Estimates of ocean wave heights and attenuation in sea ice using the SAR wave mode on Sentinel-1A

• Published in: Geophysical Research Letters
• Main Authors: Ardhuin, Fabrice, Collard, Fabrice, Chapron, Bertrand, Ardhuin, Fanny, Guitton, Gilles, Mouche, Alexis, Stopa, Justin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2015
• Subjects: ocean waves; SAR; sea ice; ice pack; Sea ice
• Online Access: https://archimer.ifremer.fr/doc/00256/36718/35332.pdf; https://doi.org/10.1002/2014GL062940; https://archimer.ifremer.fr/doc/00256/36718/

Swell evolution from the open ocean into sea ice is poorly understood, in particular the amplitude attenuation expected from scattering and dissipation. New synthetic aperture radar (SAR) data from Sentinel-1A wave mode reveal intriguing patterns of bright oscillating lines shaped like instant noodles. We investigate cases in which the oscillations are in the azimuth direction, around a straight line in the range direction. This observation is interpreted as the distortion by the SAR processing of crests from a first swell, due to the presence of a second swell. Since deviations from a straight line should be proportional to the orbital velocity toward the satellite, swell height can be estimated, from 1.5 to 5 m in the present case. The evolution of this 13 s period swell across the ice pack is consistent with an exponential attenuation on a length scale of 200 km.