Decadal Freshening of the Antarctic Bottom Water Exported from the Weddell Sea

Loïc Jullion National Oceanography Centre, University of Southampton, Southampton, United Kingdom

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Alberto C. Naveira Garabato National Oceanography Centre, University of Southampton, Southampton, United Kingdom

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Michael P. Meredith British Antarctic Survey, Cambridge, and Scottish Association for Marine Science, Oban, United Kingdom

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Paul R. Holland British Antarctic Survey, Cambridge, United Kingdom

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Peggy Courtois National Oceanography Centre, University of Southampton, Southampton, United Kingdom

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Brian A. King National Oceanography Centre, Southampton, United Kingdom

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Abstract

Recent decadal changes in Southern Hemisphere climate have driven strong responses from the cryosphere. Concurrently, there has been a marked freshening of the shelf and bottom waters across a wide sector of the Southern Ocean, hypothesized to be caused by accelerated glacial melt in response to a greater flux of warm waters from the Antarctic Circumpolar Current onto the shelves of West Antarctica. However, the circumpolar pattern of changes has been incomplete: no decadal freshening in the deep layers of the Atlantic sector has been observed. In this study, the authors document a significant freshening of the Antarctic Bottom Water exported from the Weddell Sea, which is the source for the abyssal layer of the Atlantic overturning circulation, and trace its possible origin to atmospheric-forced changes in the ice shelves and sea ice on the eastern flank of the Antarctic Peninsula that include an anthropogenic component. These findings suggest that the expansive and relatively cool Weddell gyre does not insulate the bottom water formation regions in the Atlantic sector from the ongoing changes in climatic forcing over the Antarctic region.

Current affiliation: Geophysical Fluid Dynamics Institute, The Florida State University, Tallahassee, Florida.

Corresponding author address: Loïc Jullion, Geophysical Fluid Dynamics Institute, The Florida State University, Tallahassee, FL 32306. E-mail: l.jullion@fsu.edu

Abstract

Recent decadal changes in Southern Hemisphere climate have driven strong responses from the cryosphere. Concurrently, there has been a marked freshening of the shelf and bottom waters across a wide sector of the Southern Ocean, hypothesized to be caused by accelerated glacial melt in response to a greater flux of warm waters from the Antarctic Circumpolar Current onto the shelves of West Antarctica. However, the circumpolar pattern of changes has been incomplete: no decadal freshening in the deep layers of the Atlantic sector has been observed. In this study, the authors document a significant freshening of the Antarctic Bottom Water exported from the Weddell Sea, which is the source for the abyssal layer of the Atlantic overturning circulation, and trace its possible origin to atmospheric-forced changes in the ice shelves and sea ice on the eastern flank of the Antarctic Peninsula that include an anthropogenic component. These findings suggest that the expansive and relatively cool Weddell gyre does not insulate the bottom water formation regions in the Atlantic sector from the ongoing changes in climatic forcing over the Antarctic region.

Current affiliation: Geophysical Fluid Dynamics Institute, The Florida State University, Tallahassee, Florida.

Corresponding author address: Loïc Jullion, Geophysical Fluid Dynamics Institute, The Florida State University, Tallahassee, FL 32306. E-mail: l.jullion@fsu.edu
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  • Aoki, S., S. Rintoul, S. Ushio, S. Watanabe, and N. Bindoff, 2005: Freshening of the Adélie Land Bottom Water near 140°E. Geophys. Res. Lett.,32, L23601, doi:10.1029/2005GL024246.

  • Bacon, S., H. Snaith, and M. Yelland, 2000: An evaluation of some recent batches of IAPSO standard seawater. J. Atmos. Oceanic Technol., 17, 854861.

    • Search Google Scholar
    • Export Citation
  • Bacon, S., F. Culkin, N. Higgs, and P. Ridout, 2007: IAPSO standard seawater: Definition of the uncertainty in the calibration procedure, and stability of recent batches. J. Atmos. Oceanic Technol., 24, 17851799.

