The strong and highly variable push of ocean waves on Southern Ocean sea ice
Abstract
Southern ocean sea ice plays a key role in regulating the uptake of carbon and heat by the global ocean. After a phase of expansion, the decline in sea ice since 2016 has taken experts by surprise, highlighting our poor understanding of ice dynamics. Ocean waves are known to play an important role in ice break-up and formation, contributing to the differences between Arctic and Antarctic sea ice. Yet, very little wave data was available so far. In this study we provide a new and extensive dataset on wave heights in sea ice, and its decay, using satellite radar data. It possible to wave spectra in sea ice from the satellite imagery because the presence of sea ice generally removes the blurring effects of short wave components. Most wave spectra have a narrow directional distribution. The observations support the idea that the attenuation of waves with periods longer than 10 s is dominated by dissipation processes with a limited effect of scattering. As waves decay they exert a force in their propagation direction that compacts the ice. We find that wave decays much stronger than previously reported meaning that the force on the ice can be very strong, and varies over two orders of magnitude. These results suggest that strong decays should be linked to ice rafting near the ice edge. Wave-ice interaction may thus have a profound impact on both extent and thickness of sea ice.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C21D1378S
- Keywords:
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- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSESDE: 3349 Polar meteorology;
- ATMOSPHERIC PROCESSESDE: 0750 Sea ice;
- CRYOSPHEREDE: 4540 Ice mechanics and air/sea/ice exchange processes;
- OCEANOGRAPHY: PHYSICAL