Figure 6.26 shows how the modified North Atlantic Deep Water/Antarctic Circumpolar Water/Circumpolar Deep Water flows up between Antarctic Intermediate Water and the very dense Antarctic Bottom Water, and rises towards the Antarctic Divergence (Section 5.5.2). Thus, warm water carried downwards in the subtropical gyres is transported polewards and then upwards until eventually it reaches the surface of the ocean around Antarctica, where a large amount of heat is given up to the atmosphere. Cooled water flowing northwards from the Antarctic Divergence will sink at convergences in the Antarctic Polar Frontal Zone in the form of Antarctic Intermediate Water, while that flowing polewards from the Antarctic Divergence may eventually be converted to Antarctic Bottom Water (Figure 6.26). The cycle of water mass formation is therefore an intrinsic part of the thermohaline circulation which, along with the surface current system, redistributes heat around the globe.
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