    • Search Google Scholar
    • Export Citation
  • Behrendt, A., E. Fahrbach, M. Hoppema, G. Rohardt, O. Boebel, O. Klatt, A. Wisotzki, and H. Witte, 2011: Variations of winter water properties and sea ice along the Greenwich meridian on decadal time scales. Deep-Sea Res. II, 58, 25242532, doi:10.1016/j.dsr2.2011.07.001.

    • Search Google Scholar
    • Export Citation
  • Berthier, E., T. A. Scambos, and C. A. Shuman, 2012: Mass loss of Larsen B tributary glaciers (Antarctic Peninsula) unabated since 2002. Geophys. Res. Lett.,39, L13501, doi:10.1029/2012GL051755.

  • Bromwich, D. H., J. P. Nicolas, and A. J. Monaghan, 2011: An assessment of precipitation changes over Antarctica and the Southern Ocean since 1989 in contemporary global reanalyses. J. Climate, 24, 41894209.

    • Search Google Scholar
    • Export Citation
  • Carmack, E., and T. Foster, 1975: Flow of water out of the Weddell Sea. Deep-Sea Res., 22, 711724.

  • Cavalieri, D., C. Parkinson, P. Gloersen, and H. J. Zwally, 1996: Sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS passive microwave data. National Snow and Ice Data Center, Boulder, CO, digital media. [Available online at http://nsidc.org/data/docs/daac/nsidc0051_gsfc_seaice.gd.html.]

  • Church, J. A., and Coauthors, 2011: Revisiting the Earth's sea-level and energy budgets from 1961 to 2008. Geophys. Res. Lett.,38, L18601, doi:10.1029/2011GL048794.

  • Eicken, H., 1997: Salinity profiles of Antarctic sea ice: Field data and model results. J. Geophys. Res., 97 (C10), 15 54515 557.

  • 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.

    • Search Google Scholar
    • Export Citation
  • Fahrbach, E., M. Hoppema, G. Rohardt, O. Boebel, O. Klatt, and A. Wisotzki, 2011: Warming of deep and abyssal water masses along the Greenwich meridian on decadal time scales the Weddell Gyre as a heat buffer. Deep-Sea Res. II, 58, 25092523, doi:10.1016/j.dsr2.2011.06.007.

    • Search Google Scholar
    • Export Citation
  • Foldvik, A., and Coauthors, 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., and E. Carmack, 1976: Frontal zone mixing and Antarctic Bottom Water formation in the southern Weddell Sea. Deep-Sea Res., 23, 301317.

    • Search Google Scholar
    • Export Citation
  • Fricker, H. A., and L. Padman, 2012: Thirty years of elevation change on Antarctic peninsula ice shelves from multimission satellite radar altimetry. J. Geophys. Res.,117, C02026, doi:10.1029/2011JC007126.

  • Gill, A., 1973: Circulation and bottom water production in the Weddell Sea. Deep-Sea Res., 20, 111140.

  • Gordon, A. L., M. Visbeck, and B. Huber, 2001: Export of Weddell Sea deep and bottom water. J. Geophys. Res., 106 (C5), 90059017.

  • Gordon, A. L., B. Huber, D. 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
  • Gouretski, V., and K. Jancke, 2000: Systematic errors as the cause for an apparent deep water property variability: Global analysis of the WOCE and historical hydrographic data. Prog. Oceanogr., 48, 337402.

    • Search Google Scholar
    • Export Citation
  • Hellmer, H. H., O. Huhn, D. Gomis, and R. Timmermann, 2011: On the freshening of the northwestern Weddell Sea continental shelf. Ocean Sci., 7, 305316, doi:10.5194/os-7-305-2011.

