Ocean Dynamics

, Volume 60, Issue 3, pp 563–583 | Cite as

Origin and mechanism of Subantarctic Mode Water formation and transformation in the Southern Indian Ocean

  • Ariane Koch-Larrouy
  • Rosemary Morrow
  • Thierry Penduff
  • Mélanie Juza
Article

Abstract

The sources and pathways of mode waters and lower thermocline waters entering the subtropical gyre of the Indian Ocean are examined. A Lagrangian analysis is performed on an eddy-admitting simulation of the Global Ocean performed by the DRAKKAR Group (NEMO/OPA), which captures the main observed features. We trace the subducted mode water’s pathways, identify their formation regions and trace whether their source waters come from the Atlantic, Pacific or Indian sectors of the Southern Ocean. Three main sites for mode waters ventilation in the Indian sector are identified with different circulation pathways and source water masses: (a) just north of Kerguelen, where 4.2 Sv of lighter Subantarctic Mode Waters (SAMW); σ0 ∼ 26.5) are exported—originating in the Atlantic and Agulhas Retroflection regions; (b) SW of Australia, where 6.5 Sv of medium SAMW (σ0 ∼ 26.6) are ventilated—originating in the southern and denser Agulhas Retroflection region; (c) SW of Tasmania and along the South Australian coast, where 3 Sv of denser SAMW (σ0 ∼ 26.75) are ventilated—originating from three sources: Leeuwin Current waters, Tasman Sea (Pacific) waters and Antarctic Surface Waters. In all cases, modelled mode waters were last ventilated in the Indian Ocean just north of the deepest winter-mixed layers. For the waters subducted SW of Australia, the last ventilation site extends even further north. Waters ventilated in the deepest mixed layers north of the Subantarctic Front are then re-ventilated 5 years later southwest of Australia. The model results raise new hypotheses that revisit the classical picture of the SAMW formation and transformation, where a large homogeneous mixed layer is subducted and ‘slides’ equatorward, essentially maintaining the T/S characteristics acquired at the surface. Firstly, the last ventilation of the modelled mode waters is not in the region of the deepest mixed layers, as previously thought, but further north in regions of moderate meso-scale eddy activity. Secondly, the model shows for the first time a significant source region for Indian Ocean mode waters coming from deep winter-mixed layers along the south Australian coast. Finally, this analysis shows how the mode water characteristics are modified after subduction, due to internal eddy mixing. The simulation shows that resolved eddies have a strong impact on the mixed layer properties and that isopycnal eddy mixing also contributes to the generation of more homogeneous mode water characteristics in the interior.

Keywords

Subantarctic mode water Formation Transformation Eddy mixing OGCM ARGO Winter mixed layers Pathways Southern Indian Ocean 

