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Changes in Arctic Ice : Image of the Day
by NASA -- Image courtesy Claire Parkinson and Nick Digirolamo, NASA G...
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Largely natural ''ups and downs'' in a weather system
centered near Iceland have contributed to regional
variations and an overall decrease in Arctic sea ice
cover over the last twenty years, according to new NASA
research. As this semi-permanent low-pressure system
intensifies and weakens, it affects the amount of air
(generally warm) being brought into the Arctic to the
east of the low and the amount of air (generally cold)
being swept out of the Arctic to the west. These changes
in turn affect the amount of ice cover in the respective
regions, adding to the effects of climate warming. Claire
L. Parkinson of NASA's Goddard Space Flight Center in
Greenbelt, Md., highlights the changes in Arctic sea ice
and their possible connection to the Icelandic low-
pressure system in a paper appearing in the most recent
issue of Polar Geography. Parkinson plotted the extent of
sea ice using satellite passive-microwave data from 1979
through 1999. Data were analyzed from the Nimbus 7
satellite and three satellites of the Defense
Meteorological Satellite Program (DMSP). Results confirm
an overall decline in Arctic ice extent that has been
connected with climate warming, but also show regional
differences that suggest there are other influences. The
''Icelandic Low'' is a key to bringing a greater or
lesser amount of warm air into the Arctic depending on
the intensity of the system, and is part of a larger
weather pattern called the North Atlantic Oscillation
(NAO). NAO is the name for changes in the difference of
air pressure between the semi-permanent low-pressure
system centered near Iceland (the Icelandic Low) and a
semi-permanent high-pressure system centered near the
Azores Islands (better known as the Bermuda-Azores High).
On average, both of these systems are present all year;
however, both are strongest in winter. When both the high
and the low intensify and fluctuate in pressure relative
to one another, they change the circulation of cold and
warm air in the region. When the Icelandic Low is strong,
it forces cold Arctic air southward to the area west of
Iceland and Greenland, setting the stage for increasing
sea ice cover in Baffin Bay, the Labrador Sea, Hudson Bay
and the Gulf of St. Lawrence. At the same time, to the
east, warm air that is swept northward reduces ice
extent. This warmer air contributes to the reduced ice
extents east and north of Greenland, and the reduced
extent of ice in the entire Arctic overall. ''When the
Icelandic Low is weak, it will still bring warm air
northward to the east of Iceland, but not as much as when
the Icelandic Low is strong,'' Parkinson said. For more
information, visit:
www.gsfc.nasa.gov/topstory/20011001icepuzzle.html
Icelandic Weather System Helps Decipher Changes in the
Arctic Ice Puzzle For information about other effects of
the North Atlantic Oscillation, read: ../Features/NAO/
Searching for Atlantic Rhythms: Winter Weather and the
North Atlantic Oscillation
Date Published: 2011-06-26 04:29:03
Identifier: arctic_ice_icelandic_low
Item Size: 76324
Media Type: image
# Topics
What -- Polar
Where -- Labrador Sea
Where -- Hudson Bay
Where -- Gulf of St. Lawrence
What -- Nimbus 7
What -- Defense Meteorological Satellite
What -- DMSP
Where -- Iceland
Where -- Goddard Space Flight Center ...
Where -- Bermuda
Where -- Greenland
Where -- Baffin Bay
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nasa
nasaimageofthedaygallery
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