Dr Allison said that scientists have known for some time that open water and thin ice regions called 'polynyas' occur near the Antarctic coast in areas otherwise covered by pack ice but this will be the first time that a research program will be undertaken in such a difficult working environment. This voyage is an opportunity to investigate for the first time oceanic conditions in and around the Mertz Polynya, together with key sea-ice, meteorological and biological observations. Exchanges of energy, water and gases between the ocean and atmosphere around Antarctica help determine conditions around the rest of the world. The research group will target the 'Mertz Polynya' near the coast of Adelie Land, almost directly south of Tasmania, in one of the windiest places on Earth. In fact, the researchers believe that it is these strong and persistent katabatic winds blowing down the Mertz Glacier which maintain the relatively ice-free conditions in the region.
Salt is removed from the ice as it forms, increasing the density of the underlying water.
This cold, dense water is known as Antarctic Bottom Water and sinks deep into the ocean carrying with it oxygen and other gases. Antarctic Bottom Water spreads its way through the depths of the world's oceans and plays a major role in the global ocean circulation. Water formed in this way is estimated to occupy about one quarter of the volume of the oceans. During an earlier voyage on the Aurora Australis in April this year seven oceanographic moorings were successfully laid in both open water and mid-winter pack ice regions adjoining the Mertz Glacier. The moorings, in depths from 500 metres to 3,000 metres, contain 34 instruments which will measure water temperature from near the surface to the ocean floor, as well as record salinity, fluctuations in ocean current, sea-ice thickness and pressure.