    • Search Google Scholar
    • Export Citation
  • Hellmer, H. H., F. Kauker, R. Timmermann, J. Determann, and J. Rae, 2012: Twenty-first-century warming of a large Antarctic ice-shelf cavity by a redirected coastal current. Nature, 485, 225228, doi:10.1038/nature11064.

    • Search Google Scholar
    • Export Citation
  • Holland, P. R., H. F. J. Corr, H. D. Pritchard, D. G. Vaughan, R. J. Arthern, A. Jenkins, and M. Tedesco, 2011: The air content of Larsen ice shelf. Geophys. Res. Lett.,38, L10503, doi:10.1029/2011GL047245.

  • Huhn, O., H. H. Hellmer, M. Rhein, C. Rodehacke, W. Roether, M. Schodlok, and M. Schroder, 2008: Evidence of deep-and bottom-water formation in the western Weddell Sea. Deep-Sea Res. II, 55, 10981116.

    • Search Google Scholar
    • Export Citation
  • Jackett, D., and T. McDougall, 1997: A neutral density variable for the world's oceans. J. Phys. Oceanogr., 27, 237263.

  • Jacobs, S. S., 2004: Bottom water production and its links with the thermohaline circulation. Antarct. Sci., 16, 427437, doi:10.1017/S095410200400224X.

    • Search Google Scholar
    • Export Citation
  • Jacobs, S. S., and C. F. Giulivi, 2010: Large multidecadal salinity trends near the Pacific Antarctic continental margin. J. Climate, 23, 45084524.

    • Search Google Scholar
    • Export Citation
  • Jacobs, S. S., C. F. Giulivi, and P. Mele, 2002: Freshening of the Ross Sea during the late 20th century. Science, 297, 386389.

  • Jacobs, S. S., A. Jenkins, C. F. Giulivi, and P. Dutrieux, 2011: Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nat. Geosci., 4, 519523, doi:10.1038/ngeo1188.

    • Search Google Scholar
    • Export Citation
  • Jansen, D., M. Schodlok, and W. Rack, 2007: Basal melting of A-38b: A physical model constrained by satellite observations. Remote Sens. Environ., 111, 195203.

    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., and S. C. Doney, 2006: Recent western South Atlantic bottom water warming. Geophys. Res. Lett.,33, L14614, doi:10.1029/2006GL026769.

  • Johnson, G. C., S. G. Purkey, and J. L. Bullister, 2008a: Warming and freshening in the abyssal southeastern Indian Ocean. J. Climate, 21, 53515363.

    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., S. G. Purkey, and J. M. Toole, 2008b: Reduced Antarctic meridional overturning circulation reaches the North Atlantic Ocean. Geophys. Res. Lett.,35, L22601, doi:10.1029/2008GL035619.

  • Jullion, L., S. C. Jones, A. C. N. Garabato, and M. P. Meredith, 2010: Wind-controlled export of Antarctic Bottom Water from the Weddell Sea. Geophys. Res. Lett.,37, L09609, doi:10.1029/2010GL042822.

  • Kawano, T., M. Aoyama, T. Joyce, H. Uchida, Y. Takatsuki, and M. Fukasawa, 2006: The latest batch-to-batch difference table of standard seawater and its application to the WOCE onetime sections. J. Oceanogr., 62, 777792.

    • Search Google Scholar
    • Export Citation
  • Killworth, P., 1974: Baroclinic model of motions on antarctic continental shelves. Deep-Sea Res., 21, 815837.

  • King, J., J. Turner, G. Marshall, W. Connolley, and T. Lachlan-Cope, 2004: Antarctic Peninsula climate variability and its causes as revealed by analysis of instrumental records. Antarctic Peninsula Climate Variability: A Historical and Paleoenvironmental Perspective, E. Domack et al., Eds., Antarctic Research Series, Vol. 79, Amer. Geophys. Union, 17–30.

  • MacAyeal, D., T. Scambos, C. Hulbe, and M. Fahnestock, 2003: Catastrophic ice-shelf break-up by an ice-shelf-fragment-capsize mechanism. J. Glaciol., 49, 2236.

