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Determination of sensible heat flux over sparse canopy using thermal infrared data

Agricultural and Forest Meteorology

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Abstract

Surface temperatures, Ts, were estimated for a natural vegetative surface in Owens Valley, California, with infrared thermometric observations collected from an aircraft. The region is quite arid and is composed primarily of bushes (???30%) and bare soil (???70%). Application of the bulk transfer equation for the estimation of sensible heat, H, gave unsatisfactory values when compared to Bowen ratio and eddy correlation methods over a particular site. This was attributed to the inability with existing data to properly evaluate the resistance to heat transfer, rah. To obtain appropriate rah-values the added resistance to heat transfer, kB-1, was allowed to vary although there is both theoretical and experimental evidence that kB-1 for vegetative surfaces can be treated as constant. The present data indicate that for partial canopy cover under arid conditions kB-1 may be a function of Ts measured radiometrically. The equation determining kB-1 was simplified and tested over another arid site with good results; however, this had a limited data set (i.e., 6 data points). The dimensionless kB-1 equation is simplified for use over full canopy cover and is shown to give satisfactory estimates of H over a fully-grown wheat crop. ?? 1989.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Determination of sensible heat flux over sparse canopy using thermal infrared data
Series title:
Agricultural and Forest Meteorology
Volume
44
Issue:
3-4
Year Published:
1989
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
197
Last page:
216
Number of Pages:
20