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Overturning of the Antarctic Slope Front and glacial melting along the coast of Dronning Maud Land

Overturning of the Antarctic Slope Front and glacial melting along the coast of Dronning Maud Land. Ole Anders Nøst Martin Biuw, Christian Lydersen, Kit Kovacs, Qin Zhou and Vigdis Tverberg Norwegian Polar Institute. Elephant seals with CTD. The data.

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Overturning of the Antarctic Slope Front and glacial melting along the coast of Dronning Maud Land

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  1. Overturning of the Antarctic Slope Front and glacial melting along the coast of Dronning Maud Land Ole Anders Nøst Martin Biuw, Christian Lydersen, Kit Kovacs, Qin Zhou and Vigdis Tverberg Norwegian Polar Institute

  2. Elephant seals with CTD

  3. The data More than 1500 profiles within 100km of the coast/ice front The colors separate the different seals.

  4. The slope front and coastal current In this work we study the hydrographic conditions in the cold coastal waters above the thermocline. Thermocline Depth

  5. All data within 100km of the coast

  6. Daily averaged profiles plotted against time

  7. Monthly TS diagrams October TS-plot Red line: Mixing with WDW Blue line: Melting/ Freezing (Gade line) Glacial melting: Cold source waters and small salinity changes

  8. The development of salinity with time in the waters above the thermocline in a distance W=10km from the ice front/coast S – Depth averaged salinity SS – Surface salinity SW - Near bottom salinity

  9. Wind and surface heat fluxes calculated using NCEP and AMSR-E sea ice consentration

  10. Salinity as a result of Surface and bottom Ekman flow. Observations Model

  11. Q Salinity as a result of Surface and bottom Ekman flow. Sea ice formation Observations Model

  12. Q Salinity as a result of Surface and bottom Ekman flow. Sea ice formation Overturning of the ASF

  13. Glacial melting • 2000 km coastline, 100000km2 ice shelves • 1.5 Sv overturning with temperature 0.2oC above freezing. • Gives a melting of 1.4 m/year

  14. Conclusions • Hydrographic characteristics of the coastal current are given by a mix of surface water blown onshore and upwelled WDW. These are strongly mixed before interacting with ice shelves. • Low salinities are caused by summer meltwater blown onshore by the westward winds. Glacial melting has little influence on salinity in the coastal current. • Salinity increase during winter is mainly caused by overturning of the ASF, not sea ice formation. • The strong overturning of the ASF provides enough heat to melt ~1m/year from the base of the ice shelves.

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