    • Search Google Scholar
    • Export Citation
  • Mantyla, A., 1980: Electric conductivity comparisons of standard seawater batches P29 to P84. Deep-Sea Res., 27A, 837846.

  • Mantyla, A., 1987: Standard seawater comparisons updated. J. Phys. Oceanogr., 17, 543548.

  • Mantyla, A., 1994: The treatment of inconsistencies in Atlantic deep water salinity data. Deep-Sea Res., 41, 13871405.

  • Marshall, G. J., P. A. Stott, J. Turner, W. M. Connolley, J. C. King, and T. A. Lachlan-Cope, 2004: Causes of exceptional atmospheric circulation changes in the Southern Hemisphere. Geophys. Res. Lett.,31, L14205, doi:10.1029/2004GL019952.

  • Marshall, G. J., A. Orr, N. P. M. van Lipzig, and J. King, 2006: The impact of a changing Southern Hemisphere annular mode on Antarctic Peninsula summer temperatures. J. Climate, 19, 53885404.

    • Search Google Scholar
    • Export Citation
  • Maslanik, J., 1999: Near-real-time DMSP SSM/I-SSMIS daily polar gridded sea ice concentrations. National Snow and Ice Data Center, Boulder, CO, digital media. [Available online at http://nsidc.org/data/docs/daac/nsidc0081_ssmi_nrt_seaice.gd.html.]

  • Meredith, M. P., R. Locarnini, K. V. Scoy, A. Watson, K. Heywood, and B. King, 2000: On the sources of Weddell Gyre Antarctic Bottom Water. J. Geophys. Res., 105 (C1), 10931104.

    • Search Google Scholar
    • Export Citation
  • Meredith, M. P., A. C. Naveira Garabato, A. L. Gordon, and G. C. Johnson, 2008: Evolution of the deep and bottom waters of the Scotia Sea, Southern Ocean, during 1995–2005. J. Climate, 21, 33273343.

    • Search Google Scholar
    • Export Citation
  • Meredith, M. P., A. L. Gordon, A. C. N. Garabato, E. P. Abrahamsen, B. A. Huber, L. Jullion, and H. J. Venables, 2011: Synchronous intensification and warming of Antarctic Bottom Water outflow from the Weddell Gyre. Geophys. Res. Lett.,38, L03603, doi:10.1029/2010GL046265.

  • Munneke, P. K., G. Picard, M. R. V. D. Broeke, J. T. M. Lenaerts, and E. V. Meijgaard, 2012: Insignificant change in Antarctic snowmelt volume since 1979. Geophys. Res. Lett.,39, L01501, doi:10.1029/2011GL050207.

  • Naveira Garabato, A. C., K. J. Heywood, and D. P. Stevens, 2002a: Modification and pathways of Southern Ocean deep waters in the Scotia Sea. Deep-Sea Res. I, 49, 681705.

    • Search Google Scholar
    • Export Citation
  • Naveira Garabato, A. C., E. McDonagh, D. P. Stevens, K. J. Heywood, and R. J. Sanders, 2002b: On the export of Antarctic Bottom Water from the Weddell Sea. Deep-Sea Res. II, 49, 47154742.

    • Search Google Scholar
    • Export Citation
  • Naveira Garabato, A. C., K. L. Polzin, B. King, K. J. Heywood, and M. Visbeck, 2004: Widespread intense turbulent mixing in the Southern Ocean. Science, 303, 210213.

    • Search Google Scholar
    • Export Citation
  • Naveira Garabato, A. C., L. Jullion, D. P. Stevens, K. J. Heywood, and B. A. King, 2009: Variability of Subantarctic Mode Water and Antarctic Intermediate Water in the Drake Passage during the late-twentieth and early-twenty-first century. J. Climate, 22, 36613688.

    • 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.

