Arctic Sea Ice Extent, April 3, 2015, Danish Meteorological Institute

4/3/15, "Arctic Sea Ice Extent," DMI, Danish Meteorological Institute, Ocean and Ice Services, "The Northern Hemisphere Sea Ice coverage" "Ice concentration higher than 30%" 

"Sea ice extent in recent years (in million km2) for the northern hemisphere, as a  function of date."

"Total sea ice extent on the northern hemisphere since 2005. The ice extent values are calculated from the ice type data from the Ocean and Sea Ice, Satellite Application Facility (OSISAF), where areas with ice concentration higher than 30% are classified as ice.

The total area of sea ice is the sum of First Year Ice (FYI), Multi Year Ice (MYI) and the area of ambiguous ice types, from the OSISAF ice type product. However, the total estimated ice area is underestimated due to unclassified coastal regions where mixed land/sea pixels confuse the applied ice type algorithm. The shown sea ice extent values are therefore recommended be used qualitatively in relation to ice extent values from other years shown in the figure. In late 2012 sea ice climatology and anomaly data will be available here." via Steven Goddard


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Ice concentration higher than 15% (above graph show 30% or higher concentration):

4/2/15, "Arctic Sea Ice Extent,"  DMI, Danish Meteorological Institute, Ocean and Ice Services, The Northern Hemisphere Sea Ice coverage 

"Sea ice extent in recent years for the northern hemisphere. The grey shaded area corresponds to the climate mean plus/minus 1 standard deviation."
 
"Northern Hemisphere Sea Ice extent

Total sea ice extent on the northern hemisphere during the past years, including climate mean; plus/minus 1 standard deviation. The ice extent values are calculated from the ice type data from the Ocean and Sea Ice, Satellite Application Facility (OSISAF), where areas with ice concentration higher than 15% are classified as ice.

The total area of sea ice is the sum of First Year Ice (FYI), Multi Year Ice (MYI) and the area of ambiguous ice types, from the OSISAF ice type product. The total sea ice extent can differ slightly from other sea ice extent estimates. Possible differences between this sea ice extent estimate and others are most likely caused by differences in algorithms and definitions. Some time in 2013 sea ice climatology and anomaly data will become available here."

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