tagged w/ Gulf Stream
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UK scientists have detected a huge dome of freshwater that is developing in the western Arctic Ocean.
The bulge is some 8,000 cubic km in size and has risen by about 15cm since 2002.
The team thinks it may be the result of strong winds whipping up a great clockwise current in the northern polar region called the Beaufort Gyre.
This would force the water together, raising sea surface height, the group tells the journal Nature Geoscience.
[snip]
Of interest to future observations is what might happen if the anticyclonic winds, which have been whipping up the bulge, change behaviour.
"What we seen occurring is precisely what the climate models had predicted," said Dr Giles.
"When you have clockwise rotation - the freshwater is stored. If the wind goes the other way - and that has happened in the past - then the freshwater can be pushed to the margins of the Arctic Ocean.
"If the spin-up starts to spin down, the freshwater could be released. It could go to the rest of the Arctic Ocean or even leave the Arctic Ocean."
If the freshwater were to enter the North Atlantic in large volumes, the concern would be that it might disturb the currents that have such a great influence on European weather patterns. These currents draw warm waters up from the tropics, maintaining milder temperatures in winter than would ordinarily be expected at northern European latitudes.
[snip]
The creation of the Beaufort Gyre bulge is not a continuous development throughout the 15-year data-set, and only becomes a dominant feature in the latter half of the study period.
This may indicate a change in the relationship between the wind and the ocean in the Arctic brought about by the recent rapid decline in sea-ice cover, the CPOM team argues in its Nature Geoscience paper.
It is possible that the wind is now imparting momentum to the water in ways that were not possible when the sea-ice was thicker and more extensive.
"The ice is now much freer to move around," said Dr Giles.
"So, as the wind acts on the ice, it's able to pull the water around with it. Depending on how ridged the surface of ice is or how smooth the bottom of the ice is - this will all affect the drag on the water. If you have more leads, this also might provide more vertical ice surfaces for the wind to blow against."
One consequence of less sea-ice in the region is the possibility that winds could now initiate greater mixing of the different layers in the Arctic Ocean.
Scientists are aware that there is a lot of warm water at depth.
At present, this deep water's energy is unable to influence the sea-ice because of a buffer of colder, less dense water lying between it and the floes above.
But if this warm water were made to well up because of wind-driven changes at the surface, it could further accelerate the loss of seasonal ice cover.
(click on the link for the complete article)UK scientists have detected a huge dome of freshwater that is developing in the... more
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Every so often the earth chooses to remind us that we really aren't in control of this planet. Greenland's massive runoff causing desalination of North Atlantic Shutdown of thermohaline circulation.Every so often the earth chooses to remind us that we really aren't in control of... more
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A vast expanse of freshwater in the midst of the Arctic Ocean is set to wreak unpredictable changes on the climate in Europe and North America, new scientific analysis has shown.
The water – comprising meltwater from the ice cap and run off from rivers – is at least twice the volume of Lake Victoria in Africa, and is continuing to grow. At some point huge quantities of this water are likely to flush out of the Arctic Ocean and into the Atlantic, which could have significant impacts on the climate. Scientists say they cannot predict when this will happen though.
"This could have an influence on ocean circulation," said Benjamin Rabe of the Alfred Wengener Institute. "It could have an influence on the Gulf Stream."
At present, the freshwater acts as a "lid", preventing the warmer salty water below from meeting the ice, which would melt if the two mixed, according to Rabe. But while it is currently stable, this situation is likely to change as atmospheric circulation patterns shift, and as greater quantities of meltwater spill into the "lake". There were signs of an atmospheric change in 2009 that could have precipitated such an outflow, but that episode did not last.
Laura de Steur, an oceanographer at the Royal Netherlands Institute for Sea Research, said: "The volume of water discharged into the Arctic Ocean, largely from Canadian and Siberian rivers, is higher than usual due to warmer temperatures in the north causing ice to melt. Sea ice is also melting quickly – another new record low for ocean area covered was recently documented by the National Snow and Ice Data Centre, adding even more freshwater to the relatively calm Arctic Ocean."
She added: "Sea ice that is thinner is more mobile and could exit the Arctic faster. In the worst case, these Arctic outflow surges can significantly change the densities of marine surface waters in the extreme North Atlantic. What happens then is hard to predict."
Such an outflow would probably have a measurable impact on the "conveyor belt" or thermohaline circulation, a system of deep ocean and wind-driven currents, including the Gulf Stream, which carries heat from the tropics, said Rabe. An influx of dense, cold freshwater could slow the conveyor belt. If the effect were marked, it would be felt in the form of a change of weather in Europe and America, he said. Europe could find itself cooling, particularly around the Western edges, as the circulations tend to bring warmer air to the continent.
cont.A vast expanse of freshwater in the midst of the Arctic Ocean is set to wreak... more
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An intense spell of cold weather has disrupted life across northern India, reportedly claiming two dozen lives.
The capital, Delhi, has been badly hit by the cold snap, along with Indian-administered Kashmir, Haryana, Punjab and Uttar Pradesh.
In Leh in Kashmir, temperatures dropped to -23.6C - this winter's lowest - on Sunday, weather officials said.
Delhi, which is experiencing one of its coldest winters in years, has been hit by thick fog which disrupted flights.
Sunday was Delhi's coldest day this winter with temperatures dipping to 7.8C - cold by the standards of the Indian capital.
http://www.bbc.co.uk/news/world-south-asia-12106386?utm_source=twitterfeed&utm_medium=twitter
http://174.133.94.26/content/125964/leh-remains-23-deg-c.
http://ibnlive.in.com/news/north-india-reels-under-severe-cold-wave/139307-3.htmlAn intense spell of cold weather has disrupted life across northern India, reportedly... more
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Satellite images on this interactive map show how the Gulf Stream is currently under threat.Satellite images on this interactive map show how the Gulf Stream is currently under... more
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