Lead Chief Investigator

Ross W Griffiths Earth Physics, Research School of Earth Sciences, Australian National University

Project Title

Modelling the ocean overturning circulation - identifying the fundamental processes

Brief Description for General Publications

The project investigates the processes that drive or govern the global overturning circulation of the oceans. It will thereby contribute to the understanding of the dynamics of climate and climate change. We specifically focus on the independent and combined roles of surface buoyancy fluxes, surface wind stress and interior turbulent mixing. We use ocean General Circulation Models (currently MITgcm), generally with extremely high spatial resolution and non-hydrostatic mode, as necessary to properly resolve and model the regions of vertical convection. The computing demand is then off-set by defining idealised forcing and ocean geometries, so as to focus on the fundamental dynamics rather than simulation of the oceans. The numerical solutions are sometimes closely related to flows in our laboratory experiments, providing dynamical comparisons and extrapolations to wider parameter ranges. The project is leading to new understanding of the roles of buoyancy and turbulent mixing in the forcing and the energy budget of global circulation. In particular, we aim to further test our recent results that show surface buoyancy fluxes, which had previously been dismissed as unimportant for the oceans, are as important as wind stress for the mechanical energy budget of the oceans. The present aim is to test our theoretical prediction that the globally integrated rate of mixing is equal to the available potential energy generated by the surface buoyancy forcing.