The Spirit of Mawson - Australasian Antarctic Expedition 2013 - 2014

Australasian Antarctic Expedition

Oceanography

The Southern Ocean plays a key role in global climate. Connecting all other oceans, it is critical for the transport of heat, salt and nutrients and long-term storage of carbon. Yet, because of its remoteness and relatively hostile environment, the Southern Ocean is also the least visited of the global oceans. All new observational data are therefore extremely valuable, especially at this time of rapid climate change. Crucially, Commonwealth Bay is a a major source of the coldest, densest water formed anywhere in the world’s ocean: Antarctic Bottom Water (sometimes shortened to AABW). But with the arrival of giant iceberg B09B some researchers have suggested the amount of AABW formation has dramatically reduced with unknown consequences for the global ocean circulation system.

The research program

1. On the AAE 2013-2014 we set out to discover how the Southern Ocean regulates our climate and plays a pivotal role in the global ocean circulation.

2. On the AAE 2013-2014 we undertake unique measurements of the mixing on the surface of the Southern Ocean, and how this impacts the connectivity between Antarctica and the rest of the world.

3. On the AAE 2013-2014 we wanted to document the rapid changes in ocean temperature and salinity around Commonwealth Bay.

Research Papers

Pairwise surface drifter dispersion in the western Pacific Sector of the Southern Ocean

van Sebille, E., Waterman, S., Barthel, A., Lumpkin, R., Keating, S.R., Fogwill, C. and Turney, C.

The Southern Ocean plays a critical role in global climate, yet the mixing properties of the circulation of the ocean remain poorly understood. Deploying drifters across the Southern Antarctic Circumpolar Current Front we report the first direct measurements of mixing in the region and demonstrate the importance of small-scale eddies for the transport of heat and nutrients across this important oceanographic boundary.

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Impacts of a developing polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg B09B

Fogwill, C.J., van Sebille, E., Cougnon, E.A., Turney, C.S.M., Rintoul, S.R., Clark, G.F., Marzinelli, E.M., Rainsley, E.B. and Carter, L.

Here we report new data from in-situ oceanographic surveys and high-resolution ocean modelling experiments in the Commonwealth Bay region of East Antarctica, where in 2010 there was a major reconfiguration of the regional icescape due to the collision of the 97 km long iceberg B09B with the Mertz Glacier tongue. We compare post-calving observations with high-resolution ocean modelling which suggest that this reconfiguration has led to the development of a new polynya off Commonwealth Bay.

Read the summary News and Views on our work in Nature Geoscience at http://www.nature.com/ngeo/journal/v9/n12/full/ngeo2853.html

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