C21A-0694
Access of warm Southern Ocean water along the East Antarctic Margin - first results from the NBP1503 cruise
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Frank Oliver Nitsche1, Raul Guerrero2, Guy Darvall Williams3, David Felton Porter4, Eva Cougnon3, Alexander Fraser3,5, Ricardo Correia6 and Dominique Richardson7, (1)Lamont -Doherty Earth Observatory, Palisades, NY, United States, (2)Instituto Nacional de Investigacion y Desarollo Pesquero, Mar de Plata, Argentina, (3)University of Tasmania, Institute of Marine and Antarctic Studies, Hobart, Australia, (4)Columbia University of New York, Palisades, NY, United States, (5)Hokkaido University, Institute of Low Temperature Science, Hokkaido, Japan, (6)University of Aveiro, Aveiro, Portugal, (7)Cabrillo Marine Aquarium, Long Beach, CA, United States
Abstract:
The future of the Antarctic Ice Sheet is one of the critical questions in assessing the effects of climate change. The East Antarctic Ice Sheet (EAIS) was regarded as relatively stable, and only recently has become the subject of a series of studies to determine if parts of the EAIS might be susceptible to melting if warm ocean masses reach the ice sheet. We are presenting new oceanographic and bathymetry observations from the East Antarctic continental margin between 115° E and 135° E that have been collected as part of the scientific cruise NBP1503 onboard the NB Palmer in early 2015. The goal of the scientific cruise was to determine to what extent warmer ocean water could reach (or is reaching) the inner shelf. Sea ice conditions prevented access to most inner continental shelf areas. Instead, we collected detailed multibeam bathymetry and Conductivity-Temperature-Depth (CTD) data from the continental slope, rise and the outer shelf north of the Dibble Glacier, Frost Glacier, Dalton Iceberg Tongue and Totten Glacier. An oceanographic section of 19 CTD stations on the continental slope parallel to the margin shows that modified Circumpolar Deep Water (mCDW) with higher salinity and temperatures is present near the shelf break over large sections of the investigated margin, but is absent in other sections. The shelf break depth varies significantly along the margin between ~300 and ~500 m. The shallower depths are potentially an obstacle for access of mCDW to the shelf. As a result, a ~100 m thick layer of mCDW resides on the ~500 m deep outer shelf north of the Totten Glacier, but there is no indication of mCDW in the Dibble Polynya because the shelf break is shallower. The access and presence of warmer mCDW water, especially north of Totten Glacier and the Moscow University Ice Shelf, has important implications in understanding the observed thinning of this ice stream.
