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The Southern Ocean Waves Experiment. Part III: Sea Surface Slope Statistics and Near-Nadir Remote Sensing

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  • 1 Code 614.6, NASA Goddard Space Flight Center, Wallops Island, Virginia
  • | 2 School of Mathematics, The University of New South Wales, Sydney, New South Wales, Australia
  • | 3 Ocean Process Analysis Laboratory, University of New Hampshire, Durham, New Hampshire
  • | 4 Departement d’Oceanographie Spatiale, Institut Français du Petrole, Plouzané, France
  • | 5 Research Aircraft Facility, National Center for Atmospheric Research, Broomfield, Colorado
  • | 6 CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia
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Abstract

During the Southern Ocean Waves Experiment (SOWEX), registered ocean wave topography and backscattered power data at Ka band (36 GHz) were collected with the NASA Scanning Radar Altimeter (SRA) off the coast of Tasmania under a wide range of wind and sea conditions, from quiescent to gale-force winds with 9-m significant wave height. Collection altitude varied from 35 m to over 1 km, allowing determination of the sea surface mean square slope (mss), the directional wave spectrum, and the detailed variation of backscattered power with incidence angle, which deviated from a simple Gaussian scattering model. The non-Gaussian characteristics of the backscatter increased systematically with the mss, suggesting that a global model to characterize Ka-band radar backscatter from the sea surface within 25° of nadir might be possible.

++ On assignment for NASA at the NOAA/Earth System Research Laboratory, Boulder, Colorado

Corresponding author address: E. J. Walsh, NOAA/Earth System Research Laboratory, PSD3 325 Broadway, Boulder, CO 80305-3337. Email: edward.walsh@nasa.gov

Abstract

During the Southern Ocean Waves Experiment (SOWEX), registered ocean wave topography and backscattered power data at Ka band (36 GHz) were collected with the NASA Scanning Radar Altimeter (SRA) off the coast of Tasmania under a wide range of wind and sea conditions, from quiescent to gale-force winds with 9-m significant wave height. Collection altitude varied from 35 m to over 1 km, allowing determination of the sea surface mean square slope (mss), the directional wave spectrum, and the detailed variation of backscattered power with incidence angle, which deviated from a simple Gaussian scattering model. The non-Gaussian characteristics of the backscatter increased systematically with the mss, suggesting that a global model to characterize Ka-band radar backscatter from the sea surface within 25° of nadir might be possible.

++ On assignment for NASA at the NOAA/Earth System Research Laboratory, Boulder, Colorado

Corresponding author address: E. J. Walsh, NOAA/Earth System Research Laboratory, PSD3 325 Broadway, Boulder, CO 80305-3337. Email: edward.walsh@nasa.gov

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