Info Does the Gulf Stream warm Europe?

[tursiops]

No, not directly, but it does contribute, indirectly.
The issue is: the GS does NOT get to Europe, but the warmth from it -- transmitted primarily in the overlying atmosphere -- definitely does.

A common myth is that the Gulf Stream (GS) crosses the Atlantic and gets to the British Isles and Europe and keeps them warm.
This is NOT true, not matter how many times you may read it and see pictures like this:

The problem with that picture is it calls the entire ocean circulation across the Atlantic the GS. However, the Gulf Stream is a wind-stress-driven westward intensification that only gets east to the Grand Banks south of Newfoundland, and then peters out and feeds the Canary current going southeastward, and the North Atlantic Current (or Drift) going northeasterward. It is the latter -- driven by thermohaline processes (i,e, vertical circulation caused by warmer and colder, fresher and saltier water; i.e. NOT driven by westward wind stress).

A slightly better picture is this one:

and an even better picture is this one:

A very good article describing all this (NOT in the popular literature!) is:

https://www.americanscientist.org/article/the-source-of-europes-mild-climate

The Wikipedia article is not bad; see the section on "Properties."

Gulf Stream - Wikipedia

en.wikipedia.org

If you want to read an entire book about it, see:

The Gulf Stream

This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed...

www.ucpress.edu

The article in the Encyclopedia Brittanica says,

"The main portion of the Gulf Stream continues north, veering more to the east and passing close to the Grand Banks, south of Newfoundland, where it breaks up into swirling currents. Some of these eddies flow toward the British Isles and the Norwegian seas and form the North Atlantic Current (or Drift). A larger number flow south and east, either becoming part of westward-flowing countercurrents or joining the Canary Current."​

Here, from Gulf Stream - MeteoSwiss.:

"The Gulf Stream is part of two larger circulation systems in the North Atlantic: the AMOC and the North Atlantic Gyre. The Gulf Stream is largely driven by winds and only to a lesser extent by the density-driven AMOC. The AMOC is the current that is largely responsible for the warm climate in Europe and is often mistakenly equated with the Gulf Stream. The Gulf Stream transports around 90 million cubic metres of water per second (= 90 Sverdrup) eastwards. At around 15 Sverdrup, the AMOC accounts for only a small part of its volume. However, the AMOC turns northwards off Europe, while the continuation of the Gulf Stream, the North Atlantic Current, turns southwards. The AMOC releases a lot of heat into the atmosphere in the colder north and consequently warms (northern) Europe. The North Atlantic Current also transports most of the heat it brings along back to the south."​

I'm sure many of you will read this and say you've looked at Google and seen the first picture above and so it must be true...the GS flows to Europe and keeps it warm.
Sorry.

 

[rjack321]

I fixed it for you... This is really an artificial semantic point, kind of like saying the Mississippi River starts in Minnesota when it could just as easily and logically have started in Montana (what we now call the Missouri River). People name stuff but those names don't change where the heat originated and where it moved to and why.

 

[tursiops]

I fixed it for you... This is really an artificial semantic point, kind of like saying the Mississippi River starts in Minnesota when it could just as easily and logically have started in Montana (what we now call the Missouri River). People name stuff but those names don't change where the heat originated and where it moved to and why.

Yes, there are semantics involved, but also physics. The main point is that it is the atmosphere that warms Europe, not the water. And there is an intermediate process between the Gulf Stream and the water that warms the atmosphere that goes east and warms Europe.

It's like you are telling me that when you suck on your second stage, you are sucking air out of your tank. That ignores the intermediate processes....

 

[rjack321]

Well sure the Coriolis effect is acting on both air and water at the same time. And air doesnt hold squat for heat compared to water. But saying the Gulf Stream splits off here and the AMOC starts there and goes towards Scotland and the relatively warm waters off Ireland are somehow "different" or not originally warmed in the Caribbean is not that helpful - that's just how we humans mentally slice and dice geophysical processes that are part of a continuum.

 

[johndiver999]

So let me get this straight... The extension of the GS current carries a huge amount of heat across the entire Altantic Ocean to europe. BUT the GS does not warm europe, it is the air that does it. This is a very important distinction and NOT semantics.

Of course the heat in the air is all supplied by the warm water, but nevertheless it is completely wrong to consider the concept that the GS warms europe. Is that the subject of this entire thread?

 

[tursiops]

Well sure the Coriolis effect is acting on both air and water at the same time. And air doesnt hold squat for heat compared to water. But saying the Gulf Stream splits off here and the AMOC starts there and goes towards Scotland and the relatively warm waters off Ireland are somehow "different" or not originally warmed in the Caribbean is not that helpful - that's just how we humans mentally slice and dice geophysical processes that are part of a continuum.

