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Potential temperature ( o C, Levitus 1994)

Potential temperature ( o C, Levitus 1994). Surface. Global zonal mean. Salinity (psu, Levitus 1994). Surface. Global zonal mean. Evaporation – precipitation. Density as function of temp, salinity and pressure. ρ–1000 kg m –3. freezing point. max density.

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Potential temperature ( o C, Levitus 1994)

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  1. Potential temperature(oC, Levitus 1994) Surface Global zonal mean

  2. Salinity (psu, Levitus 1994) Surface Global zonal mean

  3. Evaporation – precipitation

  4. Density as function of temp, salinity and pressure ρ–1000 kg m–3 freezing point max density

  5. Potential density(-1000 kg m–3, Levitus 1994) Surface Global zonal mean

  6. Mixed layer depth

  7. Seasonal variation of mixed layer depth

  8. World ocean currents Map shows vertically averaged currents around the world oceans

  9. Western boundary currents: Gulf Stream SST satellite image, from U. Miami RSMAS Benjamin Franklin’s map (Richardson, Science1980)

  10. Surface wind (NCEP, m/s) January July

  11. Ekman spiral

  12. Coastal upwelling due to Ekman transport

  13. westerlies trades Observed asymmetry of gyres what one might expect what one observes

  14. Annual mean Ekman pumping (m/year)

  15. Friction in western boundary current

  16. World ocean overturning and heat transportResults from a numerical model (Boccaletti et. al 2005) mass flux (Sv) heat flux (PW) 80S 40S Eq 40N 80N

  17. Atlantic salinity and flow

  18. The Great Conveyor Belt

  19. Ocean heat transport by basin

  20. The present perception of Southern Ocean overturning: it makes the global thermohaline circulation possible Lumpkin and Speer (2007) Speer et al., 2000; Sloyan and Rintoul, 2001ab

  21. Mixing is crucial: A scenario with a surface buoyancy forcing of NADW upwelling is problematic Warm sources have to be deeper than cold ones: The Sandström’s theorem NADW Consumption NADW Formation Mixing Intense THC No THC

  22. Mixing is crucial: Different scenarios for the NADW upwelling a) Pushing by deepwater formation c) Pulling by wind stress & surface waves b) Pulling by deep mixing “[…] understanding the physics related to the spatial and temporal distribution of mixing is one of the most important research frontiers in physical oceanography.” Huang (2004)

  23. A simple model of the thermohaline circulation temperature difference salinity difference •  = flow strength, proportional to density difference ,  adim. constants

  24. Multiple equilibria

  25. Change in surface temperature 30 years after thermohaline shutdown

  26. Tropical Pacific sea-surface temperature

  27. Equatorial temperature cross section

  28. Equatorial currents Surface Meridional cross section Equatorial undercurrent

  29. Driving the undercurrent

  30. Water parcel trajectories

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