Shackleton Centenary Expedition

Sponsored by Matrix & Timberland


Blue Ice Research

http://www.shackletoncentenary.org/about/blue-ice-research-1.php

We will carry out a Polar climate research project en route to the Pole.

The Beardmore Glacier is a major outlet glacier of the East Antarctic Ice Sheet. Its flow and dynamics reflect the integrated effect of accumulation of snow in its drainage basin (there may be a limited amount of ablation mainly by blowing snow). Most of the ice is discharged into the Ross Ice Shelf. There is however some loss by evaporation/sublimation and blowing snow on the Beardmore itself due to the strong katabatic winds. Some of this is revealed by areas of blue ice.

blue_ice_crevasse.jpg

Antarctic blue ice crevasse, McMurdo Sound

By examining the blue ice zones it is likely to be possible to determine something of the ice dynamics.


These are areas, if they have been maintained for a sufficient period because of ice loss at the surface, where the flowlines from the interior are angled upwards and intersect the surface.


The further away (inland) the origin the more vigorous and long-lived will have been the ablation or ice loss at the surface of the glacier. This is valuable information in evaluating the overall behaviour of the outlet and assists in understanding better its response to possible climate changes.


To test the idea of the origin of the ice in the outlet we will need to take a number of relatively small samples of uncontaminated ice from the blue ice zones (about 20ml).


To undertake this, we will need to extract ice chips from about 20-30cm below the ice surface (using a clean ice axe). The samples must be kept frozen, or melted only once as refreezing will reset the isotopes.


The samples will be returned to the UK where the melt water can be used to determine the isotopic composition by a specialised laboratory. The two key isotopes are 18O and Deuterium. The lower the isotopic signature the colder the snow when it was precipitated to form the ice and hence higher (ie. colder) in the drainage basin.


Such a study will be contingent on travelling across some blue ice areas on the Beardmore - but it is some of the best terrain for travel (ie. few or visible crevasses).


Some ideas gained early on from aerial photos and satellite images and discussions with people like Charles Swithinbank, will enable us to identify these zones for travel and sampling. We hope to gain some samples of snow from areas on the Ross Ice Shelf and on the route to the Pole from the Beardmore (say every 100km) in order to evaluate the spatial variation and add to our existing understanding of the regional isotopic signatures.


This study requires limited equipment and not too many samples and of low weight and bulk which can be easily airlifted back. The location and importantly the height of the samples can be determined by GPS.

Posted by SCE on September 19, 2006 4:20 PM