HR: 16:15h
AN: G14A-04    [Abstracts]
TI: Hydrological applications of ICESat/GLAS
AU: * Schutz, B
EM: schutz@csr.utexas.edu
AF: University of Texas Center for Space Research, 3925 W. Braker, Suite 200, Austin, TX 78759 United States
AU: Urban, T
EM: urban@csr.utexas.edu
AF: University of Texas Center for Space Research, 3925 W. Braker, Suite 200, Austin, TX 78759 United States
AB: A new spaceborne geodetic tool was placed into a 600 km, near polar Earth orbit in January 2003. Although the laser altimeter carried on ICESat, known as the Geoscience Laser Altimeter System (GLAS), was designed to generate high accuracy profiles of the polar ice sheets to enable detection of surface change, many other applications of the instrument have been demonstrated, such as land topography, atmospheric characteristics, vegetation canopy height, and hydrology. With a laser pulse repetition rate of 40 Hz and a 70-meter laser footprint on the surface, successive illuminated laser spots (footprints) are separated on the surface by 170 meters. The GLAS instrument has been shown to produce an altitude measurement of 2-3 cm precision, depending on the surface characteristics within the illuminated laser footprint. ICESat instrumentation enables determination of the direction of the laser pulse, which in turn supports the determination of the geodetic location of the laser footprint centroid (geodetic latitude, longitude and ellipsoidal height). A variety of tests have been applied to validate the accuracy of the resulting laser altimeter surface profiles. Current accuracy estimates of the laser footprint location are decimeter level in geodetic height and 15 meters in horizontal position (latitude/longitude). The agile satellite allows pointing the laser at targets of opportunity as well. The global surface water level observations made by GLAS have broad application due to a very high spatial resolution compared to traditional radar altimetry and especially in remote regions. Using a variety of examples from rivers, lakes, wetlands, and coastal applications, the performance of the GLAS instrument will be illustrated. With the current demonstrated accuracy, it is evident that the laser profiles can serve as geodetic control points for other instrumentation and as constraints for modeling. With ongoing calibration/validation efforts, the performance is expected to improve, allowing GLAS to accurately monitor seasonal and long-term elevation and spatial changes of surface waters.
DE: 1200 GEODESY AND GRAVITY
DE: 1600 GLOBAL CHANGE (New category)
DE: 1800 HYDROLOGY
DE: 1894 Instruments and techniques
DE: 4500 OCEANOGRAPHY: PHYSICAL
SC: Geodesy [G]
MN: 2005 Joint Assembly