Measuring wave heights in sea ice from space: it works!

Mapping wave heights with radar imagery over sea ice has just been demonstrated by a LOPS-led team, thanks to the support of the "Sea State" scientific cruise in the Beaufort sea. These results have been published in the journal "Remote Sensing of Environment".

The technique extends our existing capability to measure waves in the ocean (see e.g. http://oceanwavesremotesensing.ifremer.fr ) to regions covered by sea ice. In fact, it is much easier to measure waves in the presence of ice because the high frequency waves are strongly dissipated in that case, making the transformation of the wave pattern into a radar image much more simple. In fact, it is possible to make a detailed map of the wave-induced velocities in the ice, whereas it was only possible to measure a wave spectrum in the open ocean. It may thus be possible to measure individual wave heights, including freak waves, in the ice.

Further work is underway to process the full archive of images acquired in sea ice by the pair of satellites Sentinel 1A and 1B (5000 or more are adding up every month), and obtain more in situ data to verify the properties of the radar measurements.  Sentinel 1A and 1B are now providing much more wave measurements in the ice than we ever had, allowing detailed investigation of the dissipation rates of waves in the ice, which is related to the pushing of the ice edge by waves. The new technique will thus provide a unique dataset that will be very useful to understand the different dyamics of the sea ice in the Arctic and Antarctic.