Validation and sensitivity analysis of a new atmosphere-soil-vegetation model. part II: impacts on in-canopy latent heat flux over a winter wheat field determined by detailed calculation of canopy radiation transmission and stomatal resistance

摘要

This paper describes the validation and sensitivity analysis of an atmosphere-soil-vegetation model. The model consists of one-dimensional multilayer submodels for the atmosphere, soil, and vegetation and a radiation scheme for the transmission of solar and longwave radiation in the canopy. The model framework was validated by the comparison of ground surface heat fluxes between calculations and observations in the previous paper. In this study the radiation scheme is modified to calculate the foursolar radiation components (visible and nearinfrared bands in direct and diffuse components) separately. By this modification, the observed albedo is simulated more properly than before. This modification also enables the utilization of a more realisticstomatal resistance scheme that considers the spectral band of solar radiation: visible or photosynthetically active radiation. The impacts of the more realistic calculations for radiation transmission in the canopy and stomatal resistance on the calculations of latent heat flux in a short canopy are examined. As affected by the changes of the radiation and stomatal resistance schemes, errors in the latent heat flux calculation by the former model were improved by the modified model, which indicates the importance of the detailed calculation of the canopy radiation transmission and the stomatal resistance.