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ROC Meeting 21 st February 2006 - UEA

ROC Meeting 21 st February 2006 - UEA. The Antarctic Circumpolar Productivity Belt ( Ito et al. GRL, 2005). RATIONALE . General Paradigm for Export Production In the Global Ocean. High Latitudes. High Latitudes. Equator. Silicate Dominated. Silicate Dominated. CaCO 3 Dominated.

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ROC Meeting 21 st February 2006 - UEA

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  1. ROC Meeting 21st February 2006 - UEA The Antarctic Circumpolar Productivity Belt (Ito et al. GRL, 2005)

  2. RATIONALE General Paradigm for Export Production In the Global Ocean High Latitudes High Latitudes Equator Silicate Dominated Silicate Dominated CaCO3 Dominated

  3. Observed Circumpolar ProductivityBelt (Surface [CHL] from Seawifs)

  4. Southern Ocean Meridional Circulation Wind Speer et al. , JPO, 2000

  5. Global Ocean Nutrient Distribution SAMW AAIW NADW AABW www.ewoce.org

  6. Southern Ocean Nutrient Distribution

  7. Southern Ocean Vertical Circulation • a) Up • = (ET) Ekman Transport • (Wind Driven) • b) b) = Residual Vertical Circulation = ET – Eddy-Flux W @ 220 m (10-6 m s-1)

  8. Southern Ocean Export Production MolSi m-2 yr-1 45 S MolC m-2 yr-1 W @ 220 m (10-6 m s-1) Export Production @ 220 m

  9. Southern Ocean Export Production Schlitzer DSR II, 2002 (gC m-2 yr-1) Ito et al. GRL, 2005

  10. Decoupling Iron from P and Si Fe*(PO4) = Fe – (RFe:P)PO4 Parekh et al., GBC, 2005 Fe*(Si) = Fe – (RFe:Si)PO4 (RFe:P) = 10-4for small phytoplankton (RFe:P) = 10-3for diatoms

  11. Aeolian Dust Input Dutkiewicz et al. , GBC, 2005 From Mahowald et al., 2003 (mmol Fe m-2 yr-1)

  12. Southern Ocean & Fe* Fe*< 0 Fe limits PP Fe*< 0 Fe*> 0 Macro-Nuts limit PP Fe*> 0 Fe*< 0

  13. Wind Aeolian Dust Aeolian Dust Fe*< 0 Fe limits PP Fe*> 0 Si, P limit PP Diatoms rule VE Non-diatoms rule Ekman Layer ACC Residual Circulation Deep Ocean Upwelling

  14. Wind Aeolian Dust Aeolian Dust Fe*< 0 Fe limits PP Fe*> 0 Si, P limit PP Diatoms rule VE Non-diatoms rule Ekman Layer ACC Export Production Export Production Residual Circulation Deep Ocean Upwelling

  15. SO Dust Input & Global (I) Low Dust Input Dutkiewicz et al. ,GBC, 2005 High Dust Input

  16. SO Dust Input & Global (II) ΔPP (HD –LD) gC m-2 yr-1 Dutkiewicz et al. , GBC, 2005 Confirms Sarmiento et al., Nature, 2004 Role ofSAMW forglobal ocean PP

  17. Open Questions & Directions 1) Vertical Circulation, only driver for ACPB ? 2) If not Ballast Effect , Aggregation, or whatelse ? 3) If Climate Change causes an Ecosystem Shift, Positive or Negative feedback ? NOT THAT SIMPLE !!!! (Other factors might change: wind, dust input)

  18. Ciao 

  19. Southern Ocean Nutrient Distribution

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