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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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Lower cell

Lower Cell

What is it

What makes it

What’s missing


Here it is

Here it is

Deacon, Sverdrup

Wyrtki added wind-driven numbers ~2Sv

Callahan, Mollinelli, Warren

Sverdrup, Johnson & Fleming (1942).


Lower cell

The view from Antarctica

Oxygen

Salinity

Orsi


Global box inverse model lumpkin

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.


Lower cell

P6

A8

SR4

A11

I6

S3

S4 composite

I5P

IR6


Northern southern hemisphere forcing

Northern/Southern hemisphere forcing

?


Atlantic ocean overturning cell

Atlantic Ocean overturning cell


Atlantic ocean overturning cell1

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


Three oceans moc

°S

Three Oceans MOC

Atlantic

Southern Ocean

Indo-Pacific

(Ganachaud 48N

28.1 ref level)

Not same solution as published but similar…


Pac ind overturning

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


Controls on strength

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…


Realistic outflow adjusted fluxes and polynyas

S4 (62ºS)

Heat gain in layer (PW)

Realistic outflow: adjusted fluxes and polynyas

unadjusted ECMWF

adjusted

Coastal Polynyas

Adjusted – unadjusted ECMWF (W/m2)


Bottom water formation in the antarctic boxes

Bottom water formation in the Antarctic boxes

Strong

outflow

Unconstrained solution

Solution consistent with CFC measurements

(Orsi, Smethie & Bullister, 2002)

Weak

outflow


Zonal streamfunction with topo

Zonal Streamfunction with Topo


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3D Streampath

Deep upwelling

Isopycnal upwelling

Convection region


Lower cell what s missing

Lower Cell – what’s missing?

Deep diapycnal flux

Cross – ACC pathways

Entrainment (plumes and ridges)

Bottom water evolution

Control by wind and buoyancy flux


Atlantic cell on s and o2

Atlantic Cell on S and O2


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