H/T to Paul Vaughan for pointing to a series of comments by Bill Illis on wuwt, which describe and differentiate between the under-ice salt induced sinking which forms Arctic deep water and the Greenland-melt surface waters which flow into the Gulf Stream. These were in response to an alarmist paper which claims that increased freshwater flux could weaken the AMOC and thus global circulation.
Bill Illis responds:
And the salinity in the ocean in the area in question has changed by exactly ZERO. The paper doesn’t address this issue one iota.
The AMOC starts under the sea ice throughout the entire Arctic Ocean basin. Somehow climate scientists have convinced themselves that the deep water formation of the AMOC is next to Greenland. There is no way to correct them because they don’t actually care what the facts are, just what gets them published in the climate theology field.
The sea surface temperatures in the Norwegian Sea range from +2.0C to +10.0C.
The Arctic Bottom Water is -0.5C to -1.0C and is 3000 metres deeper. it has nothing to do with the Nowegian Sea.
The Arctic Bottom Water overflows the canyons and chokepoints out of the Arctic Ocean basin, particularly the Fram Strait canyon, the Denmark Strait and the Greenland-Scotland Ridge.
This map is the best explanation of the AMOC with the dark blues in the Arctic Ocean basin being the sinking part of the AMOC, the Arctic Bottom Water.
This water forms under the sea ice in the Arctic as the water immediately underneath the ice is -1,5C or so (cold and dense) but once its gets an extra flush of salt leaching out of the newly forming sea ice, it now becomes the coldest densest water on the planet and sinks fairly fast actually right to the bottom of the Arctic 4,000 metres down.
This video shows this process in action and it is fascinating.
This water can spend hundreds of years or more at a time in each different basin slowly being pushed out of the Arctic (by the newly forming Arctic Bottom Water coming from above) until it gets to the one of the chokepoints.
And then it literally overflows these chokepoints and falls to the bottom of the Atlantic Ocean 5,000 metres deep. The Denmark Strait overflow is actually the biggest waterfall on the planet. It continues flowing out at the very bottom of the Atlantic finding the deepest channels it can find because it is the densest water there is in the northern hemisphere. It continues flowing south until about 20S where it runs into the Antarctic Bottom Water which is slightly more dense and it flows over top of it (to somewhere else)
THIS is the start of the AMOC. The ice on Greenland plays no part whatsoever except that helps keep the Arctic cold through sunlight it reflects.
The cold (somewhat fresher lets say) water coming off of Greenland on its eastern side, actually becomes part of the greater Labrador Current. It is strictly a surface ocean current and has nothing to do with the AMOC. It is still 33.5 psu salinity which is really not much different than the rest of the world’s ocean but it is still far off the salinity of the AMOC sinking water.
It literally flows all the way around Greenland even going north on its western side and then does a u-turn to flow down the eastern side of Labrador and Newfoundland (usually in the other order but not in this case).
It then hits the Gulf Stream just south of Newfoundland but still on top of the continental shelf here (signifying it is not part of the AMOC – the AMOC is now 5,000 metres deep in the deepest part of the Atlantic nearby).
The Gulf Stream rapidly warms this water back up and it actually becomes part of the Gulf Stream itself (although some still flows down the eastern seaboard for a little while before it also warms up).
This is exactly where the water coming off of the eastern side of Greenland ends up and re-enters the Gulf Stream.
One can go to the Global Hycom ocean model from the US Navy (ie the biggest world experts on the ocean that there are) and see what this current has been doing for the past 30 days or 365 days.
Open “The Last 30 days (gif)” in the SST section to see the whole area in (real – not climate science) action. (it would probably load too slow to link directly on the page).
It is all a “Surface” current and it literally joins up with the warm Gulf Stream.
I should also note that takes this journey very rapidly. It probably only takes 90 days to complete the trip from the northern eastern side of Greenland to reach the Gulf Stream.
Whoever heard of a 90 day AMOC?