Antarctic Bottom Water from the Adelie and George V Land coast, East Antarctica (140-149 E)

• Published in: Journal of Geophysical Research
• Main Authors: Williams, GD, Aoki, S, Jacobs, SS, Rintoul, SR, Tamura, T, Bindoff, NL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2010
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Antarctic; East Antarctica; George V Land; Australian Antarctic Basin; Australian-Antarctic Basin; Buffon; Antarc*; Antarctica
• Online Access: http://www.agu.org/; https://doi.org/10.1029/2009JC005812; http://ecite.utas.edu.au/68308

We report on observations of dense shelf water overflows and Antarctic Bottom Water(AABW) formation along the continental margin of the Adlie and George V Land coastbetween 140E and 149E. Vertical sections and bottom layer water mass propertiessampled during two RVIB Nathaniel B Palmer hydrographic surveys (NBP0008,December 2000/January 2001 and NBP0408, October 2004) describe the spreading ofcold, dense shelf water on the continental slope and rise from two independent sourceregions. The primary source region is the Adlie Depression, exporting high‐salinity denseshelf water through the Adlie Sill at 143E. An additional eastern source region of lowersalinitydense shelf water from the Mertz Depression is identified for the first timefrom bottom layer properties northwest of the Mertz Sill and Mertz Bank (146E148E)that extend as far as the Buffon Channel (144.75E) in summer. Regional analysis ofsatellite‐derived ice production estimates over the entire region from 1992 to 2005suggests that up to 40% of the total ice production for the region occurs over the MertzDepression and therefore this area is likely to make a significant contribution to the totaldense shelf water export. Concurrent time series from bottom‐mounted Microcats andADCP instruments from the Mertz Polynya Experiment (April 1998 to May 1999) near theAdlie Sill and on the upper continental slope (1150 m) and lower continental rise (3250 m)to the north describe the seasonal variability in downslope events and their interactionwith the ambient water masses. The critical density for shelf water to produce AABWis examined and found to be 27.85 kg m−3 from the Adlie Depression and as low as27.80 kg m−3 from the Mertz Depression. This study suggests previous dense shelfwater export estimates based on the flow through the Adlie Sill alone are conservativeand that other regions around East Antarctica with similar ice production to the MertzDepression could be contributing to the total AABW in the Australian‐Antarctic Basin.