***UPCOMING SEMINAR***
Elephant Seals as Polar Ocean Explorers – Uncovering new sources of dense shelf water formation for Antarctic Bottom Water production and more
Speaker: Guy Williams (AUV / Sea Ice Specialist - ACE CRC, University of Tasmania)
Date: TUESDAY 7 August 2012, 11:00 AM
Venue: Theatrette, Australian Antarctic Division, 203 Channel Highway, KINGSTON, Tasmania
New oceanographic datasets from instrumented
marine mammals have been addressing critical spatial and temporal gaps
in our understanding of the polar oceans. This is particularly true
south of the Antarctic continental shelf break
in the coastal polynya regions that form dense shelf water for the
production of Antarctic Bottom Water (AABW). In 2011, IMOS instrumented
southern elephant seals (Mirounga leonina) from Davis Station and
Kerguelen Island foraged extensively over the Prydz
Bay/Cape Darnley region (65-80ºE) from February to October.
Historically this eastern sector of the Weddell-Enderby Basin was
identified from offshore bottom properties as having a local source of
AABW. The dense shelf water source was speculated to be Prydz
Bay, but never confirmed. Recent satellite analyses found that the
Cape Darnley polynya, directly west of Prydz Bay, had the 2nd highest
sea ice production around Antarctica. A subsequent Japanese IPY mooring
program in 2008 revealed the first direct observations
of new AABW production offshore from Cape Darnley, but could not sample
the shelf region due to logistic constraints. The elephant seals
deployed in 2011 have not only confirmed the presence of very High
Salinity Shelf water west of Cape Darnley (up to 34.9),
relative to dense shelf water from the Prydz Bay region, but have also
captured very rare wintertime observations of the modified shelf water
overflows to depths of ~1700m in wintertime. This talk will present
these results and showcase other unique insights
the IMOS seals are delivering on the East Antarctic margin of the
southern ocean.
