<p>Complementary to the points about salinity emphasised by TomO and S Verhoef, one more point to emphasise is the role of deep ocean convection. You may have in mind this picture of water sinking because it gets heavy, which is not quite wrong, but you get a more accurate picture if you see that the water column down to about 3000 meter deep is convectively mixing (mainly in winter) in localised areas of the  Greenland, Iceland, Norwegian and Labrador seas. Convection is what you get when dense water lies above lighter fluid, which is as unstable as an egg on its head. </p>

<p>The consequence of this mixing is twofold. </p>

<p>First it shapes the hydrological structure of the deep ocean and determines its organisation into distinct water masses (e.g.: <a href="http://www.soes.soton.ac.uk/teaching/courses/oa631/plot_20w.jpg" rel="noreferrer">http://www.soes.soton.ac.uk/teaching/courses/oa631/plot_20w.jpg</a> ) </p>

<p>Second it induces a strong cooling of the ocean water masses. </p>

<p>Together these effects control the strength of the meridional overturning cell. </p>

<p>If your are after an advanced and authoritative review on this, see <a href="http://onlinelibrary.wiley.com/doi/10.1002/2015RG000493/full" rel="noreferrer">http://onlinelibrary.wiley.com/doi/10.1002/2015RG000493/full</a>, which is open access. </p>

CC BY-SA 3.0
2017-08-24T12:26:26.017Z
2017-08-24T12:26:26.017Z
Michel Crucifix
<p>It not only is cooled but saltwater sea ice separates fresh water in the ice forming heavier brine that drives the cold water circulation.</p>

CC BY-SA 3.0
2017-08-14T17:20:55.150Z
2017-08-14T17:20:55.150Z
TomO
<p>The thermohaline circulation is what you mean I suppose.</p>

<p>The water cools down while traveling North, causing it to become more dense. Like TomO tells, the water gets saltier due to the loss of salt from the ice mass*. The density of the water will therefore increase, resulting in the sinking of water parcels.</p>

<p>*Salt will be released from the sea-ice due to the difference in freezing point of salty water and fresh water. If the temp rises to just below 0*C fresh water will still be frozen, but (dependent on the salinity) the salty ice will melt due to the lower melting point of salty water. Therefore sea-ice will become fresh after a while, and brine is released into the seawater making it more saline. </p>

CC BY-SA 3.0
2017-08-18T12:01:15.587Z
2017-08-18T12:01:15.587Z
S Verhoef
<p>The thermohaline current in the North Atlantic ocean sinks because it gets cooled, or it gets cooled because of sinking?</p>

CC BY-SA 3.0
2017-08-12T16:02:21.650Z
what thermohaline current? The Gulf Stream?
arkaia
<oceanography><ocean-currents><salinity>
Thermohaline current in North Atlantic
luis blas Cabrera
# Thermohaline current in North Atlantic

(Asked by: username_0 on 2017-08-12)

The thermohaline current in the North Atlantic ocean sinks because it gets cooled, or it gets cooled because of sinking?

**Tags:** oceanography, ocean-currents, salinity

> **Comments:**
> **username_1**: what thermohaline current? The Gulf Stream?  

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## 3 answers

### Answer by username_2 on 2017-08-24. Score: 5

Complementary to the points about salinity emphasised by username_3 and S username_4, one more point to emphasise is the role of deep ocean convection. You may have in mind this picture of water sinking because it gets heavy, which is not quite wrong, but you get a more accurate picture if you see that the water column down to about 3000 meter deep is convectively mixing (mainly in winter) in localised areas of the Greenland, Iceland, Norwegian and Labrador seas. Convection is what you get when dense water lies above lighter fluid, which is as unstable as an egg on its head.

The consequence of this mixing is twofold.

First it shapes the hydrological structure of the deep ocean and determines its organisation into distinct water masses (e.g.: <http://www.soes.soton.ac.uk/teaching/courses/oa631/plot_20w.jpg> )

Second it induces a strong cooling of the ocean water masses.

Together these effects control the strength of the meridional overturning cell.

If your are after an advanced and authoritative review on this, see <http://onlinelibrary.wiley.com/doi/10.1002/2015RG000493/full>, which is open access.


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### Answer by username_3 on 2017-08-14. Score: 1

It not only is cooled but saltwater sea ice separates fresh water in the ice forming heavier brine that drives the cold water circulation.


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### Answer by username_4 on 2017-08-18. Score: 1

The thermohaline circulation is what you mean I suppose.

The water cools down while traveling North, causing it to become more dense. Like username_3 tells, the water gets saltier due to the loss of salt from the ice mass\*. The density of the water will therefore increase, resulting in the sinking of water parcels.

\*Salt will be released from the sea-ice due to the difference in freezing point of salty water and fresh water. If the temp rises to just below 0\*C fresh water will still be frozen, but (dependent on the salinity) the salty ice will melt due to the lower melting point of salty water. Therefore sea-ice will become fresh after a while, and brine is released into the seawater making it more saline.


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