File:Seasonal Changes in Arctic Sea Ice - Summer, 2009 (3988013764).webm

Arctic Sea Ice Extent is Third Lowest on Record -- Sea ice cover reaches its minimum extent at the end of each summer. This animation shows the summer retreat of sea ice over the Arctic from July 1 through September 12, as recorded by the AMSR-E instrument on NASA's Aqua satellite. Credit: Cyndi Starr and Trent Schindler, NASA Scientific Visualization Studio U.S. satellite measurements show Arctic sea ice extent in 2009 – the area of the Arctic Ocean covered by floating ice – was the third lowest since satellite measurements were first made in 1979. The ice area at minimum was an increase from the past two years, but still well below the average for the past 30 years. Full Story: www.nasa.gov/topics/earth/features/seaicemin09.html#

Sea ice is frozen seawater floating on the surface of the ocean. Some sea ice is semi-permanent, persisting from year to year, and some is seasonal, melting and refreezing from season to season. The sea ice cover reaches its minimum extent at the end of each summer and the remaining ice is called the perennial ice cover. Duing the summer of 2009, the arctic sea ice reached its minimum extent on September 12th. The 2009 minimum extent was the third lowest extent measured since the beginning of the satellite record in 1979. This animation shows the summer retreat of sea ice over the Arctic from 7/1/2009 through 9/12/2009. The sea ice was defined by a 3-day moving average of the AMSR-E 12.5 km sea ice concentration, showing the region where the sea ice concentration was greater than 15%. The false color of the sea ice was derived from the AMSR-E 6.25 km brightness temperature.

Additional formats and resolutions of this product are available here: svs.gsfc.nasa.gov/vis/a000000/a003600/a003631/index.html