Whenever I visit Cryosphere Today I have a quick look at the main graph on the front page, sometimes play the 30-day animation, and then I'm off to the next Arctic sea ice graph or map. But since a few weeks I've been wondering about something else on the CT website, the images on the comparison page to be precise.
First of all when you compare current dates with those of previous years, you notice that practically the entire ice mass looks very concentrated compared to other years (as far back as the eighties). This has reinforced the pseudo-skeptic position that the ice in the Arctic Basin is so thick it will withstand most of the summer melting and continue its recovery.
But when I compare the comparison page map with the front page map I notice some differences:
Believe it or not, but there are some things I have already found out for myself. The front page map has a much better resolution and thus shows more detail. Both maps also use a different colour scheme to depict ice concentration. And thirdly, I have read somewhere that both maps use different satellite data. The front page map uses AMSR-E data (like Uni Bremen and JAXA do), the comparison page map uses SSM/I (like Arctic ROOS does).
But does that explain the big difference I seem to be seeing in the depiction of polynyas on the map? Look at the Beaufort Sea and the Laptev Sea, or at Hudson Bay and Nares Strait. Look, I say!
I decided to check out which date of the front page map matches the one on the comparison map better:
These look more in tune, but the difference is more than 3 weeks! Isn't that weird? Especially if you consider the fact that the comparison page map doesn't show concentrations that are less than 30%. This means the comparison page map in principle should have bigger polynyas than the front page map, despite different resolutions, colour bars and satellite data. Or doesn't it?
The comparison map is a smaller picture. Maybe that explains some of it. It is certainly feeding Goddard's sense that we are about to witness the start of the next ice age ... ;)
Posted by: David Gould | June 18, 2010 at 03:36
None of these CT maps seem to be keeping up with the MODIS pictures. Look at the Baffin Sea, for instance. Maybe, just maybe, there's a lot of small ice which is being detected by the AMSR instruments which isn't visible on the true-colour MODIS shots. Or maybe there's some other explanation. In any case, animating the MODIS shots makes it clear that the central ice is very broken and highly mobile (for instance, most of the ice between Franz Josef Land and the pole is broken into big floes which is heading towards Fram Strait at 20-30km per day, and melting as it reaches the edge of open water somewhere around 82N).
Posted by: Nick Barnes | June 18, 2010 at 10:54
(Shorter: who you gonna believe? The radar, or your own lyin' eyes?)
Posted by: Nick Barnes | June 18, 2010 at 11:31
The 2010 data looks more like 2009 data. Looks like they have messed up their data sets. I have sent an email to Cryosphere today for a clarification.
We don't need to give the "We Use Wishful Thinking" crowd, or what I often refer to as the "flat earth society" any more ammunition.
I will post if I get a response.
Posted by: Lord Soth | June 18, 2010 at 12:50
LS, I have also had brief contact with CT. They wrote back that their scripts seem to be working fine, although that doesn't rule out data problems at the original archive locations. They are going to keep an eye on this and double check, which is very friendly as they are probably very busy doing science things.
Posted by: Neven | June 18, 2010 at 20:02
Any progress working out what's wrong with the CT mini-maps? The discrepancy with the main map is completely laughable now, and it's just giving ammunition to WUWT.
Posted by: Peter Ellis | June 28, 2010 at 10:35
Nope. Perhaps we'll hear more about it at the end of the melting season.
Posted by: Neven | June 28, 2010 at 13:41
I think it's not so much giving "ammunition" to Goddard et al., as giving "rope." The point now, IMO, would be to document the, uh, "misguided" comments made, so that the egg will better adhere later on.
Two cents.
Posted by: Kevin McKinney | June 28, 2010 at 14:34