Observation of Sea-ice Effects on Deep Internal Waves in the Southern Drake Passage

초록

The recent sea-ice melting accelerated in the Arctic has been suggested to enhance the internal wave energy at the shelf and deep ocean, although supportive evidence is rare partly due to the difficulty of long-term measurements under the sea ice. This study presents inter-annual variations of high-frequency internal wave energy affected by the sea ice using near-bottom current measurements from an array which was continuously deployed in the southern Drake Passage during 2007-2011. Integrated horizontal kinetic energy at periods shorter than 10.5 days during summers reveals no significant year-to-year differences, while that during winters shows a reduction by a factor of two and a half at the most southern site in 2011 when it was occupied by highly-concentrated sea ice. Our results support that the sea-ice extension changes related with climate changes can modulate the high-frequency internal wave energy in the deep ocean, which has a potential to affect ocean dynamics and ecosystems significantly in polar oceans.