HR: 09:15h
AN: C21B-06    [Abstracts]
TI: ICESat Validation of SRTM C-Band Digital Elevation Models
AU: * Carabajal, C C
EM: claudia@bowie.gsfc.nasa.gov
AF: Claudia C. Carabajal, NVI, Inc.@NASA/GSFC Space Geodesy Branch - Code 926, Greenbelt, MD 20771 United States
AU: Harding, D J
EM: David.J.Harding@nasa.gov
AF: David J. Harding, NASA/GSFC Geodynamics Branch - Code 921, Greenbelt, MD 20771 United States
AB: Understanding the quality of the DEM data sets is crucial to their use in land process studies and in detection of change obtained from comparison of DEMs acquired at different times. Elevation data from the Geoscience Laser Altimeter System (GLAS) on board the Ice Cloud and Land Elevation Satellite (ICESat) provides a globally distributed data set that can be used to independently estimate the accuracy of available Digital Elevation Models (DEMs), such as the ones produced by the Shuttle Radar Topography Mission (SRTM). Calibration and validation activities indicate that the accuracy of the best ICESat data is currently approximately 30 m horizontal and 50 cm vertical (1 sigma for 1 degree laser beam incidence angle on the Earth's surface), with further improvements expected from ongoing calibration efforts. The current accuracy is of sufficient quality for assessment of the SRTM DEMs. Our efforts have concentrated on documenting elevation differences between ICESat and SRTM C-band elevations for various regions of the world with variable topography and vegetation cover. ICESat data enables the estimation of radar phase center elevation biases in vegetated regions with respect to the top of the canopy and ground. Errors in the SRTM elevations data are quantified based on the distribution of the ICESat to SRTM elevation differences, and their relationship with local relief and land-cover characteristics. Correlations between ICESat to SRTM elevation differences and waveform extent, a surrogate for canopy height, and canopy closure are also examined. Regional analyses, previously conducted in the Western US, Alaska and the central Amazon Basin, have been expanded and now include data from all the continents (except Antarctica which lacks SRTM coverage). Based on the results of this work, the ICESat data product for each laser footprint location will include the elevation from the SRTM 90 m resolution product where available, facilitating global analyses using these complimentary elevation measurement systems.
DE: 1694 Instruments and techniques
DE: 1699 General or miscellaneous
DE: 1294 Instruments and techniques
DE: 1640 Remote sensing
DE: 1645 Solid Earth
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting