15 Nov 2022
15 Nov 2022
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Climatology of the Mount Brown South ice core site in East Antarctica: implications for the interpretation of a water isotope record

Sarah Louise Jackson1,2,3, Tessa R. Vance4, Camilla Crockart4, Andrew Moy5,4, Christopher Plummer4, and Nerilie J. Abram1,2,3 Sarah Louise Jackson et al.
  • 1Research. School of Earth Sciences, Australian National University, Canberra ACT 2601, Australia
  • 2Australian Centre for Excellence in Antarctic Science, Australian National University, Canberra ACT 2601, Australia
  • 3ARC Centre of Excellence for Climate Extremes, Australian National University, Canberra ACT 2601, Australia
  • 4Australian Antarctic Program Partnership, Institute for Marine & Antarctic Studies, University of Tasmania, Hobart TAS 7004, Australia
  • 5Australian Antarctic Division, Department of Climate Change, Energy, the Environment and Water, Kingston TAS 7050, Australia

Abstract. Water stable isotope records from ice cores (δ18O and δD) are a critical tool for constraining long-term temperature variability in the high-latitudes. However, precipitation in Antarctica consists of semi-continuous small events and intermittent extreme events. In regions of high-accumulation, this can bias ice core records towards recording the synoptic climate conditions present during extreme precipitation events. In this study we utilise a combination of ice core data, re-analysis products and models to understand how precipitation intermittency impacts the temperature records preserved in an ice core from Mount Brown South in East Antarctica. Extreme precipitation events represent only the largest 10 % of all precipitation events, but they account for 44 % of the total annual snowfall at this site leading to an over-representation of these events in the ice core record. Extreme precipitation events are associated with high-pressure systems in the mid-latitudes which cause increased transport of warm and moist air from the southern Indian Ocean to the ice core site. Warm temperatures associated with these events result in a +2.8 °C warm bias in the mean annual temperature when weighted by daily precipitation, and water isotopes in the Mount Brown South ice core are shown to be significantly correlated with local temperature when this precipitation-induced temperature bias is included. The Mount Brown South water isotope record spans more than 1000 years and will provide a valuable regional reconstruction of long-term temperature and hydroclimate variability in the data-sparse southern Indian Ocean region.

Sarah Louise Jackson et al.

Status: open (until 10 Jan 2023)

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Sarah Louise Jackson et al.

Sarah Louise Jackson et al.


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Short summary
Ice core records are useful tools for reconstructing past climate. However, ice cores favour recording climate conditions at times when snowfall occurs. Large snowfall events in Antarctica are often associated with warmer-than-usual temperatures. We show that this results in a tendency for the Mount Brown South ice core record to preserve a temperature record with a warm bias.