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Sea Ice Index

July 1, 2013: The Sea Ice Index team has replaced the
22-year base period with a new 30-year version. Read more.

More About Monthly Images

April 2010 Sea Ice Extent for the Northern Hemisphere
April 2010 Sea Ice Extent for the Southern Hemisphere

Monthly Sea Ice Extent

The monthly extent images show the expanse covered by ice at greater than 15 percent monthly mean concentration for the Arctic and Antarctic. The total extent value is given in the bottom margin. It is derived from passive microwave data. The median line (in pink) shows a typical ice extent for that month, based on data from 1981 through 2010. The area around the North Pole that the satellite does not image is assumed to be covered by ice at more than 15 percent concentration.

See documentation for more details »

April 2010 Sea Ice Extent for the Northern Hemisphere
April 2010 Sea Ice Extent for the Southern Hemisphere

Monthly Sea Ice Concentration

The monthly concentration images show a particular month's ice concentration with each 25 km data cell color-coded in shades of blue to white, where dark blue is zero percent ice (ocean) and white is 100 percent ice. The area around the North Pole that is not imaged by the satellite is left out of the images (dark grey circle).

See documentation for more details »

April 2010 Sea Ice Extent for the Northern Hemisphere
April 2010 Sea Ice Extent for the Southern Hemisphere

Monthly Sea Ice Concentration Anomaly

These images of anomalies in ice concentration show, in percent color-coded in shades of blue (negative anomaly) to red (positive anomaly), how much the ice concentration for a month differs from the mean calculated for that month over the 1981 through 2010 time range. The total anomalous area of sea ice for that month is also shown in the bottom margin of the image. The area around the North Pole that is not imaged by the satellite is left out of the images (white circle).

See documentation for more details »

April 2010 Sea Ice Extent for the Northern Hemisphere
April 2010 Sea Ice Extent for the Southern Hemisphere

Monthly Sea Ice Concentration Trend

These images of trends in sea ice concentration show if the trend in sea ice concentration at a particular grid cell location is positive or negative and give some indication of its magnitude in percent change per decade color-coded in shades of blue (negative trend) to red (positive trend). The area around the North Pole that is not imaged by the satellite is left out of the images (white circle).

See documentation for more details »