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Victoria University Antarctic Research Expedition Science and Logistics Reports 2005-06: VUWAE 50

d. Results and discussions

page 7

d. Results and discussions

The weather station has only recorded data from 15th Nov 2004 to 1st Jun 2005, when it stopped due to storage limitations but remained operating throughout the winter. The storage limitations have been addressed for future measurements. The recorded data for solar irradiation, air temperature, snow temperature, dew point, and snow accumulation are shown in below (Fig.7).

The time scale is in decimal years; months are indicated on top.

Fig. 7: Meteorological data collected at Evans Piedmont Glacier.

Fig. 7: Meteorological data collected at Evans Piedmont Glacier.

page 8

As shown in Fig.7 the decrease in solar irradiance from January to mid April is accompanied by cooling temperatures. Interestingly the temperature increases again from mid April until mid May before cooling once again. A higher frequency temperature variability is superimposed on this trend from mid February onwards with positive temperature deviations on a 4-6 day periodicity with an amplitude of up to 20K. The cause of these warm events could be katabatic outflow from the McKay Glacier portal. Due to the lack of barometric and wind data caused by hardware failure, we will use data from existing weather stations (e.g. Scott Base, Lake Vida, Terra Nova) and satellite imagery to investigate this pattern further. Temperatures in the snow pack measured concurrently at 16 depth horizons from 0.135m to 2.085m show the decreasing influence of air temperature variability with depth. While the temperature in the upper most horizon (starting at 13.5cm arriving in June at 43.5cm) ranges from −2°C to −30°C, at the deepest sensor (starting at 197.5cm arriving in June at 227.5cm) ranges from −17°C to −27°C. The snow temperatures have yet to be corrected for their change in depth, which increased by 30cm as shown in the snow accumulation graph below. The snow accumulation record shows that most of the precipitation occurred during three event of 5 to 15cm snow accumulation. The data show also that are no prolonged time periods of snow loss, except in the first 2-5 days after the snow precipitation event which is partly due to snow compaction. After this time period the snow surface remains stable. Overall, the data confirm EPG as an excellent ice core site. The snow pit data and submergence velocity measurements from EPG and VLG have yet to be processed.