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Victoria University Antarctic Research Expedition Science and Logistics Reports 2004-05: VUWAE 49

Analyses of Snow Properties

Analyses of Snow Properties

At EPG and MES a 4m and 2m deep snow sequence was sampled at the drilling site prior to drilling to allow high resolution snow analysis. The snow profile was sampled with 1cm resolution for analysis on snow chemistry (Na, Ca, K, Mg, Cl, NO3, SO4, MS, Al, Fe, Si, Sr, Tr, Zn) and isotopic composition (δ18O and δD), dust content and mineralogy (Fig.6). This is necessary as the top 4m are usually of very low density, providing too little material to run high resolution analyses. Due to the unusually dense snow at MES, only the upper 2m were sampled. The data are used to establish transfer functions between meteorological records and the snow/ice core record, for temperature, precipitation, airmass origin, wind strength and direction, storm frequency, etc. The high sampling resolution provides sub-annual resolution of the climate record. At EPG additionally three snow pits were excavated to measure density and temperature of the snow pack and to study snow crystal structure and their geographical variability (Fig.7). This information is important to page 7 calculate annual accumulation rates and to evaluate the potential of re-crystallisation in the snow pack. Our initial results suggest excellent characteristics for ice core analyses. Annual layers did not show any sign of inclination or erosion and only 2 fine melt layers (<2mm) were found. This is particularly surprising, considering the coastal and low elevation (380m asl) setting of this site. The snow profile temperature showed the winter temperature wave travelling downwards in the snow pack. At the bottom of the profile the temperature touched upon the winter wave, reaching –33.6°C with a decreasing tendency.

Fig. 6: A) 4m deep snow pit at EPG, B) high resolution snow sampling

Fig. 6: A) 4m deep snow pit at EPG, B) high resolution snow sampling

The geographical variability of density, temperature and stratigraphy was small and within the limits of ±σ.

Fig. 7: A) Snow stratigraphy – annual layers are clearly visible, B) additional snow pit to measure geographic variability of snow density and temperature, C) double snow pit with snow wall in-between to study snow stratigraphy

Fig. 7: A) Snow stratigraphy – annual layers are clearly visible, B) additional snow pit to measure geographic variability of snow density and temperature, C) double snow pit with snow wall in-between to study snow stratigraphy