Originariamente Scritto da
zago remigio
Intanto Golfo di Botnia completamente ghiacciato:
Allegato 201937
Mentre a livello emisferico la situazione è tutt'altro che rosea, se si eccettua appunto l'artico europeo: forti deficit si segnalano infatti nell'artico nordamericano (mar di Labrador, stretto di Davis). Le cause vanno ricercate essenzialmente nella lunga fase negativa della
AO.
Allegato 201939Molto interessante invece quanto scritto nell'ultimo update del NSIDC riguardo la correlazione ghiacci autunnali ->
AO- :
Potential links with mid-latitude weather
While the Arctic has been warm, cold and stormy weather has affected much of the Northeast U.S. and Europe. Last winter also paired an anomalously warm Arctic with cold and snowy weather for the eastern U.S. and northern Europe. Is there a connection?
Warm conditions in the Arctic and cold conditions in northern Europe and the U.S. are linked to the strong negative mode of the
Arctic oscillation. Cold air is denser than warmer air, so it sits closer to the surface. Around the North Pole, this dense cold air causes a circular wind pattern called the
polar vortex , which helps keep cold air trapped near the poles. When sea ice has not formed during autumn and winter, heat from the ocean escapes and warms the atmosphere. This may weaken the polar vortex and allow air to spill out of the Arctic and into mid-latitude regions in some years, bringing potentially cold winter weather to lower latitudes. Some scientists have speculated that more frequent episodes of a negative Arctic Oscillation, and the stormy winters that result, are linked to the loss of sea ice in the Arctic. Dr. James Overland of
NOAA Pacific Marine Environmental Laboratory (PMEL) recently noted a link between low sea ice and a weak polar vortex in 2005, 2008, and the past two winters, all years with very low September sea ice extent. Earlier work by Jennifer Francis of Rutgers University and colleagues also suggested a relationship between autumn sea ice levels and mid-latitude winter conditions. Judah Cohen, at Atmospheric and Environmental Research, Inc., and his colleagues propose another idea—a potential relationship between early snowfall in northern Siberia, a negative phase of the Arctic Oscillation, and more extreme winters elsewhere in the Northern Hemisphere. More research on these ideas may shed light on the connections and have the potential to improve seasonal weather forecasting.
Re: Artico verso l'abisso... eppure lo dicevamo che...
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