SAR imaging of wave dispersion in Antarctic pancake ice and its use in measuring ice thickness

Abstract

A synthetic aperture radar (SAR) image of the advancing winter marginal ice zone (MIZ) in the Antarctic, composed of frazil‐pancake ice, has been analysed in a new way in order to test the predictions of a recently developed theory of wave dispersion in pancake ice which treats the ice as a viscous layer. In the image, obtained in April 2000, the structure of the wave spectrum in the MIZ and its change from the open‐water spectrum are consistent with a pancake layer 24 cm thick. Intensive in situ measurements of the pancake ice in the MIZ 280 km W of the image location were made from FS Polarstern during a period covering the satellite imaging, and also yielded a mean ice thickness of 24 cm. We conclude that this technique gives realistic results for ice thickness, whereas earlier work based on a different dispersion theory (mass loading) tended to over‐estimate thickness. After further validation, it is therefore possible that the SAR wave technique can become an accepted method for monitoring ice thickness in pancake icefields.