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Victoria University Antarctic Research Expedition Science and Logistics Reports 2007-08: VUWAE 52

e. Results and discussions

e. Results and discussions

Ground Penetrating Radar (GPR)

Traverses totaling 150km at Skinner Saddle and 35km at Gawn Ice Piedmont have been surveyed with GPR. The measurements allowed us to identify an excellent drilling location at Skinner Saddle with smooth bedrock topography and a glacier thickness exceeding 600m at the proposed drilling location. Excellent isochrone reflections are visible throughout the profile to below 150m, which will also be used to investigate geographical and chronological accumulation changes. The region at Gawn Ice Piedmont is glaciologically more active (see Figure 9) and marginal weather conditions limited our ability to a more comprehensive survey, as achieved at Skinner Saddle. However, we identified a suitable drilling site with a undisturbed depth of at least 300m, which is deeper than the target depth of 200m for this site. Further post-processing will enhance the reflectors and will correct for surface topography.

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Fig. 9 Unprocessed ground penetrating radar profile from GIP showing proposed drill site in the centre of the image.

Fig. 9 Unprocessed ground penetrating radar profile from GIP showing proposed drill site in the centre of the image.

These images are used to create 3D model of bedrock topography (Fig.10) and/or individual isochrones to establish ice flow direction and shear stresses as well as geographical and temporal snow accumulation changes. This allows a comprehensive assessment of the suitability of the proposed drill site.

Fig. 10 Calculated bedrock topography at GIP showing proposed drill site in the centre of the image.

Fig. 10 Calculated bedrock topography at GIP showing proposed drill site in the centre of the image.

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Automatic Weather Station Data from Skinner Saddle and Evans Piedmont Glacier

The automatic weather station at SKS is operational since 01 Nov 2007. The recorded data for pressure, solar irradiation, air temperature, snow temperature, dew point, and snow accumulation for the time period of our deployment at SKS are shown in Fig.11.

Fig. 11: SKS automatic weather station data for 01 to 11 Nov 2007

Fig. 11: SKS automatic weather station data for 01 to 11 Nov 2007

Our weather station at EPG has been operational since October 2004. The current data set is shown in Fig. 12. The lack of data during winter 2005 is due to a technical failure.

Fig. 12: EPG automatic weather station data for Nov 2005 to Dec 2007

Fig. 12: EPG automatic weather station data for Nov 2005 to Dec 2007

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Physical snow properties at Victoria Lower Glacier

A shallow snow pit was investigated at VLG while we waited for our GPS mass balance measurements to be completed. The large seasonal temperature changes characteristic for this area produces some of the largest hoar (or cup) crystals on the planet.

Fig. 13: Cup crystals from Victoria Lower Glacier

Fig. 13: Cup crystals from Victoria Lower Glacier