HR: 16:30h
AN: G14A-05 INVITED     [Abstracts]
TI: ICESat Observations of Mississippi River Stage and Slope Changes
AU: * Harding, D
EM: david.j.harding@nasa.gov
AF: NASA Goddard Space Flight Center, Mail Code 698, Greenbelt, MD 20771 United States
AB: River discharge and changes in lake, reservoir and wetland water storage are critical terms in the global surface water balance, yet they are poorly observed globally and the prospects for adequate observations from in-situ networks are poor (Alsdorf et al., 2003). The NASA-sponsored Surface Water Working Group has established a framework for advancing satellite observations of river discharge and water storage changes which focuses on obtaining measurements of water surface height (stage), slope, and extent. Satellite laser altimetry provides a method to obtain these inland water parameters and contribute to global water balance monitoring. Since its launch in January, 2003, the Ice, Cloud, and land Elevation Satellite (ICESat), a NASA Earth Observing System mission, has achieved over 650 million laser pulse observations of ice sheet, ocean surface, land topography, and inland water elevations and cloud and aerosol height distributions. ICESat carries the Geoscience Laser Altimeter System (GLAS) that obtains elevation measurements from 80 m diameter footprints spaced 175 m apart along profiles. For surfaces of low slope, single-footprint absolute elevation and horizontal accuracies of 10 cm and 6 m (1 sigma), respectively, referenced to the ITRF 2002 TOPEX/Poseidon ellipsoid are being obtained. Precisely repeated profiles of the Mississippi River from Vicksburg, MS to the confluence with the Arkansas River have been acquired to evaluate ICESat's recovery of river stage and slope. Cloud-free profiles collected on three dates in 2003 and 2004 document river stage and slope measurement precision of 10 cm and 1 cm per km, respectively, at and between crossings of channel meanders. Changes in ICESat-derived stage, average slope of the reach, and local slopes between meander crossings are observed between the three profiles, and the stage changes correlate with in-situ gage measurements. Implications for satellite laser altimeter estimation of river discharge will be discussed.
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
DE: 1836 Hydrologic budget (1655)
DE: 1860 Runoff and streamflow
DE: 1894 Instruments and techniques
SC: Geodesy [G]
MN: 2005 Joint Assembly