Royal Navy subs provide insights for Arctic science

The data was gathered by Royal Navy submarines, such as HMS Victorious (Image: Ministry of Defence)

The National Oceanography Centre in the UK has used data on the Arctic Ocean gathered by Royal Navy submarines to study the effects of a possible future shrinking of the ice cap. This meeting of oceanography and military intelligence has seen declassified data from the 1990s analyzed to gain insights into how diminished ice cover affects turbulence in arctic waters.

One of the concerns presented by climate change models is a steady decrease in summer sea ice in the Arctic. If this occurs, it poses the question how will it affect the composition and circulation of the waters, which can have an impact on the chemistry and biology of the sea. Previous thinking put a lot of emphasis on the role of the ice, regarding it as a seal that protected the waters beneath from wind. The idea was that an ice-free Arctic would be stirred up by the winds and become more turbulent, which can cause effects like the mixing of cold, fresh water layers with warmer, saltier ones and accelerate ice melts.

But the Arctic Ocean isn't a simple sealed basin. There are all sorts of currents, eddies, internal waves, and other factors, so to understand the future of the Arctic, it's necessary to have a better understanding of how it behaves under the ice as well as in ice-free regions.

The problem is that the ice-bound Arctic Ocean is extremely large, and civilian scientists have only very limited access to its depths. That's where the Royal Navy comes in. Since the height of the Cold War, the Arctic Ocean has been the silent dueling ground between Russia and NATO. It's the ideal hiding place for ballistic missile-carrying submarines and for decades the Navy has been studying the waters that surround the North Pole very carefully to aid in its hunt for potential hostiles.

Since 1971, the Royal Navy has been carrying out regular missions in the Arctic to gather data about temperature, currents, density and salinity, but its findings have been marked classified as a matter of course. Recently, the NOC was able to get the Ministry of Defence (MoD) to release data collected by submarines traversing the Arctic in August and September 1996, which provided insights into how under-ice turbulence operated and distributed energy in the water in comparison with open seas.

The study showed that the turbulence was very similar in iced over and open seas. According to the NOC team, this indicates that the ice doesn't act as a simple wind-protecting lid – how the ice covering alters the turbulence works in conjunction with other factors, such as ice-ocean shear, ice formation, and brine rejection. The team concluded that it was more the stratification of the water into different layers near the surface rather than just the ice that had a major effect.

The NOC results were published in the Journal of Geophysical Research Letters

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