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Ocean Surface Topography from Space
Multi sensor air-sea interaction process studies using the satellite altimeter constellation


Douglas Vandemark - (University of New Hampshire, Durham)

Co-Investigator/Co-PI(s) (non-US organization only):
  Dr. Bertrand Chapron
Dr. Jean Tournadre
(University of New Hampshire, Durham)
(University of New Hampshire, Durham)

  Dr. Hui Feng
(University of New Hampshire, Durham)

Understanding of the coupled atmosphere-ocean is being rapidly refined to the point where the time and space scales of weather and climate have begun to converge. Satellite altimetry is most widely known for its measurement of ocean mesoscale sea surface dynamic topography, but accurate and high-resolution altimeter observations of ocean wind and sea state play an increasing important role in global ocean observing system efforts. These data will likely gain emphasis in the coming years with a constellation of 4-6 altimeters providing greater coverage than ever before. This project will focus on ocean surface roughness phenomena that are best addressed using the satellite altimeter and radiometer sensors and then on devising approaches that can exploit these results using past and future altimeter datasets as well as their extension to other microwave ocean sensors in earth orbit. Two studies are proposed. First is a revisit and refinement of the capability of the altimeter to resolve calm-water regions of the ocean their wind stress variability. Nadir-viewing radar altimetry is most sensitive to these conditions andthe high signal-to-noise and sub-km spatial resolution has shown promise to identify surface slicks, rain lenses, and ocean frontal processes. New advanced computational processing now permits improved global characterization of these features, while expanded ocean salinity, rain, and ocean color data coverage can be combined with altimeter constellation data to gain further insight. These data will be merged to conduct investigations that target Pacific warm pool and equatorial upwelling regions where high ocean heat content, diurnal warming, and biogenic slicks are prominent signatures in light wind regions. The second study seeks to demonstrate that the combination of down-looking microwave radiometry and altimetry on the Jason satellite platforms can provide an unambiguous method to isolate the signature of foam on the sea surface that occurs due to wave breaking. Methods here will involve comparisons with global ocean wave modeling and tests of their parameterizations for wave breaking, calibration with ocean wave measurement buoys, and then the extension of study results to off-nadir swath radiometry where daily global coverage becomes feasible. Our team will also support NASA ocean surface topography science team efforts to calibrate and validate new Jason-3 and Sentinel 3 radar altimeter surface measurements as part of this work with the satellite ocean backscatter, sea state, and sea surface height datasets.

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