References

  1. Banks HT, Wood RA, Gregory JM, Johns TC, Jones GS (2000) Are observed decadal changes in intermediate water masses a signature of anthropogenic climate change? Geophys Res Lett 27:2961–2964CrossRefGoogle Scholar
  2. Banks H, Wood R, Gregory J (2002) Changes to Indian Ocean Subantarctic Mode Water in a Coupled Climate Model as CO2 Forcing Increases. J Phys Oceanogr 32:2816–2827CrossRefGoogle Scholar
  3. Barnier B, Madec G, Penduff T, Molines J-M, Treguier A-M, Le Sommer J, Beckmann A, Biastoch A, Böning C, Dengg J, Derval C, Durand E, Gulev S, Remy E, Talandier C, Theetten S, Maltrud M, McClean J, De Cuevas B (2006a) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-admitting resolution. Ocean Dynamics 56:543–567. doi:10.1007/s10236-009-0180-y CrossRefGoogle Scholar
  4. Barnier B et al (2006b) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy permitting resolution. Ocean Dynamics 56:543–567. doi:10.1007/s10236-006-0082-1 CrossRefGoogle Scholar
  5. Barnier B, The DRAKKAR Group et al (2007) Eddy-admitting ocean circulation Hindcasts of past decades. CLIVAR Exchanges 12(3):8–10Google Scholar
  6. Blanke B, Delecluse P (1993) Variability of the tropical Atlantic ocean simulated by a general circulation model with two different mixed layer physics. J Phys Oceanogr 23:1363–1388CrossRefGoogle Scholar
  7. Blanke B, Raynaud S (1997) Kinematics of the Pacific Equatorial Undercurrent: a Eulerian and Lagrangian approach from GCM results. J Phys Oceanogr 27:1038–1053CrossRefGoogle Scholar
  8. Blanke B, Arhan M, Madec G, Roche S (1999) Warm water paths in the equatorial Atlantic as diagnosed with a general circulation model. J Phys Oceanogr 29:2753–2768CrossRefGoogle Scholar
  9. Blanke B, Speich S, Madec G, Döös K (2001) A global diagnostic of interocean mass transfers. J Phys Oceanogr 31:1623–1632CrossRefGoogle Scholar
  10. Blanke B, Arhan M, Speich S, Pailler K (2002) Diagnosing and picturing the North Atlantic segment of the global conveyor belt by means of an ocean general circulation model. J Phys Oceanogr 32:1430–1451CrossRefGoogle Scholar
  11. Brodeau L, Barnier B, Treguier AM, Penduff T, Gulev S (2010) An ERA40based atmospheric forcing for global ocean circulation models. Ocean Modelling 31:88–104CrossRefGoogle Scholar
  12. Bye JAT (1983) The general circulation in a dissipative basin with longshore wind stresses. J Phys Oceanogr 13:1553–1563CrossRefGoogle Scholar
  13. Bye JAT (1972) Oceanic circulation south of Australia. In: DE Hayes (ed) Antarctic Research Series, Antarctic Oceanology II: The Australian–New Zealand Sector. Am Geophys Union 19:95–100Google Scholar
  14. Davis RE (2005) Intermediate-depth circulation of the Indian and South Pacific Oceans measured by autonomous floats. J Phys Oceanogr 35:583–707CrossRefGoogle Scholar
  15. De Miranda AP, Barnier B, Dewar WK (1999) Mode waters and subduction rates in a highresolution South Atlantic simulation. J Mar Res 57:213–244CrossRefGoogle Scholar
  16. Dong S, Gille S, Sprintall J, Talley L (2008) Southern Ocean mixed-layer depth from Argo float profiles. J Geophys Res 113:C06013. doi:10.1029/2006JC004051 CrossRefGoogle Scholar
  17. Feng M, Meyer G, Pearce A, Wijffels S (2003) Annual and interannual variations of the Leeuwin current at 32°S”. J Geophys Res 108(11):3355. doi:10.1029/2002JC001763 CrossRefGoogle Scholar
  18. Feng M, Biastoch A, Böning C, Caputi N, Meyers G (2008) Seasonal and interannual variations of upper ocean heat balance off the west coast of Australia. J Geophys Res 113:C12025. doi:10.1029/2008JC004908 CrossRefGoogle Scholar
  19. Fine RA (1993) Circulation of the Antarctique intermediate water in the South Indian Ocean. Deep-Sea Res 40:2021–2042CrossRefGoogle Scholar
  20. Fine RA, Smethie WM, Bullister JL, Rhein M, Min DH, Warner MJ, Poisson A, Weiss RF (2008) Decadal ventilation and mixing of Indian Ocean waters. Deep Sea Res I 55:20–37. doi:10.1016/j.dsr.2007.10.002 CrossRefGoogle Scholar
  21. Gu D, Philander SGH (1997) Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics. Science 275(5301):805–807CrossRefGoogle Scholar
  22. Hanawa K, Talley LD (2001) Ocean circulation and climate. In: Siedler G, Church J (eds) International Geophysics Series. Academic, San Diego, pp 373–386Google Scholar
  23. Herraiz-Borreguero L, Rintoul SR (2010) Subantarctic mode water variability influenced by mesoscale eddies south of Tasmania. J Geophys Res, doi:10.1029/2008JC005146, in press.
