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Proceedings Paper

Comparison of aerodynamic and radiometric surface temperature using precision weighing lysimeters
Author(s): Paul D. Colaizzi; Steven R. Evett; Terry A. Howell; Judy A. Tolk
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Paper Abstract

Radiometric surface temperature (Ts) is commonly used as a surrogate for aerodynamic temperature (To) in computing the sensible heat flux term (H) in the energy balance. However, these temperatures may differ by several degrees, leading to possible errors (especially for large H) and their relationship is not well known. Previous researchers have established empirical and semi-empirical parameterizations of the radiometric roughness length (zor) or some related form (e.g., kBr−1 = ln[zom/zor], where zom is the momentum roughness length). In this paper, we estimated To - Ta (where Ta is air temperature at 2 m height) and zor using large, precision weighing lysimeters planted with irrigated alfalfa, irrigated and dryland cotton, and dryland grain sorghum. Ts was measured by infrared thermometers mounted over the lysimeters. No apparent relations were found between (To − Ta) and (Ts - Ta) or between zor (in the kBr−1 form) and meteorological variables or leaf area index (LAI). The kBr−1 parameter appeared to be most influenced by the different surface roughness of each crop type. Using constant kBr-1 values established for each type of surface, the energy balance model showed reasonable agreement with H and LE derived from lysimeter measurements.

Paper Details

Date Published: 9 November 2004
PDF: 15 pages
Proc. SPIE 5544, Remote Sensing and Modeling of Ecosystems for Sustainability, (9 November 2004); doi: 10.1117/12.559503
Show Author Affiliations
Paul D. Colaizzi, USDA Agricultural Research Service (United States)
Steven R. Evett, USDA Agricultural Research Service (United States)
Terry A. Howell, USDA Agricultural Research Service (United States)
Judy A. Tolk, USDA Agricultural Research Service (United States)

Published in SPIE Proceedings Vol. 5544:
Remote Sensing and Modeling of Ecosystems for Sustainability
Wei Gao; David R. Shaw, Editor(s)

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