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Title: COMPARISON OF SURFACE ENERGY BALANCE MODELS USING ASTER DATA

Author
item JACOB, FREDERIC - PRIVATE CONSULTANT
item French, Andrew
item Schmugge, Thomas

Submitted to: International Symposium on Recent Advances in Quantitative Remote Sensing
Publication Type: Proceedings
Publication Acceptance Date: 7/3/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The knowledge of surface fluxes is of prime interest in agronomy, meteorology and hydrology. Several models have been developed recently to estimate surface fluxes using remote sensing data. A possible way to distinguish these models is the decoupling or not of soil and vegetation components, which lead to label "one layer" or "two layer" models. Considering separate soil and vegetation components or not requires different approaches when computing surface radiative properties, surface aerodynamic properties and energy balance components. The considered assumptions are more or less robust, which induces advantages and drawbacks for each of the "one layer" and "two layers" methods. This study aims at comparing these two approaches using ASTER data acquired over both the Jornada semiarid rangeland (New Mexico, USA) and the El Reno grazing lands (Oklahoma, USA). The 90 m spatial resolution of this sensor reduces problems due to mixed pixels when assessing both model differences and performances. We considered several ASTER scenes acquired at different seasons to perform a comparison that includes numerous land use and micrometeorological situations. The considered models are the one layer SEBAL model and the two layers TSEB model. SEBAL presents the interest to use informations contained in the spatial variability of convective fluxes that results from hydrological contrasts. TSEB is a more robust tool when describing sparse vegetation since the spatial variability is better reproduced by decoupling soil and vegetation components. The comparison is performed over several variables that are computed in different ways: albedo, roughness lengths for momentum and heat, air temperature, wind speed, soil heat flux, and of course convective fluxes. This allows the assessment of the robustness of the assumptions used by one of the two models when comparing with well validated approaches used by the other. Finally, the estimates are validated against field measurements.