Day-24: Energy Balance Model for Infrared Scene Generation

Report No. ARL-TR-2672
Authors: Robert A. Sutherland
Date/Pages: April 2002; 47 pages
Abstract: We expand and modify the Rachele-Tunick ?energy balance? concept to include infrared thermal scenes and dynamic effects over time periods of several diurnal cycles. The model requires an initial starting ?IR image? in the form of a two-dimensional temperature array of the scene (generated either synthetically or from real data) plus four corresponding land-use maps describing, (1) surface shortwave reflectivity, (2) longwave emissivity, (3) vegetation type, and (4) subsurface thermal conductivity, some of which can also be generated from empirical models. Meteorological inputs are required at only one key location inside the scene area. These inputs include air temperature, wind speed, relative humidity, cloud cover, and subsurface ?deep soil? temperature. Incoming shortwave solar/sky radiation and longwave sky radiation are optional inputs. Comparisons with data from field experiments indicate that the simple static, or equilibrium, energy balance model does a surprisingly reasonable job of modeling surface temperature despite some obvious conceptual shortcomings which we address using the more rigorous time dependent formulation.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2002