MOCHA is a collaborative project, partnered with the UK RAPID Program, to measure the meridional overturning circulation (MOC) and ocean heat transport in the North Atlantic Ocean. These transports are primarily associated with the Thermohaline Circulation. Simply put, warm waters move poleward at the surface of the ocean, where they cool and sink, to return equatorward in the deep ocean.
An outstanding problem in the oceanic sciences is the rate of heat and freshwater transport from the equator to the poles, for it is this transport which powers the Earth's weather and climage system.