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ARS Home » Research » Publications at this Location » Publication #131331
Title: QUANTITATIVE ESTIMATES OF EMISSIVITY USING ASTER DATA

Author
item Schmugge, Thomas
item French, Andrew
item JACOB, FREDERIC - VISITING SCIENTIST HRSL
item OGAWA, KENTA - HITACHI LTD

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2002
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 to estimate surface fluxes using remote sensing data. One way to distinguish these models is the decoupling or not of soil and vegetation components, which lead to label "one layer" or "two layers" models. This difference yields different approaches for computing surface radiative properties, surface aerodynamic properties and energy balance components. The objective of this study is to compare 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 sensor 90 m spatial resolution reduces problems due to mixed pixels when assessing both model differences and performances. ASTER scenes acquired at different seasons were used in the comparison that includes numerous land use and meteorological situations. The considered models are the one layer SEBAL model and the two layered Tw Source Energy Balance (TSEB) model. SEBAL presents uses information 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. The estimates from the two models are validated against field measurements.