Inter-annual snow accumulation and meter-scale variability from trench measurements at Dome C, Antarctica

Abstract

The central regions of the East Antarctic ice sheet contains some of the oldest ice on earth, due to low snow accumulation rates and consistently cold conditions. One consequence of low accumulation however is that the little snow amount which is deposited at irregular times is more strongly affected by erosion and re-deposition by wind, inducing local mixing and loss of snowfall events in the snowpack. This discontinuous deposition leads to highly disturbed snow layers, limiting the interpretation of climate records from ice cores in these regions to time scales larger than decades. In order to interpret climate records at higher temporal resolution it is crucial to assess and quantify the local patterns of snow accumulation leading to stratigraphic noise. Here, we reconstruct the spatial and temporal variability of snow accumulation in Central Antarctica using chemical composition and physical properties in 35 snow profiles in a 50 m long snow trench at Dome C. We show that a high resolution alignment of the chemistry profiles is a suitable method for inter-annual dating of the single trench profiles, allowing the reconstruction of accumulation time series with a 1 year resolution over the last 20 years. This reconstruction shows annually-varying past surface configurations, with up to 10 % of the surface subject to annual accumulation hiatus. More persistent multi-year scale patterns are also evidenced, causing difference in snow age of up to 4 years at similar depth in neighboring profiles, highlighting the complex dynamics of snow accumulation in central Antarctica.