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Isotopic and chemical composition of Antarctic shelf ice: implications for global changes

More:  Institutes 
Reference no: A3/11/002
Period: September 1992 till September 1996
Status: Completed

Institutes (2)  Top 
  • Université Libre de Bruxelles; Faculté des Sciences; Département des Sciences de la Terre et de l'Environnement; Laboratoire de Glaciologie, more
  • Belgian Science Policy (BELSPO), more, sponsor

Abstract:
The purpose of this research is to analyze the chemical and isotopic properties of ice formed at the interface between a small Antarctic ice shelf and the ocean, in so far as these can contribute towards a better understanding of the role that climatic changes can play in the stability of this type of ice shelf. The latter is likely to react rapidly to climatic changes connected with human activities. In fact, its stability is closely dependent on changes in the temperature o f the oceanic waters with which it comes into contact.

The climatic changes forecast for the 21st century could lead to an increase of around 0.5°C in the average temperature o f these oceanic waters. The response of small Antarctic ice shelves to a climatic change and their influence on the world sea level depend on changes in their conditions at the margins. The thermodynamic processes occurring at their bases control the melting or accretion of sea ice there.

An analysis o f the chemical and isotopic composition o f the ice formed at the ice shelf/ocean interface is a way of gaining a better understanding o f the conditions prevailing there. In effect, the properties of sea ice reflect the properties o f the water which produced them and these in turn define the melting or freezing conditions.

OBJECTIVES

To determine the conditions prevailing at the ice shelf/ocean interface from a chemical and isotopic analysis of the sea ice formed at this interface, coupled with a crystallographic examination. Three types of situations will be examined in particular:

- Accretions of sea ice at the base of ice shelves, which rise to the surface following ablation. Such situations can be observed in the Victoria Land region, where the lower section of a number of small ice shelves is made up entirely of sea ice formed at their base following ablation linked with katabatic winds. Analyses of this ice will allow much more information to be obtained than that collected from affected ice during limited sampling.

- The basal ice created at the anchor line where the glacier gives way downstream to the floating ice shelf. Such ice can be seen at the surface in the Terra Nova Bay region.

- The sea ice produced in crevasses affecting the ice shelves, whose properties depend on the characteristics of the water under the ice shelves. The floating George VI ice shelf in Western Antarctica and the Nansen ice shelf in Victoria Land are favourable to this type of study.

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