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Firsthand Learning of the Circulation and Stratification off Sabrina Coast, Antarctica
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Air-sea-ice interaction observed within the Sabrina Basin, East Antarctica are likely widespread along the Antarctica margins, therefore this study is relevant to explaining and predicting current mass loss trends in other Antarctic ice shelves and glaciers. Water mass structure, mixing history and flow patterns over the continental shelf off Sabrina Coast (115 °E - 122 °E) are described using the first observations made during the multi-disciplinary U.S. cruise of 2014 and the follow up Australian cruise of 2015 and based on dynamic topographies at selected levels, property distributions on specific isopycnals and levels. Two large cyclones are inferred over the shelf, an elongated one connecting slope waters to the eastern end of the escarpment, and a zonally-oriented cell connecting the westward boundary current along the northern escarpment to the interior of the Dalton Basin. Unlike the available Modified Circumpolar Deep Water near the shelf break, the lighter Thermocline Water is able to enter the shelf over the Dalton Basin sill (~450 m), progressively deepening within the bottom layer temperature maximum of an eastern boundary current found against the western flank of the Dalton Plateau (450 m – 550 m). Near the southern end of the Plateau its densest remnant branches westward and further sinks to depths greater than 550 m supplying the warmest bottom layer within the southern limb of the Dalton Basin cyclone. Relatively lighter Thermocline Water (γ^n = 27.90 kg m^3) lying at about 150 m near the shelf break extends to over the escarpment at 450 m, and supplies multiple trenches connected to Moscow University Ice Shelf with source water warmer than -1.7 °C at 560 m available for basal melt. Directly above this inflow, a prominent Meltwater-bearing outflow is observed at the Central Trench of this Ice Shelf over a 300-m thick layer with water colder than -1.8 °C and fresher than 34.22 (γ^n < 27.90 kg m^3), whose downstream influence throughout the Sabrina Basin cyclonic flow is evident by a thickened thermostad layer and much deeper interior thermocline than over the eastern shelf. Ventilation of the oceanic Thermocline Water takes place along a tight anticyclonic loop west of the Dalton Iceberg Tongue. Here, a relatively warm (θ > -1.83 °C) and saline (S > 34.30) southeastward inflow at 200 m (γ^n > 27.90 kg m3) impinges onto the northern Tongue, and emerges off its tip as a fresh (S < 34.22) and lighter (γ^n < 27.80 kg m^3) plume injected northwestward into the Antarctic Slope Current.
Zielinski, Natalie Jane (2016). Firsthand Learning of the Circulation and Stratification off Sabrina Coast, Antarctica. Master's thesis, Texas A & M University. Available electronically from