Polar Marine Gravity

Polar Marine Gravity Fields from the ERS-1 GM mission

Arctic Southern Ocean

Click on the thumbnails for high resolution GIF images.

This work is done in collaboration with Dr. Seymour Laxon of University College London, Mullard Space Science Laboratory; it involves the derivation of marine gravity from satellite altimetry over permanently ice-covered polar seas.

Antarctic Marine Gravity (Southern Ocean)

A high-resolution gravity field covering all of the Southern Ocean has been derived using ERS-1 data including ERS-1 geodetic phase, wave-form data. This field encompasses areas which are seasonally - as well as areas which are perpetually - covered by sea ice. Permanent sea-ice cover has precluded exploration of large areas of the Southern Ocean. This new gravity map permits us to view tectonic details imprinted in the ocean floor such as gravity lineations, which are the expression of fracture zones left by early (65 to 83 million years ago) Pacific-Antarctic sea-floor spreading that separated the Campbell Plateau and New Zealand continent from West Antarctica. These lineations constrain plate motion history and confirm the hypothesis that the Marie Byrd Land portion of Antarctica behaved as two distinct plates prior to 65 million years ago.

For details see an article by McAdoo and Laxon in the April 25, 1997 issue of Science, volume 276, pp 556-561,

Arctic Ocean Gravity

This image shows the marine gravity field over the Arctic Ocean as determined using satellite altimetry acquire from ERS-1 over seas which are perpetually ice-covered . Previously data over ice covered regions has been excluded due to contamination by sea ice. By reprocessing the data at MSSL we have retreived these data to reveal both known and unknown features on the floor of the Arctic Ocean. The new discoveries include an extinct spreading ridge in the ocean basin north of Canada revealing for the first time, the origin of a large part of the Arctic Basin, a result of major geophysical significance.

For details see an article by Laxon and McAdoo in the July 29, 1994 issue of Science, volume 265, pp 621-624,

For more information contact Dave McAdoo at dave@comet.grdl.noaa.gov or Seymour Laxon at swl@mssls3.mssl.ucl.ac.uk.

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