2013-2014 Science Planning Summaries
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DIMES finestructure profiling floats: Analysis and enhancement of the EM-APEX array upstream and downstream of Drake Passage

Program Manager:
Dr. Peter Milne

Event Number: O-409-L

ASC POC/Implementer:
Addie Coyac

Dr. James Bannister Girton (Principal Investigator)
http://dimes.ucsd.eduExternal Non U.S. Government Site

University of Washington
Seattle, Washington

Supporting Stations:  ARSV Laurence M. Gould
Research Locations:  Drake Passage / Scotia Sea

Project Description:
Southern Ocean mixing has the potential to play an important role in the Meridional Overturning Circulation, but considerable uncertainty still exists as to the locations and processes responsible for the most mixing. The DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) tracer release, together with 10 EM-APEX profiling floats (an Argo float with Sanford-type electromagnetic velocity measurement) and ship microstructure surveys, has quantified the mixing in the southeast Pacific Ocean west of the Drake Passage, revealing modestly elevated mixing due to wind-generated near-inertial waves, but has yet to extend fully into the high-energy environments of Drake Passage and the Scotia Sea. The shear measurements of the EM-APEX have proven a valuable tool for the characterization of the Southern Ocean's internal wave field (the "finestructure" seen in velocity and density profiles with wavelengths between 10 and 1000 meters). This inclusion of shear is particularly necessary given the predominance of near-inertial waves with relatively weak signature in density, i.e., high shear-strain ratios. The combination of high-quality shear and density profiles over the upper 2000 meters and sustained duration makes the EM-APEX an economical choice for extending these types of measurements into the less well-sampled regions and times of the year.

Field Season Overview:
This project will deploy 5 EM-APEX profiling floats to extend the coverage of the current observational array within Drake Passage and the Scotia Sea and fill gaps in the seasonal cycle.

Deploying Team Members:

  • James Girton (PI)

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