potential temperature ( o c, levitus 1994) surface global zonal mean
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Western boundary currents: Gulf Stream
Benjamin Franklin’s map (Richardson,
Science1980)
SST satellite image, from U. Miami
RSMAS
World ocean overturning and heat transport
Results from a numerical model (Boccaletti et. al 2005)
mass flux (Sv)
heat flux (PW)
Eq 40N 80N40S80S
Lumpkin and Speer (2007)
The present perception of Southern Ocean
overturning: it makesthe globalglobal thermohaline circulation
possible
Speer et al., 2000; Sloyan and Rintoul, 2001ab
Warm sources have to be deeper than cold ones:The Sandström’s theorem
Mixing is crucial:A scenario with a surface buoyancy
forcing of NADW upwelling is problematic
NADWNADWFormation Formation
NADWNADWConsumption Consumption
Mixing Mixing
No THCNo THC Intense THCIntense THC
“[…] 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)
Mixing is crucial:Different scenarios for the NADW
upwelling
a) Pushing by deepwater formation
b) Pulling by deep mixing
c) Pulling by wind stress & surface waves
A simple model of the thermohaline circulation
= flow strength, proportional to density difference
, adim. constants
temperature difference
salinity difference