• Abrahamsen, E. P., , B. Hansen, , and C. Moore, 2003: GIANTS-RISOC cruise to the southeastern Weddell Sea on R.R.S. Shackleton. British Antarctic Survey Tech. Rep., 1–27 pp.

  • Årthun, M., , K. W. Nicholls, , K. Makinson, , M. A. Fedak, , and L. Boehme, 2012: Seasonal inflow of warm water onto the southern Weddell Sea continental shelf, Antarctica. Geophys. Res. Lett., 39, L17601, doi:10.1029/2012GL052856.

    • Search Google Scholar
    • Export Citation
  • Årthun, M., , K. W. Nicholls, , and L. Boehme, 2013: Wintertime water mass modification near an Antarctic Ice Front. J. Phys. Oceanogr., 43, 359365, doi:10.1175/JPO-D-12-0186.1.

    • Search Google Scholar
    • Export Citation
  • Boehme, L., , P. Lovell, , M. Biuw, , F. Roquet, , J. Nicholson, , S. E. Thorpe, , M. P. Meredith, , and M. Fedak, 2009: Technical note: Animal-borne CTD–satellite relay data loggers for real-time oceanographic data collection. Ocean Sci. Discuss., 6, 12611287, doi:10.5194/osd-6-1261-2009.

    • Search Google Scholar
    • Export Citation
  • Carmack, E. C., , and T. D. Foster, 1975: Circulation and distribution of oceanographic properties near the Filchner Ice Shelf. Deep-Sea Res. Oceanogr. Abstr., 22, 7790, doi:10.1016/0011-7471(75)90097-2.

    • Search Google Scholar
    • Export Citation
  • Darelius, E., 2013: Cruise ES060 with R.R.S. Ernest Shackleton. University of Bergen Geophysical Institute Tech. Rep., 33 pp.

  • Darelius, E., , and A. Wåhlin, 2007: Downward flow of dense water leaning on a submarine ridge. Deep-Sea Res. I, 54, 11731188, doi:10.1016/j.dsr.2007.04.007.

    • Search Google Scholar
    • Export Citation
  • Darelius, E., , L. H. Smedsrud, , S. Østerhus, , A. Foldvik, , and T. Gammelsrød, 2009: Structure and variability of the Filchner overflow plume. Tellus, 61, 446464, doi:10.1111/j.1600-0870.2009.00391.x.

    • Search Google Scholar
    • Export Citation
  • Fahrbach, E., , G. Rohardt, , N. Scheele, , M. Schröder, , V. Strass, , and A. Wisotzki, 1995: Formation and discharge of deep and bottom water in the northwestern Weddell Sea. J. Mar. Res., 53, 515538, doi:10.1357/0022240953213089.

    • Search Google Scholar
    • Export Citation
  • Fahrbach, E., , S. Harms, , G. Rohardt, , M. Schröder, , and R. A. Woodgate, 2001: Flow of bottom water in the northwestern Weddell Sea. J. Geophys. Res., 106 (C2), 27612778, doi:10.1029/2000JC900142.

    • Search Google Scholar
    • Export Citation
  • Foldvik, A., and et al. , 2004: Ice shelf water overflow and bottom water formation in the southern Weddell Sea. J. Geophys. Res.,109, C02015, doi:10.1029/2003JC002008.

  • Foster, T. D., , and E. C. Carmack, 1976: Frontal zone mixing and Antarctic Bottom Water formation in the southern Weddell Sea. Deep-Sea Res. Oceanogr., 23, 301317, doi:10.1016/0011-7471(76)90872-X.

    • Search Google Scholar
    • Export Citation
  • Gade, H., 1979: Melting of ice in sea water: A primitive model with application to the Antarctic Ice Shelf and icebergs. J. Phys. Oceanogr., 9, 189198, doi:10.1175/1520-0485(1979)009<0189:MOIISW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Gammelsrød, T., , and N. Slotsvik, 1981: Hydrographic and current measurements in the southern Weddell Sea 1979/80. Polarforschung, 51, 101111.

    • Search Google Scholar
    • Export Citation
  • Gammelsrød, T., and et al. , 1994: Distribution of water masses on the continental shelf in the southern Weddell Sea. The Polar Oceans and Their Role in Shaping the Global Environment, Geophys. Monogr., Vol. 85, Amer. Geophys. Union, 159–176.

  • Gill, A. E., 1973: Circulation and bottom water production in the Weddell Sea. Deep-Sea Res. Oceanogr. Abstr., 20, 111140, doi:10.1016/0011-7471(73)90048-X.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., 1998: Western Weddell Sea thermohaline stratification. Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin, Geophys. Monogr., Vol. 75, Amer. Geophys. Union, 215–240.

