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Lower Cell

Lower Cell. What is it What makes it What’s missing. Here it is. Deacon, Sverdrup Wyrtki added wind-driven numbers ~2Sv Callahan, Mollinelli, Warren. Sverdrup, Johnson & Fleming (1942). The view from Antarctica. Oxygen. Salinity. Orsi. Global box inverse model (Lumpkin).

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Lower Cell

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  1. Lower Cell What is it What makes it What’s missing

  2. Here it is Deacon, Sverdrup Wyrtki added wind-driven numbers ~2Sv Callahan, Mollinelli, Warren Sverdrup, Johnson & Fleming (1942).

  3. The view from Antarctica Oxygen Salinity Orsi

  4. Global box inverse model (Lumpkin) Trop. Pac. box S.Ocn. (Pac) box S.Atl. box inner Wed. box Ross box S.Ocn. (Atl) box Med. box Arctic/GIN box Outer Wed. box Trop. Pac. box Pac. Subpolar box Pac. Subtropical box overflow box Atl. Subpolar box Amery box Atl. Subtropical box Atl. Eq. box S.Ocn. (Ind) box Ind. box Ocean circulation Observations (WBCs, choke point transports, air-sea fluxes, …) Parameterizations (diapycnal fluxes, eddy transports, …) But are they consistent? An initial approach: various air-sea flux climatologies.

  5. P6 A8 SR4 A11 I6 S3 S4 composite I5P IR6

  6. Northern/Southern hemisphere forcing ?

  7. Atlantic Ocean overturning cell

  8. Atlantic Ocean overturning cell Overflow vs Irm/Lab Overturning across 32ºS: 13.1  1.9 Sv upper -18.9  2.7 Sv NADW 5.6  2.0 Sv AABW Saunders&King (1995): -22 Sv NADW Macdonald (1998): -20 Sv NADW Ganachaud (1999): -23 Sv NADW Sloyan&Rintoul (2001): -18 Sv NADW Northward transport, mode-to-intermediate densities (26.0<n<27.4): 11 ± 2 Sv (ECMWF) to 13±2 Sv (NCEP) [8 ± 2 Sv (SOC unadj.)] Sloyan and Rintoul (2001): 16 Sv. Karstensen and Quadfasel (2003): 14 Sv ventilation

  9. °S Three Oceans MOC Atlantic Southern Ocean Indo-Pacific (Ganachaud 48N 28.1 ref level) Not same solution as published but similar…

  10. DEEP OVERTURNING Indian: 9.0  2.8 Sv Toole&Warren (1993): 25 Sv Robbins&Toole (1997): 12 Sv Ganachaud (1999): 11 Sv Sloyan&Rintoul (2001): 23 Sv Bryden&Beal (2001): 10 Sv Pacific: 14.2  3.2 Sv Ganachaud (1999): 10 Sv Sloyan&Rintoul (2001): 26 Sv Wijffels et al. (2001): 16-20 Sv Pac, Ind overturning Indian Ocean Pacific-Indonesian Throughflow: 12.42.1 Sv Pacific Ocean

  11. Controls on strength Wind versus buoyancy Atlantic ~ half subpolar gyre convection and half overflow Var of AMOC ~ var of wind Var of overflow ~ weak? Southern Ocean Coastal polynyas Occasional open ocean polynyas Overflow plumes and entrainment Mixing over topography (IWs and sills) Consider coastal polynyas…

  12. S4 (62ºS) Heat gain in layer (PW) Realistic outflow: adjusted fluxes and polynyas unadjusted ECMWF adjusted Coastal Polynyas Adjusted – unadjusted ECMWF (W/m2)

  13. Bottom water formation in the Antarctic boxes Strong outflow Unconstrained solution Solution consistent with CFC measurements (Orsi, Smethie & Bullister, 2002) Weak outflow

  14. Zonal Streamfunction with Topo

  15. 3D Streampath Deep upwelling Isopycnal upwelling Convection region

  16. Lower Cell – what’s missing? Deep diapycnal flux Cross – ACC pathways Entrainment (plumes and ridges) Bottom water evolution Control by wind and buoyancy flux

  17. Atlantic Cell on S and O2

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