.

References:

Chen J M, Liu J, Cihlar J, et al. Daily canopy photosynthesis model through temporal and spatial scaling for remote sensing applications[J]. Ecological Modelling, 1999, 124(2-3): 99-119.

For any questions regarding this dataset, please contact:

Jianjie CaoFujian Normal UniversityEmail: [e-mail]

Rong WangFujian Normal UniversityEmail: [e-mail]