  • Nowlin, W., Jr., and W. Zenk, 1988: Westward bottom currents along the margin of the south Shetland Island arc. Deep-Sea Res. I, 35, 269301.

    • Search Google Scholar
    • Export Citation
  • Orr, A., D. Cresswell, G. J. Marshall, J. Hunt, J. Sommeria, C. Wang, and M. Light, 2004: A ‘low-level'explanation for the recent large warming trend over the western Antarctic Peninsula involving blocked winds and changes in zonal circulation. Geophys. Res. Lett.,31, L06204, doi:10.1029/2003GL019160.

  • Orsi, A., T. Whitworth, and W. D. Nowlin, 1995: On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Res. I, 42, 641673.

    • Search Google Scholar
    • Export Citation
  • Orsi, A., G. C. Johnson, and J. L. Bullister, 1999: Circulation, mixing, and production of Antarctic Bottom Water. Prog. Oceanogr., 43, 55109.

    • Search Google Scholar
    • Export Citation
  • Pritchard, H. D., S. R. M. Ligtenberg, H. A. Fricker, D. G. Vaughan, M. R. van den Broeke, and L. Padman, 2012: Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature, 484, 502505, doi:10.1038/nature10968.

    • Search Google Scholar
    • Export Citation
  • Provost, C., A. Renault, N. Barré, N. Sennéchael, V. Garçon, J. Sudre, and O. Huhn, 2011: Two repeat crossings of Drake Passage in austral summer 2006 short-term variations and evidence for considerable ventilation of intermediate and deep waters. Deep-Sea Res. II, 58, 25552571.

    • Search Google Scholar
    • Export Citation
  • Purkey, S. G., and G. C. Johnson, 2010: Warming of global abyssal and deep southern ocean waters between the 1990s and 2000s: Contributions to global heat and sea level rise budgets. J. Climate, 23, 63366351.

    • Search Google Scholar
    • Export Citation
  • Purkey, S. G., and G. C. Johnson, 2012: Global contraction of Antarctic Bottom Water between the 1980s and 2000s. J. Climate, 25, 58305844.

    • Search Google Scholar
    • Export Citation
  • Rack, W., and H. Rott, 2004: Pattern of retreat and disintegration of the Larsen B ice shelf, Antarctic Peninsula. Ann. Glaciol., 39, 505510.

    • Search Google Scholar
    • Export Citation
  • Rignot, E., 2006: Changes in ice dynamics and mass balance of the Antarctic ice sheet. Philos. Trans. Roy. Soc., A364, 16371655, doi:10.1098/rsta.2006.1793.

    • Search Google Scholar
    • Export Citation
  • Rignot, E., G. Casassa, P. Gogineni, W. Krabill, A. Rivera, and R. Thomas, 2004: Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf. Geophys. Res. Lett.,31, L18401, doi:10.1029/2004GL020697.

  • Rintoul, S. R., 2007: Rapid freshening of Antarctic Bottom Water formed in the Indian and Pacific Oceans. Geophys. Res. Lett.,34, L06606, doi:10.1029/2006GL028550.

  • Roemmich, D., G. Johnson, S. Riser, R. Davis, J. Gilson, W. Owens, C. Schmid, and M. Ignaszewski, 2009: The Argo program: Observing the global oceans with profiling floats. Oceanography, 22, 2433.

    • Search Google Scholar
    • Export Citation
  • Rott, H., P. Skvarca, and T. Nagler, 1996: Rapid collapse of northern Larsen ice shelf, Antarctica. Science, 271, 788792, doi:10.1126/science.271.5250.788.

    • Search Google Scholar
    • Export Citation
  • Rott, H., F. Müller, T. Nagler, and D. Floricioiu, 2011: The imbalance of glaciers after disintegration of Larsen-B ice shelf, Antarctic Peninsula. Cryosphere, 5, 125134, doi:10.5194/tc-5-125-2011.

