Circumpolar wind

During the winter season in the South Pole, a strong circumpolar wind develops in the middle to lower stratosphere. Such strong winds, known as the polar vortex, isolate the air over the polar region. In the winter there is no sunlight and the air contained in the vortex becomes very cold (i.e., temperatures below — 80°C) leading to the formation of the polar stratospheric clouds (PSC). These PSC are composed not only of water but also of nitric acid trihydrate. 

Fig. 3.6 Mean October levels of total ozone above Halley Bay (76°S), Antarctica, since 1957. The 1986 value is anomalous due to deformation of the ozone hole, which left Halley Bay temporarily outside the circumpolar vortex (a tight, self-contained wind system). Dobson units represent the thickness of the ozone layer at sealevel temperature and pressure (where 1 Dobson unit is equivalent to 0.01 mm). Data courtesy of the British Antarctic Survey. Inset shows seasonally averaged (Sep.-Nov.) ozone partial pressure at about 17 km at 70°S. Data courtesy of G. Konig-Langlo.

Once in the ocean, the tides and currents driven by wind control the circulation of shallow water. Seven major currents, shown in Figure 2.1 [27], move water around the globe the West Wind Drift (or the Antarctic Circumpolar Current), East Wind Drift, the North and South Equatorial currents, the Peru Current, the Kuroshio Current, and the Gulf Stream. These currents can move quickly. The Gulf Stream, for example, usually travels at a speed of 3 or 4 knots, which is equivalent to 5.6 to 7.4 kilometers per hour [27]. As these currents spiral through the ocean they form five major gyres the North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian Ocean gyres. 

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