December 21st, 2012 by Joshua S Hill
A new climate diagnostic tool has revealed gale-force winds whipping around the Greenland coast are driving ocean circulation by affecting ocean waters, deep sea currents and sea ice behaviour.
“We now have a more complete understanding of the complexity of the climate system,” says Moore, a professor in the Department of Chemical and Physical Sciences. “This new diagnostic shows us how the shape of coastline can impact winds, and how the winds in turn drive oceanic events.”
Moore used his new diagnostic tool – as covered in the journal Geophysical Review Letters – to examine Cape Farewell on the southernmost tip of Greenland. Cape Farewell is the windiest oceanic site in the world, experiencing gale force winds called ‘tip jets’ for one-sixth of the time during the winter.
Moore was able to separate out the gale force wind observations by wind direction before reanalysing the patterns from 1979 to 2012, confirming previous hypotheses that tip jets are caused by the sudden and steep elevation of Greenland’s coast, forcing winds to go around the land instead of over, therefore cuasing wind acceleration known as the Bernoulli effect.
However detecting the tip jets was not the extent of what the diagnostic tool was capable of providing. Moore also found that the same winds that resulted in such extreme gale force winds also affected the ocean beneath their travels.
The Cape Farewell area is one of the few places on our planet where sinking occurs, according to Moore. Warm water that is brought up via the Gulf Stream is subsequently stripped of its heat by the tip jets and sunk back down, becoming colder and more dense.
“These winds play a vital role in the thermohaline, or large-scale ocean, circulation which is a very important part of the climate system,” says Moore. “The winds are what cause the return flow for the Gulf Stream, and are an example of how the atmosphere drives ocean circulations.”
“We showed these tip jets form in several areas around Greenland, and in all these regions they play a crucial role in oceanic events,” says Moore, referring to the North East polynya, the melting of glacial ice shelves in fjords along the southeast coast of Greenland, and the creation of eddies, or ocean storms, over the Labrador Sea. “The diagnostic allows us to unify many questions relating to the land, the atmosphere and the ocean.”
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