HR: 1330h
AN: H23B-02    [Abstracts]
TI: Validating Patterns in Large Scale Sensible and Latent Heat Flux Estimates from a Remote Sensing-based Model and Aircraft-based Flux Measurements
AU: * Kustas, W P
EM: bkustas@hydrolab.arsusda.gov
AF: USDA-ARS Hydrology and Remote Sensing Lab, Bldg 007 BARC-West, Beltsville, MD 20705
AU: Anderson, M C
EM: mcanders@wisc.edu
AF: USDA-ARS Hydrology and Remote Sensing Lab, Bldg 007 BARC-West, Beltsville, MD 20705
AU: Anderson, M C
EM: mcanders@wisc.edu
AF: Department of Soil Science, University of Wisconsin , Madison, WI
AB: A remote sensing field experiment conducted in the Southern Great Plains in 1997 (SGP97) in central Oklahoma, had aircraft-based flux observations as well as remotely sensed data collected over one of the main study sites in central Oklahoma. This agricultural region contains primarily grassland/pasture and winter wheat, which was recently harvested leaving a significant number of fields either as wheat stubble or plowed bare soil. Multi-spectral data obtained by aircraft provided high resolution (30 m) spatially-distributed vegetation cover and surface temperature information over an area approximately 10 km north-south by 30 km east-west. The spatial variations in these surface states strongly affect the partitioning of surface fluxes between sensible and latent heat. These data, together with coarser resolution (5 km) satellite data, are used in a remote sensing-based energy balance modeling system that disaggregates flux estimates to the 30 m resolution. From the aircraft-based measurements collected along the 15 km transect, "segmented" flux values over 1 km sampling intervals were computed, which were then sub-sampled using a 250 m moving window using a new scheme for estimating time-space dependence of aircraft surface fluxes. From these two estimates of the large scale heat flux patterns, a comparison is made for exploring consistency in flux distributions. This type of comparison involves estimation of the flux-footprint or source area for the aircraft flux observations in order to weight the upwind model pixels within the aircraft sensor footprint. Highest correlation between aircraft and modeled estimated heat and water vapor fluxes were obtained using different flux-footprint estimates with the source-area for heat estimated to be much closer to the aircraft flight line than for water vapor. Factors that may be contributing to these results are discussed.
DE: 1818 Evapotranspiration
DE: 3307 Boundary layer processes
DE: 3360 Remote sensing
DE: 3379 Turbulence
SC: Hydrology [H]
MN: 2005 Joint Assembly