Victoria Lower Glacier S77°19.810′, E162°31.991′

During the season 1999/2000 four shallow cores have recovered from the glacier (7.0m, 9.9m, 12.5m, 33.6m). While the 7.0m and 9.9m cores have been used to measure density profiles in the field, the 12.5 and 33.6m cores have been taken for further analyses to New Zealand and USA. All four cores have been logged to test for intrasite variability. The topography of the glacier surface in the vicinity of the drilling site has been surveyed applying differential GPS, with the base station employed at the Cape Roberts tide gauge.

To accomplish the ice/firn core record, snow profiles from 0 – 3m depth have been cut and investigated. The analyses include visual logging, density measurement and sampling for determining isotopic and chemistry characteristics. A mean annual temperature of −22.3°C has been calculated by recording the borehole temperatures of the 9.9 and 33.6m drilling holes (fig.).

Fig.2: Borehole temperature records from Victoria Lower Glacier and Baldwin Glacier

Continuous meteorological data, such as temperature, wind speed and direction and insolation, have been recorded and will help to correlate between longterm page 5 weather records from Marble Point and the actual weather systems at Victoria Lower Glacier, where no such records are available.

In order to determine the present-day state of mass balance, a 'coffee can' device has been installed, following the instructions of Hamilton & Whillans (1995). The first readings can be expected from the coming season onwards.

Investigations of the Lower Victoria Glacier snout indicated an overall positive mass balance and led to a better understanding of the general ice flow directions and catchment characteristics. The sand dunes, west of the glacier snout, have been studied as a possible source for the dust found in the cores.

Baldwin Valley Glacier S77°19.836′, E162°32.019′

Two firn cores have been recovered from Baldwin Glacier (12.2m and 31.1m). While the 12.2m core has been used to establish a density record, the longer core has been taken to NZ and USA for further analyses. A snow profile from 0 – 1.8m has been cut, visually logged and the density measured. Samples for iso-topic measurements and chemistry have been taken.

The mean annual air temperature was calculated to be −23°C by measuring borehole temperatures. Investigations of the vicinity of the drilling site gave insides of the ice flow structures and catchment characteristics.

Crary Laboratory

All cores chosen to be taken back for further analyses have been logged in more detail at Crary laboratory, using a light table. The 12.5m core from Victoria Lower Glacier has been prepared for ?-activity measurements and sent off. All cores have been split and packed for the transport to NZ and USA.

Methodology

• Ice Core Drilling

  For the ice core drilling the PICO (Polar Ice Coring Office) Hand Auger has been used. Despite the loss of one drilling bit, the coring went smoothly with only minor problems. A few modifications have been carried out for safety and convenience.

• Borehole Temperature Measurement

  Coupled conductivity wire were used to read temperature. The meter displayed a high sensitivity to the air temperature and had to be keptabove 0°C.

• Snow Profiling and Sampling

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  A hand saw and in places a chain saw were used to cut the snow profiles. No modifications were necessary.

• Meteorological Measurements

  The weather station used was hired from NIWA. Since it had been employed in Antarctica before, no modifications were necessary.

• Differential GPS Measurements

  The GPS system used (Trimble X PRO) has been employed in Antarctica before so that no modifications were necessary. In order to derive differential data, the measurements have been linked with the data from the base station located at the Cape Roberts tide gauge.