  24. Karstensen J, Quadfasel D (2002) Water subducted into the Indian Ocean subtropical gyre. Deep-Sea Res II 49:1441–1457CrossRefGoogle Scholar
  25. Karstensen J, Tomczak M (1998) Age determination of mixed water masses using CFC and oxygen data. J Geophys Res 103:18599–18609CrossRefGoogle Scholar
  26. Koch-Larrouy A, Madec G, Blanke B, Molcard R (2008b) Quantification of the water paths and exchanges in the Indonesian archipelago. Ocean Dynamics doi:10.1007/s10236-008-0155-4
  27. Large WG, Yeager SG (2004) Diurnal to decadal global forcing for ocean and sea-ice models: The data sets and flux climatologies. Technical Report TN-460 + STR, NCAR, 105Google Scholar
  28. Levitus S, Boyer TP, Conkright ME, O’Brien T, Antonov J, Stephens C, Stathoplos L, Johnson D, Gelfeld R (1998) NOAA Atlas NESDIS 18, WORLD OCEAN DATABASE Vol 1: Introduction. US Gov. Printing Office, Washington, DC, p 346Google Scholar
  29. Madec G (2008) NEMO = the OPA9 ocean engine. Note du Pole de Modélisation. Institut Pierre-Simon Laplace, vol.1, 100 pp. http://www.lodyc.jussieu.fr/nemo/
  30. Marsh R, Nurser AJG, Megann AP, New AL (2000) Water mass transformation in the Southern Ocean of a global isopycnal coordinate GCM. J Phys Oceanogr 30:1013–1045CrossRefGoogle Scholar
  31. McCarthy MC, Talley LD (1999) Three-dimensional potential vorticity structure in the Indian Ocean. J Geophys Res 104:13251–13267CrossRefGoogle Scholar
  32. McCartney MS (1977) Subantarctic mode water. In: Angel MV (ed) A voyage of discovery: George Deacon 70th Anniversary Volume (supplement to Deep-Sea Research). Pergamon, Oxford, pp 103–119Google Scholar
  33. McCartney MS (1982) The subtropical recirculation of mode waters. J Mar Res 40:427–464Google Scholar
  34. Metzl N, Tilbrook B, Poisson A (1999) The annual fCO2 cycle and the air–sea CO2 flux in the sub-Antarctic Ocean. Tellus 51B:849–861Google Scholar
  35. Middleton JF, Bye JT (2007) The physical oceanography of Australia’s Southern Shelves: a review. Prog Oceanogr 75(1):1–41CrossRefGoogle Scholar
  36. Morrow R, Valladeau G, Sallée JB (2008) Observed subsurface signature of Southern Ocean decadal sea level rise. Prog Oceanogr 77:351–366CrossRefGoogle Scholar
  37. Morrow R, Birol F, Griffin D, Sudre J (2004a) Divergent pathways of cyclonic and anticyclonic ocean eddies. Geophys Res Lett 31:L24311. doi:10.1029/2004GL020874 CrossRefGoogle Scholar
  38. Morrow RM, Donguy J-R, Chaigneau A, Rintoul SR (2004b) Cold-core anomalies at the Subantarctic Front, south of Tasmania. Deep-Sea Res 51:1417–1440Google Scholar
  39. Orsi AH, Withworth T III, Nowlin WD Jr (1995) On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep Sea Res, Part I 42:641–673CrossRefGoogle Scholar
  40. Paci A, Caniaux G, Gavart M, Giordani H, Lévy M, Prieur L, Reverdin G (2005) A high-resolution simulation of the ocean during the POMME experiment: simulation results and comparison with observations. J Geophys Res 110:C07S09. doi:10.1029/2004JC002712 CrossRefGoogle Scholar
  41. Pearce AF, Griffiths RW (1991) The mesoscale structure of the Leeuwin current: a comparison of laboratory models and satellite imagery. J Geophys Res 96(C9):16,739–16,757CrossRefGoogle Scholar
  42. Penduff T, Juza M, Barnier B (2007a) Assessing the realism of ocean simulations against hydrography and altimetry. CLIVAR Exchanges 12(3):11–12Google Scholar
  43. Penduff T, Le Sommer J, Barnier B, Treguier A-M, Molines J-M, Madec G (2007b) Influence of numerical schemes on current-topography interactions in 1/4° global ocean simulations. Ocean Sci 3:509–524CrossRefGoogle Scholar
  44. Penduff T, Juza M, Brodeau L, Smith GC, Barnier B, Molines J-M, Treguier A-M (2009) Impact of model resolution on sea-level variability characteristics at various space and time scales: insights from four DRAKKAR global simulations and the AVISO altimeter data. Ocean Sci J 6:1513–1549Google Scholar
  45. Phillips HE, Rintoul SR (2000) Eddy variability and energetics from direct current measurements in the Antarctic Circumpolar Current south of Australia. J Phys Oceanogr 30(12):3050–3076. ISSN1520-0485Google Scholar
  46. Poisson A, Metzl N, Brunet C, Schauer B, Bres B, Ruiz-Pino D, Louanchi F (1993) Variability of sources and sinks of CO2 in the Western Indian and Southern Oceans during 1991. J Geophys Res 98:22759–22778CrossRefGoogle Scholar
  47. Rintoul SR, Sokolov S (2001) Baroclinic transport variability of the Antarctic Circumpolar Current south of Australia (WOCE repeat section SR3). J Geophys Res 106:2795–2814CrossRefGoogle Scholar
