Impact of Pixel Size on Mapping Surface Water in Subsolar Imagery
Vern
C
Vanderbilt, NASA Ames Research Center, Vern.C.Vanderbilt@nasa.gov
(Presenting)
Shruti
Khanna, University of California Davis, shrkhanna@ucdavis.edu
Susan
L.
Ustin, University of California Davis, susan@cstars.ucdavis.edu
We observed surface water in a wetland, imaging in the subsolar or specular direction the exceptionally bright specular reflection of sunlight at a ground resolution of 0.3 m. We then simulated ground resolutions between 1.7 m and 1.2 km through aggregation of the 0.3 m pixels.
Contrary to expectations, for these data, the accuracy of spectral mixture analysis (SMA) estimates of surface water increases as pixel ground footprint size increases. Our results suggest that regional to global scale assessments of flooded landscapes and wetlands that do not involve issues requiring one meter resolution per se may be addressed with acceptable accuracy by applying SMA techniques to low resolution imagery.
Our results indicate within-pixel estimates of surface water area derived from data measured by subsolar viewing sensors with large ground pixel footprints, such as satellite POLarization and Directionality of Earth Radiance (POLDER) data, may be highly accurate under moderate surface wind conditions.