You must have JavaScript enabled in your web browser settings to view the image animations. All images can be accessed directly via anonymous FTP.

The animations behave most predictably in Internet Explorer and Safari browsers. They are less predictable in Netscape/Mozilla/Firefox browsers, where the pull-down menues occasionally appear to be non-responsive. When this occurs, please be patient and try again, or try another browser.

Use the menus to choose the Image, Sensor, Hemisphere, Year and Month.

Image selections are hemisphere-specific:

• (Both hemispheres) "SWE + extent" renders microwave-derived SWE in color range (greens-browns-blues) with additional snow-covered area for 2 or more weeks of the month in red.
• (Northern hemisphere only) "Extent + frequency" renders any microwave-derived extent in grey with percent frequency of visible-derived snow extent in blues. Values are discrete: months with 4 weeks have values of 0% (no snow), 25% (1 of 4 weeks with snow), 50% (2 of 4 weeks with snow), 75% (3 of 4 weeks with snow) or 100% (4 of 4 weeks with snow), and months with 5 weeks have values of 0% (no snow), 20 (1 of 5 weeks with snow), 40 (2 of 5 weeks with snow), etc.

Available dates are sensor-specific (SMMR data are available for 1978 to 1987, etc).

Speed buttons will change the animation speed.

Auto Step buttons advance the date forward or in reverse to the beginning or end of the selected data.

Single Step buttons move the image ahead or back one image at a time.

Auto Step buttons automatically advance the date forward or in reverse for continuous play.

Stop button stops the animation.

Rock button rocks the animation for 4 frames.

To download the image use your browser's Save function (usually a right-click menu option).

It is possible to select an image that doesn't exist. It could be outside the valid date range or missing for some other reason. See the full data set documentation for more information.

If you need additional help, please contact NSIDC User Services.