ELEPHANT SEALS AS POLAR OCEAN OBSERVERS New evidence for the dense shelf water source of Cape Darnley Bottom Water and more. Guy Williams - AUV/Sea

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1 ELEPHANT SEALS AS POLAR OCEAN OBSERVERS New evidence for the dense shelf water source of Cape Darnley Bottom Water and more. Guy Williams - AUV/Sea Ice Specialist

2 UNDER-ICE WITH AN IMOS AUV (BUT NOT THE IMOS AUV) Williams et al., 2012 (under review EOS)

3 TODAY EXQUISITE DATA FROM IMOS SEALS Courtesy M. Hindell

4 WHY ANTARCTIC BOTTOM WATER? IPCC M. England OCCUPIES THE ABYSSAL OCEAN SURFACE->ABYSS DRIVES MOC ITS CHANGING Purkey and Johnson, 2010

5 AABW PRODUCTION WHAT WE RE MISSING Very challenging in winter CDW Williams et al., 2010 (JGR) The Missing Link between HSSW and AABW

6 30-YR OLD PUZZLE OF AABW IN WEDDELL-ENDERBY Meijers et al., 2011 (DSR) Locally formed AABW near 70º E from Oxygen - Jacobs and Georgi (1977) Further evidence offshore from tracer studies - Mantisi et al., 1991, Meredith et al., 2000, Meijers et al.,2010 Prydz Bay the initial focus Inconclusive Satellite data shifts focus to Cape Darnley Courtesy Tamura

7 JAPANESE IPY-MOORING PROJECT >300m thick layer of new cold, dense AABW at 2600m from end of May Bottom-intensified, currents > 0.5 ms -1, ~4-5 period. Linked to Cape Darnley, but not observed due to logistic constraints Courtesy Ohshima and Fukamachi

8 IMOS SEALS DAVIS DEPLOYMENT MARCH->JUNE

9 And then seal# 7202 had a change of heart Cape Darnley polynya

10 heading back to Cape Darnley in winter

11 Buried in the archives: French seal visited in Jan 2007

12 2011 Kerguelen seals arrive Sep-Oct on upper slope

13 Intense sampling of Shelf and Shelf Break

14 Very Dense Shelf Water on Cape Darnley Shelf Salinity > 34.8, a maximum of ~35! Summer Fall Mertz Cape Darnley Winter

15 MODIFIED SHELF WATER OVERFLOWS IN WINTER A shift to more saline bottom values in overflows from Cape Darnley (~34.65) and Prydz Bay (~34.6) Summertime obs. from BROKE West The Missing Link between HSSW and AABW

16 Cape Darnley Bottom Water now on the map Seasonal observations of VERY dense shelf water west of Cape Darnley Winter and remnant Summer values exceed 34.8 Dense Shelf water from Prydz Bay Weaker than Cape Darnley (~34.6) Likely to contribute to AABW from this region, in particular in strong years. Need to quantify Prydz Bay outflow in Winter VERY rare observations of dense shelf water overflow in winter Shift at ~69ºE to more saline modified shelf water, indicative of dual Cape Darnley Southward presence of mcdw NEW PARADIGM POLYNYAS ON NARROW/SHALLOW CONT. SHELVES CAN PRODUCE AABW IMOS seal data critical to the conditional acceptance of a revised manuscript under review with Nature Geoscience introducing Cape Darnley Bottom Water to the world

17 OTHER EXCITING RESULTS AROUND PRYDZ BAY Validation for Satellite estimates of sea ice production Circulation and warm mcdw intrusions Ocean/Ice Shelf Exchange

18 and across the south ACC to Kerguelen/Heard Is. Monthly snapshots of Winter Mixed Layer development across SIZ/SACCZ Jan/Fe b Mar/Apr Apr/May May June July

19 EVIDENCE OF AABW FROM VINCENNES BAY AT 110ºE Courtesy Kitade

20 IMOS Elephant Seals as Polar Oceanographers A truly awesome dataset Over 30,000 CTD profiles so far from Davis and Casey New aspects of spatial and temporal variability that challenge existing orthodoxy, sig. impact. Opportunity for SOOS/SENTINEL More tags to be deployed in 2013 Repeat coverage in Prydz Bay and across the Southern Ocean to Kerguelen and Heard Is. Very cost effective Needs a very high priority for ongoing logistic support to maintain this program AAD support for 2013 withdrawn AAD concern over use of physical oceanographic data vs ethics approval for biology Data not accessed through IMOS, but SMRU Courtesy D. Kamien

21 Courtesy M-A. Lea with Mark Hindell, Iain Field and Fabien Roquet (seals), Takeshi Tamura (sea ice) and Laura H-B (Prydz Bay), K. Ohshima and Y. Fukamachi (Cape Darnley) and Y. Kitade (Vincennes Bay) Extended IMOS data to form the basis of a PhD project to be advertised through CSIRO UTAS QMS