IMOS - ABOS Deepwater Arrays (DA) Sub-facility, Polynya array, Polynya3 Mooring Platform

The Polynya3 (Mertz region) deepwater mooring was deployed on 2011-01-23 at (-66.15 S, 143.01 E) off the Adelie Land Coast in Antarctica, and currently remains in place, inaccessible due to pack ice. In February 2014 a second array was deployed in a new location near the Totten Glacier.

Instrumentation includes 75kHz Acoustic Doppler Current Profilers (RDI longranger ADCPs), and Seabird SBE37s (SM, SMP and SMP-ODO).

The mooring will collect a time series of full-depth profiles of water velocity and discrete temperature and salinity measurement at four depth on each mooring, between the seafloor and 300m depth (the mooring are limited to this depth to avoid contact with icebergs).

This Polynya mooring array will re-continue the time series of bottom water export begun in 2008, using observation strategy, modified as required following recovery of the array in 2009.

The aim of the IMOS Polynya mooring array is to measure the export of dense Antarctic Bottom Water from the Adélie Land coast. Sinking of dense water near Antarctica supplies the deep branch of the global overturning circulation, a pattern of ocean currents that strongly influences climate. Several studies have recently shown that the properties of the bottom water in the Australian Antarctic Basin are changing. Monitoring the temperature, salinity and oxygen of bottom water will provide observations to detect how the Southern Ocean limb of the overturning circulation is responding to changes in high latitude climate forcing. The goal of the new Totten region location is to obtain measurements of "warm" inflow to, and (if possible) outflow from the Totten Glacier system. As it happened, access right to the Totten was not possible, and moorings were sited closer to the Dalton Iceberg Tongue and Moscow University Ice Shelf, possibly part of the Totten inflow story.