Abstract
Ocean/ice interaction at the base of deep-drafted Antarctic ice shelves modifies the physical properties of inflowing shelf waters to become Ice Shelf Water (ISW). In contrast to the conditions at the atmosphere/ocean interface, the increased hydrostatic pressure at the glacial base causes gases embedded in the ice to dissolve completely after being released by melting. Helium and neon, with an extremely low solubility, are saturated in glacial meltwater by more than 1000%. At the continental slope in front of the large Antarctic caverns, ISW mixes with ambient waters to form different precursors of Antarctic Bottom Water. A regional ocean circulation model, which uses an explicit formulation of the ocean/ice shelf interaction to describe for the first time the input of noble gases to the Southern Ocean, is presented. The results reveal a long-term variability of the basal mass loss solely controlled by the interaction between waters of the continental shelf and the ice shelf cavern. Modeled helium and neon supersaturations from the Filchner–Ronne Ice Shelf front show a “low-pass” filtering of the inflowing signal due to cavern processes. On circumpolar scales, the simulated helium and neon distributions allow us to quantify the ISW contribution to bottom water, which spreads with the coastal current connecting the major formation sites in Ross and Weddell Seas.
Similar content being viewed by others
Notes
Derived from bomb-produced radiocarbon invasion rates into the ocean and, hence, \(k_0\) includes implicitly the Schmidt number for \(^{14}{\rm C}\).
We assumed a constant total atmospheric pressure of 992.94 hPa \(\approx\) 0.97996 atm.
The uncertainty in the parameterization of the flux dependence to wind speed has probably a larger effect.
GMT (General Mapping Tool) topography is mainly based on the World Vector Shore data set of the National Geophysical Data Center in Boulder, CO, USA.
References
Asher W, Wanninkhof R (1998) Transient tracers and air–sea gas transfer. J Geophys Res 103(C8):15939–15958
Assmann K, Timmermann R (2005) Variability of dense water formation in the Ross Sea. Ocean Dyn 55(2):68–87
Baines P, Condie S (1998) Observations and modelling of Antarctic downslope flows: a review. In: Jacobs S, Weiss R (eds) Ocean, ice and atmosphere: interaction at the antarctic continental margin. Antarctic Research Series, vol. 75. American Geophysical Union, Washington, pp 29–49
Bayer R, Schlosser P (1991) Tritium profiles in the Weddell Sea. Mar Chem 35:123–136
Beckmann A, Hellmer H, Timmermann R (1999) A numerical model of the Weddell Sea: large scale circulation and water mass distribution. J Geophys Res 104(C10):23375–23391
Carmack E (1974) A quantitative characterization of water masses in the Weddell Sea during summer. Deep-Sea Res 21:431–443
England MH, Garcon V, Minster J-F (1994) Chlorofluorocarbon uptake in a world ocean model 1. Sensitivity to the surface gas forcing. J Geophys Res 99(C12):25215–25233
Foldvik A, Gammelsrød T, Tørrensen T (1985a) Hydrographic observations from the Weddell Sea during the Norwegian Antarctic research expedition 1976/77. Polar Res 3:177–193
Foldvik A, Gammelsrød T, Tørresen T (1985b) Circulation and water masses on the southern Weddell Sea shelf. In: Jacobs SS (ed) Oceanology of the Antarctic continental shelf. Antarctic Research Series, vol. 43. American Geophysical Union, Washington, pp 5–20
Foster T, Carmack E (1976) Frontal zone mixing and Antarctic bottom water formation in the southern Weddell Sea. Deep-Sea Res 23:301–317
Gade H (1979) Melting of ice in seawater: a primitive model with application to the Antarctic ice shelf and icebergs. J Phys Oceanogr 9:189–198
