A glaciochemical study of 120 m ice core from Mill Island, East
Mana Inoue1,2, Mark A. J. Curran1,3, Andrew D. Moy1,3, Tas D. van Ommen1,3, Alexander D. Fraser1,4, Helen E. Phillips2, and Ian D. Goodwin51Antarctic Climate & Ecosystems Cooperate Research Centre, Private Bag 80, University of Tasmania, Hobart, Tasmania 7005, Australia 2Institute for Marine & Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia 3Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia 4Institute of Low Temperature Science, Hokkaido University, N19, W8, Kita-ku Sapporo 060-0819, Japan 5Marine Climate Risk Group, Department of Environment and Geography, Macquarie University, Eastern Road, New South Wales 2109, Australia
Received: 27 Jun 2016 – Accepted for review: 06 Sep 2016 – Discussion started: 15 Sep 2016
Abstract. A 120 m ice core was drilled on Mill Island, East Antarctica (65°30’ S, 100°40’ E) during the 2009/2010 Australian Antarctic field season. Contiguous discrete 5 cm samples were measured for hydrogen peroxide, water stable isotopes and trace ion chemistry. The ice core was annually dated using a combination of chemical species and water stable isotopes. The Mill Island ice core preserves a climate record covering 97 years from 1913 to 2009 C.E., with a mean snow accumulation of 1.35 m (ice-equivalent) per year (mIE yr−1). This northernmost East Antarctic coastal ice core site displays trace ion concentrations that are generally higher than other Antarctic ice core sites (e.g., mean sodium levels were 254 μEq L−1). The trace ion record at Mill Island is characterised by a unique and complex chemistry record with three distinct regimes identified. The trace ion record in Regime A displays clear seasonality from 2000 to 2009 C.E.; Regime B displays elevated concentrations with no seasonality from 1934 to 2000 C.E.; and Regime C displays relatively low concentrations with seasonality from 1913 to 1934 C.E. Sea salts were compared with instrumental data, including atmospheric models and satellite-derived sea ice concentration, to investigate influences on the Mill Island ice core record. The mean annual sea salt record does not correlate with wind speed. Instead, sea ice concentration to the east of Mill Island likely influences the annual mean sea salt record. A mechanism involving formation of frost flowers on sea ice is proposed to explain the extremely high sea salt concentration. The Mill Island ice core records are unexpectedly complex, with strong modulation of the trace chemistry on long timescales.
Inoue, M., Curran, M. A. J., Moy, A. D., van Ommen, T. D., Fraser, A. D., Phillips, H. E., and Goodwin, I. D.: A glaciochemical study of 120 m ice core from Mill Island, East
Antarctica, Clim. Past Discuss., doi:10.5194/cp-2016-72, in review, 2016.