Monday, January 2, 2012
Gulf Stream: Charting the Chaotic Current That Warms Norway
Chaotic: A spaghetti plot shows the trajectories of the drifting buoys. (Credit: Illustration: POLEWARD)
The North Atlantic Current -- popularly known as the Gulf Stream -- warms Norway and Northern Europe. It is the chaos of the seas that warms the country, researchers have discovered. If its waters flowed smoothly north along the Norwegian coastline, the current would deliver far less warmth.
Norway is situated at the same high northern latitude as Greenland, Northern Canada and Northern Siberia, but thanks to the Gulf Stream, its climate is significantly more temperate.
If the Norwegian branch of the North Atlantic Current flowed evenly, it would surge past Norway at a speed approaching one metre per second, roughly as fast as many rivers run. At that rate, the waters would need only 60 days or so to travel the length of Norway's mainland and reach Svalbard. This would mean that less of the current's heat would be transferred to the atmosphere, resulting in a substantially colder climate for Norway.
In the research project POLEWARD: A drifter experiment to quantify the poleward transport, transformation and spreading of oceanic properties, scientists have discovered that the current takes more than 500 days to flow past Norway, giving the waters more time to release their heat and warm up the country. The project received funding from the research programme on Climate Change and Impacts in Norway (NORKLIMA) at the Research Council of Norway.
Using buoys to chart the current
By deploying 150 marine buoys tracked by satellite, the POLEWARD project researchers were able to chart in detail how the current flows northward along the Norwegian coast.
The buoys revealed that the current often travels quickly, but because it is so irregular and thus highly variable -- indeed, chaotic may be the best description -- the Gulf Stream's journey takes perhaps as much as ten times longer than it would if it flowed smoothly. In this way there is time for the warm ocean current to convey a vastly greater proportion of its heat into the atmosphere, from which the warm air is carried on the predominantly westerly winds towards mainland Norway.