What’s up with that huge almost-perfectly circular snow-free area?
As far as I can make out, it is centered somewhere near the town of Tyumen.
Is it real or an artifact? I would have thought that missing data would show up in square or rectangular areas, not circles. Did someone set off a big bomb? Leave the oven on? Go really overboard on road salt?
It all depends on how the data is processed and combined. My WAG is, the circle corresponds to the coverage area from the satellite at the instant when there was data corruption.
I remember a few years ago a similar “hole” in satellite data, over the north pole, being used to justify some crackpot “hollow earth” conspiracy theory.
To my mind, the hole in the snow looked sort of octagonal.
And if you look at the (now updated) images in my OP, you can see that the hole is still there, only smaller and no longer circular. Odd.
jjimm, I remember seeing those images, but in that case the missing data was around the pole as the satellite orbit didn’t allow coverage above a certain latitude. Whereas this hole was in the middle of an area with perfectly good coverage…
the hole appears to be an artifact of the data set. NOAA data using satellite imagery does not show the circles. There are two different data sets that are used to create the images - snow cover and sea ice. The sea ice imagery comes from from NOAA data. The snow cover maps are not.
My guess, because I cannot find it on the Cryoshpere Today site, is that the CT data are gathered from ground stations and interpolated for the coverage area. When a datum is not available the value is filled in as zero snow cover and the mathematical interpolation creates the holes. The coverage maps from NOAA, which uses satellite and ground data, minimizes the data gaps or uses a different mathematical interpolation to cover the missing data.
