Towards a Global Representation of the Impact of Ocean Mixing Processes on Large Scale Circulation

Turbulent mixing in the ocean controls transport of heat, freshwater, dissolved gasses, and pollutants. Turbulent mixing is also of crucial importance for ocean biology, from determining the flow field for the smallest plankton to setting large-scale gradients of nutrient availability. Recent work suggests considerable spatial and temporal non-homogeneity in deep-ocean mixing; an improved understanding of the distribution of deep-ocean mixing intensity, and the physics that drives that distribution, is central to understanding the energetics of the ocean and reducing the uncertainties in global circulation and climate models. Observations of turbulent mixing in the ocean include direct measurements of velocity and temperature fluctuations at the small scales (mm to cm) of turbulent overturns, observations of net mixing by purposeful dye release, focused studies of the dynamical processes that lead to turbulence, and inferences of mixing from larger scale budgets. The physics of ocean mixing is also actively studied using a variety of numerical and theoretical approaches, as well as laboratory experiments. Finally, the consequences of mixing for larger scale climate models are addressed by turning dynamical insights of the previously mentioned work into practical parameterizations.

The purpose and scope of this GRC is to provide a forum for discussion of the rapidly evolving field of ocean mixing. Emphasis is threefold: observations of mixing in the world, new insights into dynamics that control mixing rates, and impacts of mixing on regional and global circulation and budgets. The latter two include development of parameterizations to turn dynamical insights into useful things to include in regional models and global numerical climate models.