HR: 09:00h
AN: C21B-05 INVITED     [Abstracts]
TI: ICESat Observations of Inland Surface Water Stage, Slope, and Extent: a new Method for Hydrologic Monitoring
AU: * Harding, D J
EM: david.j.harding@nasa.gov
AF: NASA Goddard Space Flight Center, Mail Code 921, Greenbelt, MD 20771 United States
AU: Jasinski, M F
EM: michael.f.jasinski@nasa.gov
AF: NASA Goddard Space Flight Center, Mail Code 974, 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 540 million laser pulse observations of ice sheet, ocean surface, land topography, and inland water elevations and cloud and aerosol height distributions. The ICESat mission has demonstrated the following laser altimeter capabilities relevant to observations of inland water: (1) elevation precision of 2 to 3 cm, suitable for detecting river surface slopes along long river reaches or between multiple crossings of a channel, (2) decimeter single pulse absolute elevation accuracy for flat surfaces and clear atmosphere, suitable for detection of stage changes, (3) detection of water surface elevations beneath vegetation canopies, suitable for measuring water stage in flooded forests, (4) precise spacecraft pointing so as to position the laser profile on the Earth's surface with an accuracy of 50 m (1 sigma), enabling small water bodies to be targeted and re-observed through time, (5) adequate signal levels from quasi-specular water surfaces up to 5ø off-nadir, enabling access to any location on the Earth's surface from the ICESat repeat orbit, and (6) day and night operation with successful laser ranging to the Earth's surface through thin to moderate cloud cover, enabling more frequent measurements than can be achieved by passive optical sensors. Here we illustrate these capabilities by showing ICESat observations through time for selected river and lake locations and discuss their implications for estimating discharge and storage changes.
DE: 1836 Hydrologic budget (1655)
DE: 1894 Instruments and techniques
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting