Submitted to: European Geophysical Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2003
Publication Date: N/A
Technical Abstract: The reliability of ASTER-based surface heat flux estimates is investigated using high resolution observations (12 meters) in a series of data aggregation experiments. Aircraft data are combined with surface observations and a two-source surface energy flux model to create heat flux estimates at 12 meter resolutions. Surface heat flux estimates at coarser resolutions are then simulated in two ways. In one approach, the flux estimates are averaged. In the other, the original observed radiances are averaged to create simulated observations at coarser scales, which are then transformed into surface energy fluxes. Both approaches are physically meaningful, but because of modeling non-linearities, might not result in similar energy flux estimates. When the aggregation experiments were performed using data from two sites-- El Reno, Oklahoma, USA (1997) and Jornada Experimental Range, New Mexico, USA (1999)-- the differences in flux estimates were found to be sensitive to relative scales of landscape heterogeneity and image resolution. 90 meter surface flux estimates, when directly aggregated from higher resolution flux estimates (4-12 meters), agreed reasonably with tower-based eddy correlation measurements. But 90 meter flux estimates derived from aggregated observations tended to exaggerate extreme values. When the high resolution observations are smoothed over short distances (12-36 meters), the simulated 90 meter observations agreed reasonably with the aggregated 90 meter fluxes.