Monday 3 June 2013

The Sine Qua Non of FUBAR.

In my previous post I presented a blink comparison of image R04C04 from the MODIS Arctic Mosaic, link. Hovering the mouse brings up the image ID, which is right of centre, and clicking on the image gives a larger image. Image R04C04 is in the region of low concentration shown in the US Navy's HYCOM model as a result of the recent May storm.

I've used the highest resolution, 250m per pixcel, and stacked a series of images in an image editor, then used crop to select a single region to show ice conditions since 2009 over the exact same region of the pack for the same day of the year (with dither to avoid cloud white-outs), and the 2013 state before the May Storm. I have then turned each image into a negative in order to bring out the water between ice floes, even under cloud. No other manipulation has been done, all images are in original resolution. The ice shows up dark, water between floes as white striations.

The animated gif is available in my Google Docs account, this link should bring up the viewer, which is excellent for large images. The image is too large to post on the blog itself. LINK.


Kevin O'Neill said...

An interesting contrast. The effects of these cyclones has been known to arctic scientists for years, though I'm only realizing it now.

In A numerical study of ice-drift divergence by cyclonic
wind with a Lagrangian ice model
Kawaguchi and Midsudera conclude, "The ice divergence leads to enhanced heat absorption and ice
melting in the resultant openwater in summer, which strengthens
the surface stratification and reduces ice concentrations. These
processes promote ice divergence further and therefore generate
broader open water areas as studied in this paper. In addition, the
upward heat flux from the open water fraction makes the atmosphere
unstable and θa tends to be smaller (e.g. Thorndike and
Colony, 1982; Lepp¨aranta, 2005), also accerelating the ice divergence.
These interactions among atmosphere–ice–ocean are
likely to give rise to positive feedback effects for the decay of
ice, and should contribute to the summer regression of the Arctic
ice associated with persistent low pressure systems (e.g. Serreze
et al., 2003)."

Chris Reynolds said...

Thanks Kevin,

That pretty much sum up what I've read described (or hinted at) elsewhere.