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 (Keller, 1998). 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 thickness of 0.2-0.3 m. Intensive in situ measurements of the pancake ice in the MIZ some 280 km W of the image location were made from FS Polarstern during a period covering the satellite imaging, and yielded a mean ice thickness of 0.24 m. We conclude that this technique is giving 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 remotely sensing ice thickness in pancake icefields.
Wave dispersion by Antartic pancake ice from SAR images: a method for measuring ice thickness
Giacomo De Carolis
2006
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 (Keller, 1998). 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 thickness of 0.2-0.3 m. Intensive in situ measurements of the pancake ice in the MIZ some 280 km W of the image location were made from FS Polarstern during a period covering the satellite imaging, and yielded a mean ice thickness of 0.24 m. We conclude that this technique is giving 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 remotely sensing ice thickness in pancake icefields.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