  • Gordon, A. L., , B. Huber, , D. C. McKee, , and M. Visbeck, 2010: A seasonal cycle in the export of bottom water from the Weddell Sea. Nat. Geosci., 3, 551556, doi:10.1038/ngeo916.

    • Search Google Scholar
    • Export Citation
  • Grosfeld, K., , M. Schröder, , E. Fahrbach, , R. Gerdes, , and A. Mackensen, 2001: How iceberg calving and grounding change the circulation and hydrography in the Filchner Ice Shelf–Ocean System. J. Geophys. Res., 106 (C5), 90399055, doi:10.1029/2000JC000601.

    • Search Google Scholar
    • Export Citation
  • Jenkins, A., 1999: The impact of melting ice on ocean waters. J. Phys. Oceanogr., 29, 23702381, doi:10.1175/1520-0485(1999)029<2370:TIOMIO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Jenkins, A., , D. M. Holland, , K. W. Nicholls, , M. Schröder, , and S. Østerhus, 2004: Seasonal ventilation of the cavity beneath Filchner–Ronne Ice Shelf simulated with an isopycnic coordinate ocean model. J. Geophys. Res.,109, C01024, doi:10.1029/2001JC001086.

  • Jensen, M. F., , I. Fer, , and E. Darelius, 2013: Low frequency variability on the continental slope of the southern Weddell Sea. J. Geophys. Res. Oceans, 118, 4256–4272, doi:10.1002/jgrc.20309.

    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., 2008: Quantifying Antarctic Bottom Water and North Atlantic Deep Water volumes. J. Geophys. Res.,113, C05027, doi:10.1029/2007JC004477.

  • Kida, S., 2011: The impact of open oceanic processes on the Antarctic Bottom Water outflows. J. Phys. Oceanogr., 41, 19411957, doi:10.1175/2011JPO4571.1.

    • Search Google Scholar
    • Export Citation
  • Lefebvre, W., 2004: Influence of the southern annular mode on the sea ice–ocean system. J. Geophys. Res.,109, C09005, doi:10.1029/2004JC002403.

  • McKee, D. C., , X. Yuan, , A. L. Gordon, , B. Huber, , and Z. Dong, 2011: Climate impact on interannual variability of Weddell Sea Bottom Water. J. Geophys. Res.,116, C05020, doi:10.1029/2010JC006484.

  • Meredith, M. P., 2013: Replenishing the abyss. Nat. Geosci., 6, 166167, doi:10.1038/ngeo1743.

  • Nicholls, K. W., , and S. Østerhus, 2004: Interannual variability and ventilation timescales in the ocean cavity beneath Filchner–Ronne Ice Shelf, Antarctica. J. Geophys. Res., 109 (C4), C04014, doi:10.1029/2003JC002149.

    • Search Google Scholar
    • Export Citation
  • Nicholls, K. W., , S. Østerhus, , K. Makinson, , and M. R. Johnson, 2001: Oceanographic conditions south of Berkner Island, beneath Filchner–Ronne Ice Shelf, Antarctica. J. Geophys. Res., 106 (C6), 11 48111 492, doi:10.1029/2000JC000350.

    • Search Google Scholar
    • Export Citation
  • Nicholls, K. W., , S. Østerhus, , K. Makinson, , T. Gammelsrød, , and E. Fahrbach, 2009: Ice-ocean processes over the continental shelf of the southern Weddell Sea, Antarctica: A review. Rev. Geophys., 47, RG3003, doi:10.1029/2007RG000250.

    • Search Google Scholar
    • Export Citation
  • Nøst, O. A., , S. Østerhus, , and A. Nøst, 1998: Impact of grounded icebergs on the hydrographic conditions near the Filchner Ice Shelf. Ocean, Ice, and Atmosphere: Interaction at the Antarctic Continental Margin, Geophys. Monogr., Vol. 75, Amer. Geophys. Union, 267–284.

  • Ohshima, K. I., and et al. , 2013: Antarctic Bottom Water production by intense sea-ice formation in the Cape Darnley Polynya. Nat. Geosci., 6, 235240, doi:10.1038/ngeo1738.

    • Search Google Scholar
    • Export Citation
  • Schlosser, P., , R. Bayer, , A. Foldvik, , T. Gammelsrød, , G. Rohardt, , and K. O. Munnich, 1990: Oxygen 18 and helium as tracers of ice shelf water and water ice interaction in the Weddell Sea. J. Geophys. Res., 95 (C3), 32533263, doi:10.1029/JC095iC03p03253.

    • Search Google Scholar
    • Export Citation
  • Strand, K. O., 2011: Variations of the ice shelf water in the southern Weddell Sea, Antarctica. M. S. thesis, Geophysical Institute, University of Bergen, 59 pp.

