Antarctic team measures currents under 275 m of ice with Aquadopp

The Woods Hole Oceanographic Institution (WHOI) research program, located at the Coulman High region of the Ross Ice Shelf in Antarctica, is primarily intended to support the operational needs of the National Science Foundation sponsored Antarctic geological drilling (ANDRILL) program by measuring currents under the Ross Ice Shelf. The Ross Ice Shelf field program presents a valuable opportunity to investigate processes under the ice shelf. WHOI worked with the New Zealand based National Institute of Water and Atmospheric Research (NIWA) and Victoria University of Wellington on this project.

In particular, the researchers focused on the following objectives:

• Assessing the tidal, seasonal and interannual variability of the water column structure and transport across the ice front, including influences on and response to ice shelf basal melt, sea ice formation and variability of the Ross Sea Polynya.
• Characterizing the under-ice-shelf boundary layer, the heat transport across this layer and scales of vertical mixing throughout the water column.

Two current meter moorings were deployed on November 24 and December 1, 2010 through the Ross Ice Shelf by Richard Limeburner and Will Ostrom (WHOI), Craig Stewart (NIWA) and Sanne Maas (Victoria University of Wellington, NZ). The WHOI mooring was located at the Coulman High site at 77° 26.211' S, 171° 32.391' E, approximately 70 nautical miles east-north-east of McMurdo Station, Antarctica. The mooring sites are normally covered with 300 m of ice.

Nortek Aquadopp and Sea-Bird MicroCAT inductive modem water flow instruments were placed at five levels below the ice shelf and a surface inductive modem logger and Iridium satellite communication package were installed on the ice surface of the WHOI mooring.

Real-time current velocity data from the water below the 275 m Ross Ice Shelf are available from the ANDRILL project. The data are available via Nortek Aquadopp Current Meters with integrated inductive modems.

Engineers from Woods Hole Group Inc developed and tested the surface inductive modem package with data logger, Iridium communications package and self-contained internal heater to keep the system functional in temperatures expected to drop below -40 °C.

Full details are available on the WHOI website.

Characterizing the under-ice-shelf boundary layer, the heat transport across this layer and scales of vertical mixing throughout the water column.

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