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STABILITY OF THE SOUTHERN OCEAN THERMOHALINE CIRCULATION

STABILITY OF THE SOUTHERN OCEAN THERMOHALINE CIRCULATION. Simon Marsland CSIRO Complex Systems Science Southern Ocean Postdoctoral Fellow CSIRO Marine Research CSS Workshop, Coffs Harbour, 10-12August 2004. STABILITY OF THE SOUTHERN OCEAN “THERMOHALINE CIRCULATION”. Simon Marsland

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STABILITY OF THE SOUTHERN OCEAN THERMOHALINE CIRCULATION

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  1. STABILITY OF THE SOUTHERN OCEAN THERMOHALINE CIRCULATION Simon Marsland CSIRO Complex Systems Science Southern Ocean Postdoctoral Fellow CSIRO Marine Research CSS Workshop, Coffs Harbour, 10-12August 2004

  2. STABILITY OF THE SOUTHERN OCEAN “THERMOHALINE CIRCULATION” Simon Marsland CSIRO Complex Systems Science Southern Ocean Postdoctoral Fellow CSIRO Marine Research CSS Workshop, Coffs Harbour, 10-12August 2004

  3. STABILITY OF THE SOUTHERN OCEAN “THERMOHALINE CIRCULATION” Simon Marsland CSIRO Complex Systems Science Southern Ocean Postdoctoral Fellow CSIRO Marine Research CSS Workshop, Coffs Harbour, 10-12 August 2004

  4. A hemispherocentric view:Where are the Southern Ocean formation sites? Schmidt, 1995

  5. THERMOHALINE CIRCULATION AND GLOBAL WARMING:SHUTDOWN OF DEEP OVERTURNING? IMPLICATIONS: CHANGES TO CIRCULATION PATTERNS CHANGES TO CLIMATE CHANGES TO UPTAKE OF ATMOSPHERIC CO2

  6. A collapse in the ocean overturning circulation would be a first order change in the climate system Hirst and O’Farrell, CSIRO Atmosphere

  7. VARIOUS CLIMATE STATES IN RESPONSE TO SURFACE FORCING GLACIAL CYCLES?

  8. DEEP WATER FORMATION SITES

  9. CENSUS OF GLOBAL OCEAN BELOW ZERO CELSIUS UP TO 25% FROM AUSTRALIAN ANTARCTIC BASIN Q? WHERE IS THE DEEP WATER FORMED Rintoul, Antarctic Res, Ser.,75, 1998

  10. COASTAL POLYNYAS

  11. COASTAL POLYNYAS Massom et al., Annals of Glaciol, 33, 391-398, 2001

  12. Mertz Polynya global ocean/sea ice model • Max Planck Institute Ocean Model • Marsland et al, Ocean Modelling, 5, 91-127, 2003 • horizontal 150x130 curvilinear orthogonal grid • vertical 31 levels, 8 in upper 200 m • timestep 300 seconds • approx. 1 model year per week on 4 cpus (SGI Origin) • 20 year spin-up with OMIP (ECMWF) climatology • 1990-2000 variability run with NCEP-NCAR daily forcing • 1996-99 sensitivity runs with perturbed heat/freshwater forcing

  13. MertzHOPE spatial discretisation

  14. Marsland et al., J. Geophys. Res (Oceans), in press, 2004.

  15. Marsland et al., J. Geophys. Res (Oceans), in press, 2004.

  16. SOUTHERN HEMISPHERE SEA ICE SENSITIVITYTO SURFACE AIR TEMPERATURE AREA (x10^6 km^2) VOLUME (x10^12 m^3)

  17. SOUTHERN HEMISPHERE SEA ICE SENSITIVITYTO PRECIPITATION AREA (x10^6 km^2) VOLUME (x10^12 m^3)

  18. Predicted that both air temperature and precipitation will increase under global warming scenario • Ice decreases with increasing air temperature • Ice increases with increasing precipitation • Partially compensating (Marsland and Wolff, JGR, 2001) • What about the polynya effect?? • Small spatial scales currently unresolved by global models

  19. POLYNYA DENSE WATER FORMATIONSENSITIVITY TO CLIMATE CHANGE • STRONG FORMATION PHASE • WEAK RESPONSE TO TEMPERATURE • NO RESPONSE TO PRECIPITATION • WEAK FORMATION PHASE • STRONG REPONSE TO TEMPERATURE • WEAK RESPONSE TO PRECIPITATION • CONCLUSION: BREAKDOWN IN THERMOHALINE CIRCULATION SEEN IN OCEAN/ICE/ATMOSPHERE GENERAL CIRCULATION MODELS WILL BE AMPLIFIED AS THE MODEL RESOLUTION BECOMES SUFFICIENT TO RESOLVE THE COASTAL POLYNYAS (APPROX 2010) • MANUSCRIPT IN PREPARATION

  20. COMPLEX SYSTEMS? • MEME: BOTTOM WATER SOURCE IS COASTAL POLYNYAS • ASSUME CONTINUOUS SPACE/TIME AND THEN MODEL DISCRETELY • WHAT EMERGES? SHUTDOWN IN THERMOHALINE CIRCULATION • AMPLIFIED UNDER GLOBAL WARMING • WHEN SMALL SPATIAL SCALES CONSIDERED • HUMAN/LANDSCAPE INTERACTION???

  21. To survive they ate in December the remaining dogs. This caused the death of Xavier Mertz. On 1 January 1913 he started to suffer from heavy stomach aches. The following days his situation got worse and on 7 January he died. Now Mawson was all alone. www.70south.com/resources/history/ chapters/chapter17

  22. P.J. O’Rourke, Eat the Rich

  23. Schmidt, 1995

  24. THREE BODY PROBLEM?

  25. WITH THANKS TO: • John Church, Steve Rintoul CSIRO Marine Research • Nathan Bindoff, Guy Williams, Bill Budd, Matt Paget Antarctic Climate and Ecosystems Cooperative Research Centre • Mojib Latif, Helmuth Haak, Johaan Jungclaus Max Planck Institute for Meteorology • Tony Hirst, Siobhan O’Farrell CSIRO Atmospheric Research

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