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ARS Home » Pacific West Area » Tucson, Arizona » SWRC » Research » Publications at this Location » Publication #87188


item SCOTT, R.
item Goodrich, David - Dave
item LHOMME, J.
item QI, J.
item KERR, Y.

Submitted to: American Meteorological Society
Publication Type: Proceedings
Publication Acceptance Date: 1/21/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Temperatures on and over the land surface are important in determining how much water is evaporated from soils and plants to the atmosphere. Although the relationship between these energy terms has been investigated for many years on land with uniform plant cover, little is known about the relationship on land with mixed cover. As part of the Semi-Arid Land-Surfac cat two sites, one grass dominated and one shrub dominated, on the San Pedr River, east of Sierra vista, Arizona. Each of the sites was instrumented with tower-mounted meteorological sensors to measure air temperature, wind speed, incoming solar radiation and other factors. The researchers found that temperature relationships for the grassy area and the woody area were similar. This finding, if confirmed by subsequent analysis, will allow for the development of a single equation to estimate heat changes over complex vegetation in semi-arid areas.

Technical Abstract: Thermal infrared remotely sensed surface temperature has been widely used in operational models to evaluate the spatial distribution of the energy balance components. Most past investigations comparing aerodynamic and radiative surface temperatures have been conducted in sparse but homogeneous vegetated surfaces. The present study, conducted as part of the eSALSA global change research program, examined these properties on heterogeneous surfaces on grass and shrub covered plots within the Upper San Pedro Basin, in southeastern Arizona. Each of the two sites was instrumented with tower-mounted meteorological sensors to measure air temperature, relative humidity, wind speed, incoming solar radiation, air pressure, and precipitation, as well as the Bowen ratio and infrared temperature of the surface. Data over each site were used to examine the differences between radiative and aerodynamic temperatures for several days sinclusive of a Landsat-TM overpass. The results indicated that the relationship between aerodynamic, radiative and air temperature also valid over a surface made up of two distinct patches. Additional analysis and validation will be conducted confirm the relationships suggested in this study.