  48. Rintoul SR, England MH (2002) Ekman transport dominates local air–sea fluxes in driving variability of subantarctic mode water. J Phys Oceanogr 32:1308–1321CrossRefGoogle Scholar
  49. Sabine C, Key RM, Johnson K, Millero FJ, Poisson A, Sarmiento J, Wallace DWR, Winn CD (1999) Anthropogenic CO2 inventory of the Indian Ocean. Global Biogeochem Cycles 13:179–198CrossRefGoogle Scholar
  50. Sabine C et al (2004) The oceanic sink for anthropogenic CO2. Science 305:362CrossRefGoogle Scholar
  51. Sallée JB, Wienders N, Morrow R, Speer K (2006) Formation of Subantarctic mode water in the Southeastern Indian Ocean. Ocean Dynamics 56:525–542CrossRefGoogle Scholar
  52. Sallée JB, Speer K, Morrow R (2008a) Southern Ocean fronts and their variability to climate modes. J Climate 21(12):3020–3039CrossRefGoogle Scholar
  53. Sallée JB, Morrow R, Speer K (2008b) Eddy heat diffusion and Subantarctic Mode Water formation. Geophys Res Lett 35:L05607. doi:10.1029/2007GL032827 CrossRefGoogle Scholar
  54. Sallée JB, Speer K, Morrow R, Lumpkin R (2008c) An estimate of Lagragian eddy statistics and diffusion in the mixed layer of the Southern Ocean. J Marine Res 66(4):441–463CrossRefGoogle Scholar
  55. Sallée JB, Speer K, Rintoul SR, Wijffels SE (2010) Southern Ocean thermocline ventilation. J Phys Ocean, in pressGoogle Scholar
  56. Sarmiento JL, Gruber N, Brzezinski MA, Dunne JP (2004) High-latitude controls of thermocline nutrients and low latitude biological productivity. Nature 427:56–60CrossRefGoogle Scholar
  57. Sloyan BM, Rintoul SR (2001a) The southern ocean limb of the global deep overturning. Circ J Phys Oceanogr 31:143–173CrossRefGoogle Scholar
  58. Sloyan BM, Rintoul SR (2001b) Circulation, renewal, and modification of Antarctic Mode and Intermediate Water. J Phys Oceanogr 31:1005–1030CrossRefGoogle Scholar
  59. Speer KG (1997) A note on average cross-isopycnal mixing in the North Atlantic Ocean. Deep-Sea Res 44:1981–1990CrossRefGoogle Scholar
  60. Steele M, Morley R, Ermold W (2001a) PHC: a global ocean hydrography with a high quality Arctic Ocean. J Climate 14:2079–2087CrossRefGoogle Scholar
  61. Steele M, Morfley R, Ermold W (2001b) PHC: a global ocean hydrography with a high-quality Arctic Ocean. J Climate 14:2079–2087CrossRefGoogle Scholar
  62. Sverdrup HU (1942) Oceanography for meteorologists. Prentice Hall, New York, 246Google Scholar
  63. Talley LD (1999) Some aspects of ocean heat transport by the shallow, intermediate and deep overturning circulations. In: Clark, Webb and Keigwin (eds) Mechanisms of Global Climate Change at Millennial Time Scales. Geophys Mono Ser, 112. American Geophysical Union, Washington, DC., pp. 1–22Google Scholar
  64. Thompson RORY, Edwards RJ (1981) Mixing and water-mass formation in the Australian Subantarctic. J Phys Oceanogr 11:1399–1406CrossRefGoogle Scholar
  65. Toole JM, Warren BA (1993) A hydrographic section across the subtropical South Indian Ocean. Deep-Sea Res 40:1973–2019CrossRefGoogle Scholar
  66. Vries P de, Döös K (2001) Calculating Lagrangian trajectories using time-dependent velocity fields. J Atmos Oceanic Technology 18(6):1092–1101.<http://doos.misu.su.se/pap/jaot2001.pdf>Google Scholar
  67. Waite AM, Pesant S, Thompson PA, Paterson H, Muhling B, Strezelecki J, Beckley L, Holl CM, Feng M, Griffin D, Gaughan D, Pender L (2007) The Leeuwin current and its eddies: an introductory overview. Deep-Sea Res II 54:789–796CrossRefGoogle Scholar
  68. Wolff J-O, Maier-Reimer E, Olbers DJ (1991) Wind-driven flow over topography in a zonal β-plane channel: A quasi-geostrophic model of the Antarctic Circumpolar Current. J Phys Oceanogr 21:236–264CrossRefGoogle Scholar
  69. Wong APS (2005) Subantarctic mode water and Antarctic intermediate water in the south Indian Ocean based on profiling float data 2000–2004. J Mar Res 63:789–812CrossRefGoogle Scholar
  70. Wong APS, Bindoff NL, Church J (1999) Large-scale freshening of intermediate waters in the Pacific and Indian Oceans. Nature 400:440–443CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Ariane Koch-Larrouy
    • 1
  • Rosemary Morrow
    • 1
  • Thierry Penduff
    • 2
    • 3
  • Mélanie Juza
    • 2
  1. 1.LEGOSToulouse Cedex 09France
  2. 2.Laboratoire des Ecoulements Géophysiques et IndustrielsGrenoble Cedex 9France
  3. 3.Department of OceanographyFlorida State UniversityTallahasseeUSA

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