The global meridional overturning circulation of the oceans (a major component of the thermohaline circulation) is forced by density differences owing to heat and water fluxes at the sea surface. Wind stress on the surface and injections of energy into turbulent mixing from the winds and tides modify this circulation. In our approach we examine the extent to which the density differences and interior turbulent mixing together, but in the absence of large-scale wind stresses, could force the overturning. The fundamental dynamics of convective overturning is being examined using experiments in the Geophysical Fluid Dynamics laboratory. The ultimate goal is to determine the role of such convection in the global circulation.

Relevant Papers:

• Hughes, G.O. and Griffiths, R.W. (2005) A simple convective model of the global overturning circulation, including effects of entrainment into sinking regions. Ocean Modelling 12 , 46-79 (doi:10.1016/j.ocemod.2005.04.001).
• Hughes, G.O. Griffiths, R.W., Mullarney, J.C. and Peterson, W.H. (2006) A theoretical model for horizontal convection at large Rayleigh number. J. Fluid Mech ., in press, to appear June 2007.
• Mullarney, J.C., Griffiths, R.W., and Hughes, G.O. (2007) The role of freshwater fluxes in the thermohaline circulation: insights from a laboratory analog. Deep-Sea Res. I , doi:10.1016/j.dsr.2006.10.001.