The Development and possible recovery of the Antarctic Ozone Hole.
Degree GrantorUniversity of Canterbury
Degree LevelPostgraduate Certificate
Degree NamePostgraduate Certificate in Antarctic Studies
Since its prediction and discovery, ozone depletion in the stratosphere over Polar Regions has been a topic of widespread interest and debate. Starting in the late 1970s, when the Antarctic ozone observations began, there has been a dramatic decrease in ozone during the polar spring each year (WMO, 2003). The total amount of column ozone regularly goes below 220 DU1 in the atmosphere above Antarctica, at which point it is defined as an ozone hole (Newman et al., 2004). Whilst the influences on the mechanisms that cause this dramatic ozone loss each year are many, the essential prerequisites for ozone destruction are stratospheric chlorine and bromine (WMO, 2003). In the few years after 1979, the depletion of ozone rapidly increased from year to year due to the increased emission of chlorofluorocarbons (CFCs) through anthropogenic industrial activities. The tropospherestratosphere2 exchange at low latitudes allows compounds such as CFCs to enter the stratosphere. Once there, these compounds are transported to the poles via Brewer-Dobson3 circulation (Reid, 2000). Here they have very long lifetimes and they can continuously destroy ozone for several decades. This one part of the reason, why the effective ban on the emission of CFCs agreed to in “The Montreal Protocol on Substances that Deplete the Ozone Layer” in 1989 (Solomon, 1999) has not yet resulted in a significant reduction of the size of the Antarctic ozone hole. Furthermore, the actual extent of ozone destruction is also influenced by other factors such as the polar vortex, polar stratospheric clouds, temperature, water vapour, aerosols and planetary wave activity, which are highly interdependent. How they contribute to severe ozone depletion over Antarctica and why the recovery of stratospheric ozone is believed to be in progress, although still undetected, will be discussed in this paper.
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