  • Sverdrup, H., 1954: The currents off the coast of Queen Maud Land. Nor. Geogr. Tidsskr., 14 (1), 239249, doi:10.1080/00291955308542731.

    • Search Google Scholar
    • Export Citation
  • Timmermann, R., , H. H. Hellmer, , and A. Beckmann, 2002: Simulations of ice-ocean dynamics in the Weddell Sea 2. Interannual variability 1985–1993. J. Geophys. Res., 107 (C3), doi:10.1029/2000JC000742.

    • Search Google Scholar
    • Export Citation
  • Wang, Q., , S. Danilov, , E. Fahrbach, , J. Schröter, , and T. Jung, 2012: On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport. Geophys. Res. Lett., 39, L06603, doi:10.1029/2012GL051198.

    • Search Google Scholar
    • Export Citation
  • Weppernig, R., , P. Schlosser, , S. Khatiwala, , and R. G. Fairbanks, 1996: Isotope data from Ice Station Weddell: Implications for deep water formation in the Weddell Sea. J. Geophys. Res., 101 (C11), 25 723–25 739, doi:10.1029/96JC01895.

    • Search Google Scholar
    • Export Citation
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On the Seasonal Signal of the Filchner Overflow, Weddell Sea, Antarctica

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  • 1 * Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway
  • | 2 Norwegian Meteorological Institute, Bergen, Norway
  • | 3 Uni Climate, Uni Research, and Bjerknes Centre for Climate Research, Bergen, Norway
  • | 4 British Antarctic Survey, Cambridge, United Kingdom
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Abstract

The cold ice shelf water (ISW) that formed below the Filchner–Ronne Ice Shelf in the southwestern Weddell Sea, Antarctica, escapes the ice shelf cavity through the Filchner Depression and spills over its sill at a rate of 1.6 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1), thus contributing significantly to the production of Weddell Sea Bottom Water. Here, the authors examine all available observational data from the region—including five year-long time series of mooring data from the Filchner sill—to examine the seasonal variability of the outflow. The temperature of the ISW outflow is found to vary seasonally by 0.07°C with a maximum in April. The accompanying signal in salinity causes a seasonal signal in density of 0.03–0.04 kg m−3, potentially changing the penetration depth of the ISW plume by more than 500 m. Contrary to recent modeling, the observations show no seasonal variability in outflow velocity. The seasonality observed at the sill is, at least partly, due to the admixture of high-salinity shelf water from the Berkner Bank. Observations and numerical modeling suggest, however, seasonal signals in the circulation upstream (i.e., in the ice shelf cavity and in the Filchner Depression) that—although processes and linkages are unclear—are likely to contribute to the seasonal signal observed at the sill. In the plume region downstream of the sill, the source variability is apparent only within the very densest portions of the ISW plume. In the more diluted part of the plume, the source variability is overcome by the seasonality in the properties of the water entrained at the shelf break. This will have implications for the properties of the generated bottom waters.

Corresponding author address: E. Darelius, Geophysical Institute, University of Bergen, Alleg. 70, 5007 Bergen, Norway. E-mail: darelius@gfi.uib.no

Abstract

The cold ice shelf water (ISW) that formed below the Filchner–Ronne Ice Shelf in the southwestern Weddell Sea, Antarctica, escapes the ice shelf cavity through the Filchner Depression and spills over its sill at a rate of 1.6 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1), thus contributing significantly to the production of Weddell Sea Bottom Water. Here, the authors examine all available observational data from the region—including five year-long time series of mooring data from the Filchner sill—to examine the seasonal variability of the outflow. The temperature of the ISW outflow is found to vary seasonally by 0.07°C with a maximum in April. The accompanying signal in salinity causes a seasonal signal in density of 0.03–0.04 kg m−3, potentially changing the penetration depth of the ISW plume by more than 500 m. Contrary to recent modeling, the observations show no seasonal variability in outflow velocity. The seasonality observed at the sill is, at least partly, due to the admixture of high-salinity shelf water from the Berkner Bank. Observations and numerical modeling suggest, however, seasonal signals in the circulation upstream (i.e., in the ice shelf cavity and in the Filchner Depression) that—although processes and linkages are unclear—are likely to contribute to the seasonal signal observed at the sill. In the plume region downstream of the sill, the source variability is apparent only within the very densest portions of the ISW plume. In the more diluted part of the plume, the source variability is overcome by the seasonality in the properties of the water entrained at the shelf break. This will have implications for the properties of the generated bottom waters.

Corresponding author address: E. Darelius, Geophysical Institute, University of Bergen, Alleg. 70, 5007 Bergen, Norway. E-mail: darelius@gfi.uib.no
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