The international team measured mixing in the Southern Ocean by releasing tiny quantities of an inert chemical tracer into the Southeast Pacific and then tracking it for several years as it went through Drake Passage – the channel between the southern tip of South America and the Antarctic continent. As the tracer moved across the Pacific, it showed almost no vertical mixing of water, but as the water rushed over undersea mountains in the relatively narrow continental gap that forms Drake Passage, it began to mix dramatically.
Ocean mixing transfers atmospheric carbon dioxide to the deep sea, while also affecting the transport of heat around the oceans, so it plays a crucial role in global climate. ‘A thorough understanding of the process of ocean mixing is crucial to our understanding of the overall climate system,’ said Andrew Watson of the University of Exeter, the study’s lead author. ‘Our study indicates that virtually all the mixing in the Southern Ocean occurs in Drake Passage and at a few other undersea mountain locations. Our study will provide climate scientists with the detailed information about the oceans that they currently lack.’
This story was published in the November 2013 edition of Geographical Magazine