Expedition to Svalbard to study the Gulf Stream
A research team from the University of Gothenburg is travelling to Svalbard in August on the research vessel Skagerak to investigate deep water formation in the northernmost part of the Gulf Stream.
“If you are interested in finding out whether the Gulf Stream will collapse or not, then you have to do research here,” says Anna Wåhlin, Professor of Oceanography at the Department of Marine Sciences, University of Gothenburg.
The Gulf Stream can be said to 'turn' at Svalbard. This happens because the warm surface water of the current cools down and the salinity rises, making the water heavier. The heavier water then sinks to the bottom of the ocean and flows back southwards, leaving room for new warm surface water. The redistribution of the different water masses is important for the global ocean circulation to work: In with warmer surface water, out with colder deep water.
“In Svalbard, we want to detect what happens when the water becomes heavy enough to start sinking and forming deep water. We will study salinity, temperature, and oxygen levels and follow the deep water’s route out of the interior of Storfjorden, onto the continental shelf, and back into the North Atlantic. We want a figure on how much deep water is formed, and why so much is formed," says Anna Wåhlin, expedition leader.
Storfjorden important part of the Gulf Stream
Storfjorden in Svalbard is unusual in terms of deep water formation. Here, a lot of sea ice is created when the saltwater freezes, especially in winter, but also to some extent in summer. And when saltwater freezes, ice crystals consisting of fresh water are formed, which means that the salt is expelled and remains in the seawater – which therefore becomes even saltier and subsequently heavier.
“The water is very salty and heavy when it leaves the fjord, and then it mixes with the surrounding water and the salinity drops. If you want to research whether the Gulf Stream will slow down, this process is part of it. It is important because it affects the global ocean circulation," says Anna Wåhlin.
Will the Gulf Stream collapse?
“No, there is nothing to suggest that the Gulf Stream will collapse. The driving forces behind it have not changed, i.e. the wind systems in the North Atlantic and the deep water formation in the north, and the long time series show a stable current system with some variations."
"But we need more knowledge, including this northern part where deep water formation takes place, and we need long time series to make reliable comparisons. Storfjorden is special because there already are long time series of data to compare with, so we can see what has changed," says Anna Wåhlin.
“Couldn't have done it without R/V Skagerak”
The researchers are travelling to Svalbard on the University of Gothenburg's research vessel Skagerak to conduct their research. Under the ice of Storfjorden, the researchers will send in a remotely operated vehicle – ROV – to take measurements, scan small areas, and take photos.
“This is important to better understand the processes inside the ice. We want to get under the ice to see exactly what it looks like when the water leaves the ice. We hope to get really nice photos of the process called "brine rejection”, that is, when the saltwater freezes and the salt is expelled, says Anna Wåhlin.
The researchers will then use the R/V Skagerak to follow the deep water current for ten days and take samples around the clock. They will travel for half an hour, then stop for an hour to take water samples with CTD, and then continue on.
“We have a fantastic ship in the Skagerak that makes this type of research possible with the existing equipment on board. It’s otherwise a lot of work to round up measuring equipment, make sure that everything works, dispatch containers, unpack, and then do everything in reverse after the expedition. And larger ships require that you have sometimes 10 – 12 projects that must compete for ship time. Then each project becomes weakened and there is absolutely no time for detailed process studies like this."
"I wouldn't have been able to do this research without Skagerak," says Anna Wåhlin.
Writer: Annika Wall
