Studies On The Influence Of Soil Hydrological Characteristics On Land Surface Process

Four soil hydraulic models are chosen and their characteristics , abilities and practicability on simulation of soil moisture for different soil types and soil moisture conditions are validated against two dataset observed at Gaize (located at west region of Tibet Plateau) and Feixi (Anhui province).In order to examine the influence of soil hydraulic characteristics on land Surface process, the four soil hydraulic models are coupled with the Simplified Simple Biosphere Model (SSiB) respectively and the simulated net radiation, sensible heat, latent heat and soil heat fluxes by the four coupled model are compared. In this study, the SSiB model is coupled with MM5 and the coupled model is validated against Huanan rainstorm (June 8 to 9, 1998) dataset observed in 1998. The results obtained by the coupled model with different soil hydraulic models are compared for evaluating the significance of soil hydraulic characteristics in short time precipitation simulation. To explore the importance of soil moisture on land- atmosphere heat and water exchange, the impact of soil moisture on reflectivity and associated aspects of land surface modeling are also examined.The results in this study can be summarized by the following:(1) Some difference of calculated soil hydraulic conductivity and soil matric potential are existed in different soil hydraulic models. These divergences exert the influence on simulated results of land surface model by influencing soil hydraulic characteristics.(2) The performance of land surface model is sensitive to the choice of soil hydraulic models. The diminutive deviate of soil moisture estimated by different hydraulic models affect the land surface netradiation by affecting soil reflectance, and farther affect sensible heat, latent heat and soil heat fluxes. So it is important not only to choice appropriate soil hydraulic models, but also to consider the soil moisture- reflectance relationships in land surface model. (3) The coupled SSiB/ MM5 model test results show that the performance of SSiB/ MM5 model in not sensitive to the choice of soil hydraulic models for short- time precipitation simulation.