    • Search Google Scholar
    • Export Citation
  • Scambos, T. A., C. Hulbe, and M. Fahnestock, 2003: Climate-induced ice shelf disintegration in the Antarctic Peninsula. Antarctic Peninsula Climate Variability: Historical and Paleoenvironmental Perspectives, E. Domack et al., Eds., Antarctic Research Series, Vol. 79, Amer. Geophys. Union, 7992.

  • Schodlok, M. P., H. H. Hellmer, G. Rohardt, and E. Fahrbach, 2006: Weddell Sea iceberg drift: Five years of observations. J. Geophys. Res.,111, C06018, doi:10.1029/2004JC002661.

  • Shepherd, A., D. Wingham, T. Payne, and P. Skvarca, 2003: Larsen ice shelf has progressively thinned. Science, 302, 856859.

  • Shepherd, A., D. Wingham, and E. Rignot, 2004: Warm ocean is eroding West Antarctic ice sheet. Geophys. Res. Lett.,31, L23402, doi:10.1029/2004GL021106.

  • Shepherd, A., D. Wingham, D. Wallis, K. Giles, S. Laxon, and A. V. Sundal, 2010: Recent loss of floating ice and the consequent sea level contribution. Geophys. Res. Lett.,37, L13503, doi:10.1029/2010GL042496.

  • Shuman, C., E. Berthier, and T. Scambos, 2011: 2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula. J. Glaciol., 57, 737–754.

    • Search Google Scholar
    • Export Citation
  • Silva, T. A. M., G. R. Bigg, and K. W. Nicholls, 2006: Contribution of giant icebergs to the Southern Ocean freshwater flux. J. Geophys. Res.,111, C03004, doi:10.1029/2004JC002843.

  • Stammerjohn, S. E., D. G. Martinson, R. C. Smith, X. Yuan, and D. Rind, 2008: Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and southern annular mode variability. J. Geophys. Res., 113, C03S90, doi:10.1029/2007JC004269.

    • Search Google Scholar
    • Export Citation
  • Sutherland, W., and Coauthors, 2012: A horizon scan of global conservation issues for 2012. Trends Ecol. Evol.,37, 12–18, doi:10.1016/j.tree.2011.10.011.

  • Tamura, T., K. I. Ohshima, and S. Nihashi, 2008: Mapping of sea ice production for Antarctic coastal polynyas. Geophys. Res. Lett.,35, L07606, doi:10.1029/2007GL032903.

  • Thoma, M., A. Jenkins, D. Holland, and S. Jacobs, 2008: Modelling circumpolar deep water intrusions on the Amundsen Sea continental shelf, Antarctica. Geophys. Res. Lett.,35, L18602, doi:10.1029/2008GL034939.

  • Thompson, D. W. J., and S. Solomon, 2002: Interpretation of recent southern hemisphere climate change. Science, 296, 895899, doi:10.1126/science.1069270.

    • Search Google Scholar
    • Export Citation
  • van den Broeke, M., 2005: Strong surface melting preceded collapse of Antarctic Peninsula ice shelf. Geophys. Res. Lett.,32, L12815, doi:10.1029/2005GL023247.

  • Wilchinsky, A. V., and D. L. Feltham, 2009: Numerical simulation of the Filchner overflow. J. Geophys. Res.,114, C12012, doi:10.1029/2008JC005013.

  • Williams, A., S. Bacon, and S. Cunningham, 2006: Variability of the lower circumpolar deep water in Drake Passage 1926–2004. Geophys. Res. Lett.,33, L03603, doi:10.1029/2005GL024226.

  • Zwally, H. J., D. Yi, R. Kwok, and Y. Zhao, 2008: Icesat measurements of sea ice freeboard and estimates of sea ice thickness in the Weddell Sea. J. Geophys. Res., 113, C02S15, doi:10.1029/2007JC004284.

    • Search Google Scholar
    • Export Citation
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