Gammelsrød T, Foldvik A, Nøst O, Skagseth Ø, Anderson L, Fogelqvist E, Olsson K, Tanhua T, Jones E, Østerhus S (1994) Distribution of water masses on the continental shelf in the southern Weddell Sea. In: The polar oceans and their role in shaping the global environment. Geophysical Monograph, vol. 84. American Geophysical Union, Washington, pp 159–176
Gerdes R, Determann J, Grosfeld K (1999) Ocean circulation beneath Filchner–Ronne Ice Shelf from three-dimensional model results. J Geophys Res 104(C7):15827–15842
Grosfeld K, Schröder M, Fahrbach E, Gerdes R, Mackensen A (2001) How iceberg calving and grouding change the circulation and hydrography in the Filchner Ice Shelf–Ocean System. J Geophys Res 106(C5):9039–9055
Haidvogel DB, Wilkin JL, Young R (1991) A semi-spectral primitive equation ocean circulation model using vertical sigma and orthogonal curvilinear horizontal coordinates. J Comput Phys 94(1):151–185
Hamme R, Emerson S (2002) Mechanisms controlling the global oceanic distribution of the inert gases: argon, nitrogen and neon. Geophys Res Lett 29(23):1–4
Hamme R, Emerson S (2004) The solubility of neon, nitrogen and argon in distilled water and seawater. Deep-Sea Res 51(11):1517–1528
Hellmer H (2004) Impact of Antarctic ice shelf melting on sea ice and deep ocean properties. Geophys Res Lett 31(10):28–29
Hellmer H, Olbers D (1989) A two-dimensional model for the thermohaline circulation under an ice shelf. Antarct Sci 1:325–336
Hohmann R, Schlosser P, Jacobs S, Ludin A, Weppernig R (2002) Excess helium and neon in the Southeast Pacific: tracers for glacial meltwater. J Geophys Res 107(C11):3198
Hood E (1997) Characterization of the air–sea gas exchange processes and dissolved gas/ice interaction using noble gases. Disseration, Massachusetts Institute of Technology/Woods Hole Oceanographic Institution, Cambridge, MA, USA
Hood E, Howes B, Jenkins W (1998) Dissolved gas dynamics in perennially ice-covered Lake Fryxell, Antarctica. Limnol Oceanogr 43(2):265–272
Jähne B, Heinz G, Dietrich W (1987) Measurement of the diffusion coefficients of sparingly soluble gases in water. J Geophys Res 92(C10):10767–10776
Joughin I, Padman L (2003) Melting and freezing beneath Filchner–Ronne Ice shelf, Antarctica. Geophys Res Lett 30(9):1477
Klatt O, Roether W, Hoppema M, Bulsiewicz K, Fleischmann U, Rodehacke C, Fahrbach E, Weiss R, Bullister J (2002) Repeated CFC sections at the Greenwich Meridian in the Weddell Sea. J Geophys Res 107(C4):43
Lewis E, Perkin R (1985) The winter oceanography of McMurdo Sound, Antartica. In: Jacobs S (ed) Oceanology of the Antarctic Continental Shelf. Antarctic Research Series, vol. 43. American Geophysical Union, Washington, pp 145–166
Mensch M, Bayer R, Bullister J, Schlosser P, Weiss R (1996) The distribution of tritium and CFCs in the Weddell Sea during the Mid 1980s. Prog Oceanogr 38:377–415
Nicholls K (1997) Predicted reduction in basal melt rates of an Antarctic ice shelf in a warmer climate. Nature 388:460–462
Nicholls K, Makinson K (1998) Ocean circulation beneath the Western Ronne Ice Shelf, as derived from in situ measurements of water currents and properties. In: Jacobs S, Weiss R (eds) Ocean, ice and atmosphere: interaction at the antarctic continental margin. Antarctic Research Series, vol. 75. American Geophysical Union, Washington, pp 301–318
Nøst O, Østerhus S (1998) Impact of grounded icebergs on the hydrographic conditions near the Filchner Ice Shelf. In: Ocean, ice and atmosphere: interaction at the Antarctic continental margin. Antarctic Research Series, vol. 75. American Geophysical Union, Washington, pp 267–284
