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United States Department of Agriculture

Agricultural Research Service

Title: Estimation of Heat and Momentum Fluxes over Complex Terrain Using a Large Aperture Scintillometer 1360

Authors
item Chehbouni, A. - IRD/IMADES, MEXICO
item Watts, C. - IMADES, MEXICO
item Lagourade, J-P. - INRA, FRANCE
item Kerr, Y. - CESBIO, FRANCE
item Rodriquez, J. - IMADES, MEXICO
item Bonnefond, J-M. - INRA, FRANCE
item Santiago, F. - IMADES, MEXICO
item Dedieu, G. - CESBIO, MEXICO
item Goodrich, David
item Unkrich, Carl

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2000
Publication Date: December 13, 2000

Interpretive Summary: Arid and semi-arid regions account for approximately one-third of the land mass of earth. These regions are experiencing continued pressure from population growth in many parts of the world. Water is a critical resource in these regions and is often in short supply. The amount of energy reaching the earth from the sun and leaving the earth's surface is a very important factor in how much, and how fast, water is evaporated from the earth's surface or transpired through plants and into the surrounding air. Measuring components of this energy over large areas and patches of ground covered by very different vegetation types is very difficult. In this study a new instrument's (a large aperture scintillometer) ability to measure a component of the energy balance is tested in Sonora, Mexico over grass, mesquite, and a complex patch of grass and mesquite. It was found that this instrument can make relatively good measurements over complex land cover types. Instruments of this type are important for verification of energy measurements made over large areas by satellites which will enable better management of water resources in arid/semiarid areas and many other regions around the world.

Technical Abstract: A comprehensive experimental plan has been designed to further investigate the potential and the limitations associated with the use of a large aperture scintillometer (LAS) to infer path average sensible and momentum fluxes over complex surfaces as part of the Semi-Arid Land-Surface- Atmosphere (SALSA) Program. The complexity of the terrain is associated with the type and the cover of the vegetation canopy as well as the change in topography. Scintillometer based estimates of sensible heat flux and friction velocity are compared to those measured be eddy correlation systems over a grassland patch, a mesquite patch, and over a transect spanning both patches. The results show that considering the complexity of the surface, the overall performance of the scintillometer is relatively good.

Last Modified: 11/27/2014
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