Spinning ocean mysteries hold vital clues for science

Vortices have a strong effect on the way the ocean behaves. Picture / AP

A polar vortex of chilly air slipped off the top of the world and froze North America over the winter, and the great storms that have flooded so much of Britain in the past few months were brought by cyclonic storms in the Atlantic Ocean.

Vortices are spinning sections of fluid or gas that retain their shape because of the energy within them.

Water flowing down a plughole and tropical tornadoes act in the same way, on a different scale.

In some circumstances, the icy cloak of the high Arctic included, such structures can be surprisingly stable; they are islands of order that in the Northern Hemisphere spin anticlockwise in the sea of atmospheric disorder around that surrounds them.

Because the landscape of Antarctica is less broken up than the Arctic, its own vortex is more insulated from the warmer air around it, which is why the South Pole is even chillier than the North.

Such areas of stability are much more common than once thought. The Maelstrom off the Norwegian coast and its fellow whirlpools have long been known as storms in the sea, which come and go with the movements of currents and tides.

But science has now shown that the oceans are full of such things on a much grander scale, islands of slowly spinning water that constantly track their way across the globe.

Ten thousand marine vortices are travelling the oceans. Each may be 100km across and more than 800m deep.

Their stately gyration - only a few hundred metres an hour at their edges - insulates them from the world outside and means they can last for months or years.

Their flat masses can be detected from space as they are so distinct from the chaotic seas that surround them.

Some are spin-offs from major disturbances such as the Gulf Stream, but most set out on their own. Whatever ocean they live in, almost all travel due west. Sometimes they trap warmth or cold and - like the recent slippage in the Arctic - move it for thousands of kilometres.

These slow vortices are being incorporated into the often difficult mathematics needed to understand the dynamics of the oceans, which are, like the atmosphere, much lumpier than once thought.

This has practical importance in understanding climate, in fisheries, and in dealing with man's abuse of the seas.

Whales, sharks and container ships take little notice of such obstacles. But plankton, small fish and fragments of garbage can become trapped in them for a lifetime and more.

The notorious raft of plastic that has accumulated in the central Pacific is not as big as often painted but it shows how an island of rotating water can concentrate particles within its realm.

In the same way, much of the oil from the 2010 Gulf of Mexico spill became locked in a block of seawater, which spun off a smaller extension that delivered it in huge quantities to a relatively short length of Louisiana coast; the Florida coast was untouched because the impenetrable vortex walls blocked the way.

Scientists have spotted a remarkable parallel between these oceanic circles and more distant spinning rings - black holes that entrap light itself, its photons unable to escape their energy-filled prison.

The mathematics of such structures is fairly well understood, so those who study the complex circulation of the oceans are turning to astronomers for help.