The Antarctic Ozone Hole

Source: NOAA TOVS satellite

Antarctic Ozone Levels in Fall 2003 The ozone hole is represented by the purple, red, burgundy, and gray areas that appeared over Antarctica in the fall of 2003. The ozone hole is defined as the area having less than 220 Dobson units (DU) of ozone in the overhead column (i.e., between the ground and space).

The ozone hole is a well-defined, large-scale destruction of the ozone layer over Antarctica that occurs each Antarctic spring. The word "hole" is a misnomer; the hole is really a significant thinning, or reduction in ozone concentrations, which results in the destruction of up to 70% of the ozone normally found over Antarctica.

The science of the ozone hole is quite complex, but our understanding of the many factors that combine to create it has improved greatly since the first investigations in the 1980s. Unlike global ozone depletion, the ozone hole occurs only over Antarctica. Using several instruments on satellites, planes, and balloons, scientists have produced detailed graphs of the size of the ozone hole.

Two international organizations issue regular bulletins about the ozone hole as it develops each year: the British Antarctic Survey and the World Meteorological Organization. The BAS site also explains why the ozone hole didn't occur in 1956, despite a widespread myth that it did. The University of Cambridge's Ozone Hole Tour provides detailed explanations, with graphics, of the ozone hole and its history.

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Daily and archived ozone hole graphics are available online from the National Oceanic and Atmospheric Administration (NOAA ).