|Diak, George - UNIV OF WISC, WISCONSIN|
|Norman, John - UNIV OF WISC, WISCONSIN|
Submitted to: Water Science
Publication Type: Book / Chapter
Publication Acceptance Date: July 25, 2000
Publication Date: N/A
Technical Abstract: Satellite-based surface radiometric temperatures can serve as a key lower boundary condition, defining the degree to which available surface net radiation is partitioned between sensible and latent heat fluxes. For regional scale applications, a serious problem is deriving the required meteorological upper boundary conditions for each satellite pixel. Models using surface-air temperature differences are highly susceptible to uncertainties in air temperature. Recently, this limitation has been addressed through an energy closure scheme (ALEXI) that uses the growth of the atmospheric boundary layer (ABL), a quantity sensitive to heat flux input to the lower atmosphere, and coupling this growth to the temporal changes in surface radiometric temperature (Anderson et al, 1997 and Mecikalski et al., 1999). Another simpler scheme uses the time rate of change in radiometric temperature and air temperature observations (dual temperature difference approach) from a nearby weather station in a simple formulation for computing regional heat fluxes (Norman et al, 1999). By using a time difference in air temperature errors caused by using local shelter level observations for representing a region are reduced. The utility of the dual temperature difference approach is evaluated at the field scale with ground-based radiometric temperature observations and regional weather station data in a semiarid region. In addition, a comparison of regional scale heat fluxes between the more rigorous ALEXI model and the simple dual temperature difference method using satellite data over the Southern Great Plains is presented.