Click on the dates to select other images. Clicking on an already selected date enables hover mode. Then the images will switch on mouse movements, but be patient the first time an image loads (or preload them first). Clicking on the image steps to the next date or stops a running animation.
Note that this isn't an equal-area projection. The nominal grid cell size of 25 km · 25 km = 625 kmē is true at 70° N (northern coast of Alaska). Cells near the pole have a size of 664 kmē, the southernmost cells 382 kmē. The images on this page use 4 identical pixels to represent 1 grid cell at default image size.
National Snow and Ice Data Center, derived from
data using the
Images are produced by me, but show just the raw data without any
changes. 2008 data are near real-time data and may not be fully consistent with final
data. Unlike the final data they don't show ice concentration below
15 % and have some missing values. I used the files with
To calculate the extent and area data, I filled in missing 2008 data by temporal linear interpolation (or persistence at the end). The unsensored area around the pole (0.311 million kmē) is always fully included in both extent and area. Other than that, no manipulation of the data has been applied (no obviously spurious coastal ice removed, no smoothing). F13 data for 2008 (not available here) yields values very similar to the F15 data.
The values have slightly changed, because NSIDC corrected an error in the region mask where Lake Vänern and Lake Peipus were coded as ocean. That affected 7 pixels with a total area of 4'000 kmē, which is partly covered by (spurious) ice even in summer.