2013-2014 Science Planning Summaries
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Studies of turbulence and mixing in the Antarctic Circumpolar Current, a continuation of DIMES

Program Manager:
Dr. Peter Milne

Event Number: O-124-N

ASC POC/Implementer:
Addie Coyac

Dr. James Robert Ledwell (Principal Investigator)
http://dimes.ucsd.edu/External Non U.S. Government Site

Woods Hole Oceanographic Institution
Dpt. of Applied Ocean Physics & Engineering
Woods Hole, Massachusetts

Supporting Stations:  RV/IB Nathaniel B. Palmer
Research Locations:  Drake Passage / Shackleton Fracture Zone

Project Description:
The objective of this project is to sample a tracer that was released in the Antarctic Circumpolar Current on a surface of constant neutral density near 58 degrees S Latitude, 106 degrees W Longitude in 2009. The tracer is making its way through the Drake Passage, into the Scotia Sea, and beyond into the Argentine Basin as it spreads horizontally and vertically. The ultimate objective of the tracer experiment is to measure this spreading. The depth of the tracer cloud varies from about 2,000 meters to the north of the Subantarctic Front to less than 300 meters along the Antarctic continental slope. The tracer is trifluoromethyl sulfur pentafluoride and is analyzed in seawater samples on board the RV/IB Nathaniel B. Palmer using a gas chromatograph with electron capture detector.

Field Season Overview:
Researchers will sail on the R/V Nathaniel B. Palmer on a 20-day expedition. We will occupy approximately 25-50 hydrographic sample stations along the Phoenix Ridge and Shackleton Fracture Zone. Their sample locations will be adapted to occur within the frontal zones of Drake Passage. They will conduct numerous conductivity-temperature-depth (CTD) casts at various stations and will employ an autonomous deep microstructure profiler (DMP). At each station, they will also use the NBP's multibeam system to examine the seafloor topography.

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