WEDNESDAY 29 February 2012
3pm in the Charnock Lecture Theatre
Miguel Angel Morales Maqueda
National Oceanogrphy Centre, Liverpool
ABSTRACT
Geothermal heating of abyssal waters is rarely regarded as a significant driver of the large-scale oceanic circulation. Indeed the heat released through the Earth's crust into the ocean is, on average, on the order of only 0.1 W m-2, peaking at about 0.5 W m-2 at the fast spreading East Pacific Rise. These figures are puny compared to average and extreme heat fluxes at the ocean surface. However, geothermal fluxes are unidirectional, always increasing the buoyancy of the abyssal ocean, and occur at the base of the water column, where their destabilizing effect is maximised. Heat fluxes associated with geothermal sources are in fact comparable in magnitude to fluxes caused by turbulent mixing in the deep ocean, which means that geothermal heating must be an important control of the abyssal circulation. However, several modelling works published in the early 2000s and investigating the impact of geothermal fluxes on abyssal currents and overturning circulations showed the geothermal contribution to be modest.The community is now taking a second look with more sophisticated models. Modellers from France, Germany, Japan, the United States and the UK have revisited the problem in the last few years and demonstrated that geothermal effects are far from negligible. On the observational side, a NERC funded project aiming at measuring the impact of geothermal heating on the stratification and circulation at the scale of an entire ocean basin will commence in a few months. All these new strands of research will be reviewed in this presentation.