It is not as arbitrary as you would like to paint it. The Gulf Stream is wind-stress driven; the AMOC is a thermohaline-driven process. Saying it is the same water is disingenuous, and not really correct. The flow in the Gulf Stream is like 150 Sverdrups (millions of cubic meters per second); the NAC (the part the warms the atmosphere that warms Europe) is maybe 30 Sv.

As the Wikipedia article on the NAC curent says,

"The North Atlantic Current, together with the Gulf Stream, have a long-lived reputation for having a considerable warming influence on European climate. However, the principal cause for differences in winter climate between North America and Europe seems to be winds rather than ocean currents (although the currents do exert influence at very high latitudes by preventing the formation of sea ice)."​

The Wikipedia article on the AMOC is pretty good.

Atlantic meridional overturning circulation - Wikipedia

en.wikipedia.org

The American Scientist article says this:

"Why doesn't the ocean exert a greater influence on North Atlantic climate? According to scientists' best estimates, the ocean and atmosphere move about an equal amount of heat in the deep tropics. But at mid-latitudes, the atmosphere carries several times more heat. Thus, if one considers the region north of, say, 35 degrees North, the atmosphere is much more effective than the ocean in warming winter climates. Also, the winter release of the heat absorbed during the summer is several times greater than the amount of heat that the ocean transports from low to high latitudes in a year. Hence it is the combined effect of atmospheric heat transport and seasonal heat storage and release that keep the winters outside the tropics warmer than they otherwise would be—by several tens of degrees."​

 

[rjack321]

It is not as arbitrary as you would like to paint it. The Gulf Stream is wind-stress driven; the AMOC is a thermohaline-driven process.

The reason the AMOC is flowing north-northeasterly (and not some other direction) is because of the earth's rotation and resulting atmospheric circulation (and partly current Continental land masses), not salinity.

 

[tursiops]

The reason the AMOC is flowing north-northeasterly (and not some other direction) is because of the earth's rotation and resulting atmospheric circulation (and partly current Continental land masses), not salinity.

The salinity is the reason for the thermohaline circulation...the vertical component of the "conveyor belt." Heat is lost in the northern regions, the water gets colder (as it loses heat to the atmosphere), and sinks because of its salinity...it is now heavy.

 

[rjack321]

The salinity is the reason for the thermohaline circulation...the vertical component of the "conveyor belt." Heat is lost in the northern regions, the water gets colder (as it loses heat to the atmosphere), and sinks because of its salinity...it is now heavy.
View attachment 855812

Yes exactly, that water mass flows from the tropics up the eastern seaboard, the name changes to the North American current, as that exact same water loses heat to the atmosphere (near Ireland and northwards) it sinks because the loss of heat driven buoyancy supersedes the previously increased density due to evaporative derived higher salinity. The lost Carribean derived heat keeps places like Scotland's air/atmosphere warm-ish compared to similar continental land masses at the same latitude like Labrador.

Saying that is somehow "not" the Gulf Stream water is inaccurate. It's the same heat, the same water exiting the "Gulf stream" which is now 10s of thousands of km away from the "Gulf" and forming the start of the North Atlantic circulation. It's been renamed in part because calling water off Norway the Gulf Stream is challenging (and for good reason). At the SB 9th grade science level it's the same thing and the original jpg is just mislabeled or you could say not fully labeled - it's not technically inaccurate.

 

[tursiops]

Yes exactly, that water mass flows from the tropics up the eastern seaboard, the name changes to the North American current, as that exact same water loses heat to the atmosphere (near Ireland and northwards) it sinks because the loss of heat driven buoyancy supersedes the previously increased density due to evaporative derived higher salinity. The lost Carribean derived heat keeps places like Scotland's air/atmosphere warm-ish compared to similar continental land masses at the same latitude like Labrador.

Saying that is somehow "not" the Gulf Stream water is inaccurate. It's the same heat, the same water exiting the "Gulf stream" which is now 10s of thousands of km away from the "Gulf" and forming the start of the North Atlantic circulation. It's been renamed in part because calling water off Norway the Gulf Stream is challenging (and for good reason). At the SB 9th grade science level it's the same thing and the original jpg is just mislabeled or you could say not fully labeled - it's not technically inaccurate.

Only a fraction of the water and the heat in the Gulf Stream ends up in the NAC; the rest is in the Canary Current, and circulates in the North Atlantic Gyre back into the tropics.
Here is a gret illustration fro Woods Hole Oceanographic Institution's Oceanus magazine; caption is:

"The Atlantic Meridional Overturning Circulation (AMOC) propels warm surface water from the equator to high-latitude regions. There, the water encounters strong winds and cold air temperatures, which causes it to become colder and denser. This cold, dense water sinks into the deep ocean and then is conveyed back southward at depth, creating a conveyor belt-like loop. (Illustration by Eric S. Taylor, © Woods Hole Oceanographic Institution)"​

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