HR: 1340h
AN: C33B-0344    [Abstracts]
TI: Validation of GLAS range measurement over the salar de Uyuni, Bolivia
AU: * Fricker, H A
EM: hafricker@ucsd.edu
AF: Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Borsa, A A
EM: aborsa@ucsd.edu
AF: Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Minster, J B
EM: jbminster@ucsd.edu
AF: Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Bills, B G
EM: bbills@ucsd.edu
AF: NASA/GSFC, Geodynamics Branch, Greenbelt, MD 20771 United States
AU: Carabajal, C
EM: claudia@stokes.gsfc.nasa.gov
AF: NVI, Inc. @ NASA/GSFC, Code 926 - Space Geodesy Branch, Greenbelt, MD 20771 United States
AU: Quinn, K
EM: katy.quinn@jpl.nasa.gov
AF: Jet Propulsion Laboratory/Caltech, Mail Stop 238-332, Pasadena, CA 91109 United States
AB: NASA's Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satellite (ICESat) is Earth's first polar-orbiting satellite laser altimeter. Its primary purpose is to measure ice sheet elevation change, with a scientific requirement of detecting changes as low as 1.5 cm/year. This goal requires precise calibration and validation of the instrument. One approach for validating the GLAS range measurement involves comparison with a land reference target. Dry salt lakes are ideal for this purpose since they are large, stable, easily surveyed using kinematic GPS, and have albedos similar to that of ice. We selected the largest dry salt lake in the world, the salar de Uyuni in Bolivia, as a reference target for GLAS. In September 2002 we surveyed a 54 x 45 km area of the salar with car-mounted kinematic GPS. The resulting DEM of the surface has an estimated precision of 1 cm (RMS) with a total topographic range of less than 1 meter over the survey area. To date there have been six ICESat passes across our surveyed area, along two intersecting tracks. The first two passes occurred during "Laser 2A" operation (September to November 2003), the second two during "Laser 2B" operation (February to March 2004), and the final two during "Laser 2C" (June to July 2004). We compare GLAS elevation measurements from all six passes with the salar de Uyuni DEM, showing how differing atmospheric and surface conditions affected the performance of the GLAS instrument from pass to pass and providing estimates of the relative and absolute accuracies of the range measurement. As an independent check, we compare GLAS elevation profiles with the TOPEX-derived mean sea-surface for ocean areas along the orbits used in the GPS comparison above.
DE: 1694 Instruments and techniques
DE: 1827 Glaciology (1863)
DE: 1640 Remote sensing
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting