Satelliteimage of the Arctic (2ndSeptember, 2012), from the Suomi NPP satellite.  This is a &ld

Satelliteimage of the Arctic (2ndSeptember, 2012), from the Suomi NPP satellite.  This is a “mosaic”,compiled from 14 orbits of the satellite and multiple imagingchannels, then “stitched” together to blend the edges of eachsatellite pass.Satelliteshave allowed scientists to monitor the decline of Arctic sea icesince 1979.  Arctic sea ice usually reaches its minimum extent inMarch (beginning of spring) and its maximum extent in September(beginning of autumn).  Historically, maximum sea ice extent has beenabout 14 – 16 million square kilometres, and minimum extent about 7million square kilometres.  But these numbers have been much lower inrecent years.Arcticsea ice reached a new lowest minimum on 16thSeptember, 2012 – only two weeks after these images were taken.  Onthat day, sea ice covered only 3.41 million square kilometres.Inthis image, the edges of the ice pack, and some fractured areas, canbe seen fairly well.  Some details are obscured by clouds.  Becauseof this, other satellite sensors are needed, such as those thatobserve the microwaves emitted by the ice surface.  The microwavesradiated by the ice pass through clouds, which means the ice surfacecan be measured all year round, even through the long polar night.Sincethe mid-2000s, low minimum extents in the Arctic have become the newnormal. -- source link

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