ABSTRACT

Antarctica, which is the area south of 60°S, is the most pristine and least populated continent on Earth. It is separated from the other continents by the Southern Ocean, which, at its narrowest between the Antarctic Peninsula and South America, is 1000 km wide (Hughes et al., 2006). When Antarctica broke away from South America ∼30 million years ago, the formation of the circumpolar Southern Ocean and atmospheric current initiated a cooling process that has resulted in the frozen continent found today. Permanent ice sheets cover 99.6% of the land surface and the remaining ice-free land is composed of rocky nunataks that rise through the surrounding ice sheet and coastal areas, including the expansive continental Dry Valley region. In general, as latitude increases, mean annual temperature and therefore liquid water availability decreases, ultraviolet (UV; 280-400 nm) radiation ux increases and seasonal variations in daylight duration become more pronounced. Stratospheric ozone depletion during the austral spring may also increase the levels of incident UV radiation, particularly at high latitudes.