Nicholls K, Østerhus S (2004) Interannual variability and ventilation time scales in the ocean cavity beneath Filchner–Ronne Ice Shelf, Antarctica. J Geophys Res 109(C04014)
Nicholls K, Padman L, Schrøder M, Woodgate R, Jenkins A, Østerhus S (2003) Water mass modification over the continental shelf north of Ronne Ice Shelf, Antarctica. J Geophys Res 108(C8):3260
Nowlin W Jr, Zenk W (1988) Westward bottom currents along the margin of the South Shetland Island Arc. Deep-Sea Res 35(2):269–301
Olbers D, Gouretski V, Seiß G, Schröter J (1992) Hydrographic atlas of the southern ocean. Technical report, Alfred-Wegener-Institut for Polar and Marine Science, Bremerhaven, Germany
Ozima M, Podosek F (1983) Noble gas geochemistry. Cambridge University Press, USA
Roether W, Well R, Putzka A, Rueth C (1998) Component separation of oceanic helium. J Geophys Res 103(C12):27931–27946
Roether W, Well R, Putzka A, Rueth C (2001) Corretion to “component separation of oceanic helium”. J Geophys Res 106(C3):4679
Schlosser P (1986) Helium: a new tracer in Antarctic oceanography. Nature 321:233–235
Schlosser P, Bayer R, Foldvik A, Gammelsrød T, Rohardt G, Münnich K (1990) Oxygen 18 and helium as tracers of ice shelf water and water/ice interaction in the Weddell Sea. J Geophys Res 95(C3):3253–3263
Schodlok M, Rodehacke C, Hellmer H, Beckmann A (2001) On the origin of the deep CFC maximum in the eastern Weddell Sea—numerical model results. Geophys Res Lett 28(14):2859–2862
Timmermann R, Beckmann A, Hellmer H (2002a) Simulations of ice–ocean dynamics in the Weddell Sea 1. Model configuration and validation. J Geophys Res 107(C3):101–109
Timmermann R, Hellmer H, Beckmann A (2002b) Simulations of ice–ocean dynamics in the Weddell Sea 2. Interannual variability 1985–1993. J Geophys Res 107(C3):111–116
Top Z, Eismont W, Clarke W (1987) Helium isotope effect and solubility of helium and neon in distilled water and seawater. Deep-Sea Res 34(7):1139–1148
Wanninkhof R (1992) Relationship between wind speed and gas exchange over the ocean. J Geophys Res 97(C5):7373–7382
Weiss R (1971) Solubility of helium and neon in water and seawater. J Chem Eng Data 16:235–241
Well R (1995) Analyse der Meßgüte eines massenspektrometrischen Meßsystems zur Heliumisotopen- und Neon-Bestimmung an Meerwasserproben. Disseration, Universität Bremen
Well R, Roether W (2003) Neon distribution in South Atlantic and South Pacific waters. Deep-Sea Res 50(6):721-735
White W, Peterson R (1996) An Antarctic circumpolar wave in surface pressure, wind, temperature and sea ice extent. Nature 380:699–702
Acknowledgements
We thank W. Roether and his former group at University Bremen for providing the noble gas data and supporting the completion of the manuscript in various ways. Thanks also to three reviewers, whose invaluable criticism helped to clarify and improve the manuscript. We thank R. Timmermann and C. Lichey for providing model forcing fields. C. Rodehacke thanks B. Klein and the team of the Institute for (Tracer) Oceanography at University of Bremen for their contribution to the data processing. This project was funded by the Deutsche Forschungsgemeinschaft (DFG) Nr. Ro 318/43 and the Alfred-Wegener-Institute contribution n15744.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible editor: John Wilkin
Rights and permissions
About this article
Cite this article
Rodehacke, C.B., Hellmer, H.H., Huhn, O. et al. Ocean/ice shelf interaction in the southern Weddell Sea: results of a regional numerical helium/neon simulation. Ocean Dynamics 57, 1–11 (2007). https://doi.org/10.1007/s10236-006-0073-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10236-006-0073-2