The far-reaching significance of deep cold temperatures in the ocean was first realized by Count Rumford in 1797. Rumford, in analyzing ship-recorded temperatures obtained almost 50 years earlier, inferred a polar origin for the deep water masses and a corresponding meridional overturning circulation to carry deep cold waters equatorward and warm surface waters poleward.

We now know that this circulation is driven by heat and/or freshwater loss at the ocean surface in a few special regions near to the poles, and refer to it as the thermohaline circulation. This circulation transports a considerable amount of heat, and in so doing strongly moderates weather and climate. For this reason, in view of anthropogenically induced changes in atmospheric carbon dioxide and the resultant possibility of global warming, we need to understand how the oceans' role in storing and transporting heat will vary in response to climate change.

The wealth of recent data from programs such as the World Ocean Circulation Experiment (WOCE) indicates clearly that ocean models are currently lacking in their representation of deep water mass properties and circulation. A significant part of this is likely due to the poor representation of intense mixing and bottom boundary processes occurring at overflows, where many deep and intermediate water masses are sourced. This is therefore one of the most important problems to be addressed in current ocean models.