Late winter oceanography off the Sabrina and BANZARE coast (117-128°E), East Antarctica

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Williams, GD, Meijers, AJS, Poole, A, Mathiot, P, Tamura, T, Klocker, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd 2011
• Subjects: Earth Sciences; Oceanography; Oceanography not elsewhere classified; Antarctic; Banzare Coast; Dalton Iceberg Tongue; East Antarctica; Moscow University Ice Shelf; The Antarctic; Antarc*; Antarctica; Ice Shelf; Iceberg*; Sea ice
• Online Access: https://doi.org/10.1016/j.dsr2.2010.10.035; http://ecite.utas.edu.au/76801

We report on the late winter oceanography observed beneath the Antarctic sea ice offshore from the SabrinaandBANZAREcoast ofWilkes Land, East Antarctica (1171281E) in SeptemberOctober 2007 during the Sea IcePhysics and Ecosystem eXperiment (SIPEX). A pilot program using specifically designed through-iceconductivity-temperature-depth (CTD) and acoustic Doppler current profiling (ADCP) systems was conductedto opportunisticallymeasure watermass properties and ocean currents atmajor ice stations. Additional watermass properties across the survey regionwere collected from Ice-Argo floats deployed during the voyage northof the 3000 m isobath. The mean drift of the floats was along the slope to the west with the Antarctic SlopeCurrent. Vertical profiles of the potential temperature reveal the deepest " 3502400 m winter mixed layer(WML) in the western sector of the survey northwest of the Dalton Iceberg Tongue polynya. The meridionalstructure of the Antarctic Slope Front, i.e. the monotonic shoaling of the WML across the upper continentalslope, is found to be similar to the previous observations in summer.A strong bottom-intensified intrusion ofmodified Circumpolar Deep Water (mCDW) as warm as 0 1C was detected beneath the fast ice south of thecontinental shelf break at 1181E. An mCDWintrusion of similar strengthwas detected near this location in theaustral summer of 1996.We hypothesise that there is a persistent supply ofmCDWand associated ocean heatflux to this region of the continental shelf that is capable of migrating to the grounding lines of the nearbyTotten Glacier and Moscow University Ice Shelf. There was no detection of locally formed dense shelf watercapable of forming Antarctic BottomWater at the shelf break locations sampled despite the number ofminorpolynyas across this region.Ocean currentmeasurements, limited to amaximumperiod of 24 h and 50100 mdepth by the relative scarcity of backscatter, found increased mean vertical speeds at the offshore stations(617 cm s$1) relative to the shelf break (2.36.4 cms$1). The diurnal variation in the ADCP range reflectedthe dielmigration of zooplankton occurring beneath the sea ice in late winter, with greater range/abundanceoffshore. Concurrent time series of wind, ocean current and their influence on sea ice drift from globalpositioning system (GPS) compass measurements were examined but the length of data acquisitions limitedthe applicability of this analysis.