HR: 12:05h
AN: C22A-08    [Abstracts]
TI: Ocean Elevation and Wave Heights from GLAS
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
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
AB: The Geoscience Laser Altimeter System (GLAS) was designed to range to ice, land and atmosphere, but measures ocean surfaces as well. The footprints of the laser (70 m diameter, 170 m spacing, 40 Hz temporal resolution) contrast sharply with traditional radar altimetry (6-8 km diameter, 6-7 km spacing, 1 Hz temporal resolution). Consequently, the two systems observe different ocean phenomena. For calibration, laser and radar data can be similarly compared to each other with the application of ~1-Hz smoothing to GLAS data. The relative ocean height biases between GLAS, Topex, and Jason-1 are estimated using dual-satellite crossovers, along-track analyses, and by comparing to a common Mean Sea Surface (MSS). The Root-Mean-Square (RMS) statistics of these height comparisons, as well as internal crossover statistics, provide a measure of the relative precision of these biases and the current performance of the GLAS data collection campaigns. These relative biases and precisions are compared over global ocean surfaces and are subdivided into groups considering pass direction and local solar time. Ocean waves manifest themselves in the radar waveform as a slope on the leading and trailing edges, which are used to estimate Significant Wave Height (SWH) and sigma0 (wind speed). The wave relationships used for radar altimetry are reexamined for the very different laser altimeter geometry. Comparisons are made between GLAS, Topex, and Jason-1 of SWH, mesoscale variability, and other parameters.
DE: 9805 Instruments useful in three or more fields
DE: 4500 OCEANOGRAPHY: PHYSICAL
DE: 4556 Sea level variations
DE: 4560 Surface waves and tides (1255)
DE: 4594 Instruments and techniques
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting