EGU General Assembly 2020
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A recent update on the circulation and water masses around the Filchner and Ronne ice shelves in the southern Weddell Sea

Markus Janout1, Hartmut Hellmer1, Tore Hattermann2, Svein Osterhus3, Lucrecia Stulic1, Oliver Huhn4, Jürgen Sültenfuss4, and Torsten Kanzow1
Markus Janout et al.
  • 1Alfred-Wegener-Institute, Climate Sciences / Physical Oceanography, Bremerhaven, Germany (
  • 2Norwegian Polar Institute, Tromso, Norway
  • 3Norwegian Research Centre AS, Norway
  • 4University of Bremen, Germany

The Filchner and Ronne ice sheets (FRIS) compose the second largest contiguous ice sheet on the Antarctic continent. Unlike at several other Antarctic glaciers, basal melt rates at FRIS are comparatively low, as cold and dense waters presently dominate the wide southern Weddell Sea (WS) continental shelf and effectively block out any significant inflow of warmer ocean waters. We revisited the southern WS shelf in austral summer 2018 during Polarstern expedition PS111 with detailed hydrographic and tracer measurements along both the Ronne and Filchner ice fronts. The hydrography along FRIS was characterized by near-freezing high salinity shelf water (HSSW) in front of Ronne, and a striking dominance of ice shelf water (ISW) in Filchner Trough. The cold (-2.2°C) and fresher (34.6) ISW was formed by the interaction of Ronne-sourced HSSW with the ice shelf base. The strong dominance of ISW in Filchner Trough indicates a recently enhanced circulation below FRIS, likely fueled by enhanced sea ice production in the southwestern WS. We view these recent observations in a multidecadal (1973-present) context, contrast the two dominant circulation modes below FRIS, and discuss the importance of sea ice formation and large-scale sea level pressure patterns for the stability of the ocean circulation and basal melt rates underneath FRIS.

How to cite: Janout, M., Hellmer, H., Hattermann, T., Osterhus, S., Stulic, L., Huhn, O., Sültenfuss, J., and Kanzow, T.: A recent update on the circulation and water masses around the Filchner and Ronne ice shelves in the southern Weddell Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10194,, 2020

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