Density and stable oxygen isotope profiles of four snow pits from Berkner Island, Filchner-Ronne Ice Shelf, Antarctica

• Main Authors: Wagenbach, Dietmar, Graf, Wolfgang, Minikin, Andreas, Trefzer, Ulrich, Kipfstuhl, Sepp, Oerter, Hans, Blindow, Norbert
• Format: Dataset
• Language: English
• Published: PANGAEA 1994
• Subjects: AWI_Glac; BER01C90_01; BER01S90_01; BER02C90_02; BER02S90_02; Berkner Island (Reinwarthhöhe); Berkner Island (Thyssenhöhe); FBIN North-dome; FBIS South-dome; Filchner-Ronne-Ice-Shelf-Project; FIRN; Firn auger; FRISP 1992; Glaciology @ AWI; Sampling/drilling ice; SNOWPIT; Snow pit; SSBerkN North-dome; SSBerkS South-dome; Berkner Island; Reinwarthhöhe; Ronne Ice Shelf; Thyssenhöhe; Weddell; Weddell Sea; Annals of Glaciology; Antarc*; Antarctica; antartic*; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice cap; ice core; Ice Shelf
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.548752; https://doi.org/10.1594/PANGAEA.548752

The ice cap on Berkner Island is grounded on bedrock within the Filchner-Ronne Ice Shelf and is, therefore, expected to be a well-suited place to retrieve long-term ice-core records reflecting the environmental situation of the Weddell Sea region. Shallow firn cores were drilled to 11 m at the two main summits of Berkner Island and analysed in high depth resolution for electrical d.c. conductivity (ECM), stable isotopes, chloride, sulphate, nitrate and methane-sulphonate (MSA). From the annual layering of dD and non-sea-salt (nss) sulphate, a mean annual snow accumulation of 26.6 cm water at the north dome and 17.4 cm water at the south dome are obtained. As a result of ineffective wind scouring indicated by a relatively low near-surface snow density, regular annual cycles are found for all species at least in the upper 4-5 m. Post depositional changes are responsible for a substantial decrease of the seasonal dD and nitrate amplitude as well as for considerable migration of the MSA signal operating below a depth of 3-4 m. The mean chemical and isotopic firn properties at the south dome correspond to the situation on the Filchner-Ronne Ice shelf at a comparable distance to the coast, whereas the north dome is found to be more influenced by maritime air masses. Persistent high sea-salt levels in winter snow at Berkner Island heavily obscure the determination of nss sulphate probably due to sulphate fractionation in the Antartic sea-salt aerosols. Estimated time-scales predict ages at 400 m depth to be ca. 2000 years for the north and ca. 3000 years for the south dome. Pleistocene ice is expected in the bottom 200 and 300 m, respectively.