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Arctic sea ice annual freeze   This animation is comprised of Envisat ASAR mosaics of the Arctic Ocean and highlights the changes in sea ice between June and September 2008. The dark grey colour represents ice-free areas while blue represents areas covered with sea ice.  Parry Channel in the Canadian Arctic Archipelago, as seen by Envisat's ASAR on 25 August 2008, when the direct Northwest Passage was open (right image), and on 22 September 2008 when sea ice is closing the direct Northwest Passage.  Arctic sea ice extent as seen by Envisat’s Advanced Synthetic Aperture Radar (ASAR) sensor during mid-September 2007 and mid-September 2008. The Arctic sea areas covered by ice in September 2008, but ice-free in September 2007, are visible in blue. The Arctic sea areas covered by ice in September 2007, but ice free in September 2008, are visible in dark brown. The Arctic sea covered by ice both in September 2007 and September 2008 are visible in light brown.  NIC Chief Scientist Dr Pablo Clemente-Colón aboard the U.S. Coast Guard icebreaker Healy in the Arctic.  These National Ice Center bi-weekly and weekly Arctic hemispheric sea ice charts capture the 2008 retreat of the ice pack from a 25 February 2008 winter maximum extent to 22 September 2008. Although last year’s summer sea ice minimum extent record was not broken, a record amount of the thickest multiyear sea ice was actually lost this season.
The results were obtained from a detailed analysis of Envisat, RADARSAT SAR and QuikSCAT scatterometer data. Release date: 3 December 2009 |