DIMES

DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) is a US/UK field program aimed at measuring diapycnal and isopycnal mixing in the Southern Ocean.

The Meridional Overturning Circulation (MOC) of the ocean is a critical regulator of the Earth's climate processes. Climate models are highly sensitive to the representation of mixing processes in the southern limb of the MOC, within the Southern Ocean, although the lack of extensive in situ observations of Southern Ocean mixing processes has made evaluation of mixing somewhat difficult.

Theories and models of the Southern Ocean circulation have been built on the premise of adiabatic flow in the ocean interior, with diabatic processes confined to the upper-ocean mixed layer. Interior diapycnal mixing has often been assumed to be small, but a few recent studies have suggested that diapycnal mixing might be large in some locations, particularly over rough bathymetry. Depending on its extent, this interior diapycnal mixing could significantly affect the overall energetics and property balances for the Southern Ocean and in turn for the global ocean. The goals of DIMES are to obtain measurements that will help us quantify both along-isopycnal eddy-driven mixing and cross-isopycnal interior mixing.

Research Papers

Ledwell, J. R., L. C. St. Laurent, J. B. Girton, and J. M. Toole (2011), Diapycnal mixing in the Antarctic Circumpolar Current, J. Phys. Oceanogr., 41, 241-246, doi:http://dx.doi.org/10.1175/2010JPO4557.1.

St. Laurent, L., A. C. Naveira Garabato, J. R. Ledwell, A. M. Thurnherr, J. M. Toole, and A. J. Watson (2012), Turbulence and diapycnal mixing in Drake Passage, J. Phys. Oceanogr., 42, 2143–2152, doi:http://dx.doi.org/10.1175/JPO-D-12-027.1.

Sheen, K. L., J. A. Brearley, A. C. Naveira Garabato, D. A. Smeed, S. Waterman, J. R. Ledwell, M. P. Meredith, L. St. Laurent, A. M. Thurnherr, J. M. Toole, and A. J. Watson (2013), Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES), J. Geophys. Res. Oceans, 118, 2774–2792, doi:10.1002/jgrc.20217.

Watson, A. J., J. R. Ledwell, M.-J. Messias, N. Mackay, M. P. Meredith, B. Mills, and A. C. Naveira Garabato (2013), Rapid cross-density ocean mixing at mid depths in Drake Passage, Nature, 501(7467), 408–411, doi:10.1038/nature12432.