Inverse analysis of the effect of soil vertical heterogeneity on land surface and subsurface processes
Kun Yang (1), Toshio Koike (1), Baisheng Ye (3)
(1) University of Tokyo
(3) Chinese Academy of Science
The importance of soil horizontal heterogeneity has been widely addressed in modeling of land surface processes, but relatively few studies explore the effect of soil vertical heterogeneity on land surface and subsurface processes. It is the motivation of this study to investigate the relationship between the soil vertical heterogeneity and the land processes. For this purpose, a single-source land surface model is developed, which approximates a vertically heterogeneous soil by a homogeneous top domain, a homogeneous deep domain, and a transitional domain between the two. The model parameters of the top and bottom domains are inversely estimated from observed soil moisture and temperature profiles, and then the parameters are reasonably interpolated for the transitional layer. The model parameters include soil domain division, soil hydraulic and thermal parameters, and the surface evaporation resistance.
Analyses are carried out based on synthetic data and data collected in the Tibetan Plateau. We suggest that the soil vertical heterogeneity plays a key role in land surface and subsurface processes. Simulations with uniform soil parameters cannot reproduce observed soil moisture, temperature, and surface energy budget for vertically heterogeneous soils even though all model parameters are optimized. We also find that inversely estimated soil parameters for each domain could be quite different from laboratory analyzed one, because the former represents the mean properties of each soil domain while the latter represents the properties of a small soil sample. Simulations with the latter may produce erroneous soil moisture profiles. Moreover, we emphasize that a successful simulation of soil moisture and temperature profiles is not an adequate condition for correct simulation of the surface energy budget, so a land surface model should be evaluated based on not only comparisons of soil moisture and temperature but also comparisons of energy partitions.
Submittal Information
Name :
Date :
Kun Yang
13-Jul-04-16:04:07
Organization :
Theme :
University of Tokyo
Theme 1
Address :
Presentation :
Department of Civil Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan