Effects of Crop Growth and Development on Land Surface Fluxes

In this study, the crop growth model (CERES3.0) was coupled into the Biosphere-Atmosphere Transfer Scheme (BATS), which is called BATS_CERES, to represent interactions between the land surface and crop growth processes. The effects of crop growth and development on land surface processes were then studied based on numerical simulations using the land surface models. Six sensitivity experiments by BATS show that the land surface fluxes had substantial changes when LAI was changed from 0 to 6 m2/m2. Numerical experiments for Yucheng and Taoyuan stations reveal that the coupled model could capture not only the responses of crop growth and development to environmental conditions, but also the feedbacks to land surface processes. For quantitative evaluating the effects of crop growth and development on surface fluxes in China, two numerical experiments by BATS_CERES (CSM-run) and the original one BATS (CTL-run) conducted over the continental China. Comparison of the two runs shows decreases of leaf area index and fractional vegetation cover when incorporating dynamic crop in land surface simulation, which lead to less canopy interception, vegetation transpiration, total evapotranspiration, top soil moisture, and more soil evaporation, surface runoff, root zone soil moisture. These changes are accompanied by decreasing latent heat flux and increasing sensible heat flux in the cropland region. In addition, the comparison between the simulation and observation proved that incorporating the crop growth and development process into the land surface model could reduce the systematic biases of the simulated leaf area index and top soil moisture, hence improve the simulation of land surface fluxes.