Expressions of Intent for IPY 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean: Mixing in the Antarctic Circumpolar Current  (DIMES)

Outline
The underlying motivation of DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) is to understand the meridional overturning circulation of the global ocean. This circulation is an important part of the ocean/atmosphere system that transports heat from the equator to the poles. It will play the dominant role on time scales of centuries in the uptake by the ocean of excess CO2 generated by the burning of fossil fuels and by net global deforestation. Thus, it will govern, on the same time scales, the response of the earth’s climate to this excess CO2 and to other perturbations to the radiation balance at the earth’s surface.The goals of DIMES are to measure the diapycnal diffusivity and mesoscale isopycnal diffusivity at several levels and in several environments in the ACC. The project will focus on the southeast Pacific, the Drake Passage and Scotia Sea, and the southwest Atlantic. Diapycnal diffusivity will be estimated from fine structure and microstructure measurements covering the whole water column, all across these regions, with special attention on features likely to generate strong mixing. Isopycnal diffusivity will be estimated from the trajectories of isopycnal floats released at two depths in the ACC. The diapycnal diffusivity of a passive tracer will be measured with a tracer release experiment on an isopycnal surface near 1500 meters depth, and the tracer patch will also give an independent estimate of mesoscale isopycnal diffusivity.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
DIMES seeks to develop a better understanding of physical processes that control the transport of heat and other climate signals in the region around Antarctica. Results from DIMES will inform our understanding of polar-global linkages and of the current state of the polar environment.

What international collaboration is involved in this project?
DIMES will involve research groups from the United States and the United Kingdom. The US group will submit a proposal in February 2005 to carryout tracer, float, and high-resolution profiler measurements. UK investigators will submit a proposal in June 2005, which will include participation in the tracer release experiment, as well as microstructure and fine structure measurements that would complement those of the U.S. HRP group. They may also propose sampling of the terrigenic Helium-3 plume in the Atlantic sector. The experiment will use both U.S. and U.K. ships. Contacts will be made with oceanographers in Chile and in Argentina for their cooperation and possible collaboration in the survey cruises.

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
The project will focus on the southeast Pacific, the Drake Passage and Scotia Sea, and the southwest Atlantic.

Approximate timeframe(s) for proposed field activities:
Arctic: n/a
Antarctic: 07-08            

Significant facilities will be required for this project:
Ship resources will be shared between the US and UK.

Will the project leave a legacy of infrastructure?
No

How is it envisaged that the required logistic support will be secured?
Own national polar operator
Another national polar operator
National agency

Has the project been "endorsed" at a national or international level?
Y? Endorsement from the US CLIVAR Steering Group as a CLIVAR process study.

PROJECT MANAGEMENT AND STRUCTURE

Is the project a short-term expansion (over the IPY 2007-2008 timeframe) of an existing plan, programme or initiative or is it a new autonomous proposal?
Yes

How will the project be organised and managed?
Proposals for the three major field components of DIMES are being submitted separately. The three components are synergistic, not only logistically, but scientifically as well. Microstructure and fine structure measurements are proposed by Toole and Schmitt of WHOI. The float measurements are proposed by Gille (SIO), Speer (FSU), and Owens (WHOI). The tracer release experiment is proposed by Ledwell (WHOI). Modeling support will be provided by M. Maltrud at Los Alamos National Laboratory and J. McClean at the Naval Postgraduate School.The US CLIVAR SSG and International CLIVAR SO Panel provide program oversight.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?

What are the initial plans of the project to address data management issues (as outlined in the Framework document)?

How is it proposed to fund the project?
US and UK National funding

Is there additional information you wish to provide?
None

PROPOSER DETAILS

Dr. Jim Ledwell
Woods Hole Oceanographic Institution
Woods Hole, MA
02543
USA

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Other project members and their affiliation

Other Information