I'm not going to go over Dr Francis' lecture in detail, or comment much, if you have two hours they'll be well spent watching what she has to say in her own words. Two things I think are worth noting: Dr Francis' interpretation of the Eurasian snowcover impact on boreal cooling is: Increased and earlier Autumn snowcover cools the ground, snow being white reflects sunlight, the cooling this causes drives the temperature gradient south. And as the Jetstream is caused by the temperature gradient between polar air and mid latitude air, this carries the Jet south. Dr Cohen's explanation is more complex, Dr Francis refers to Judah Cohen, on whom I've blogged before, Cohen details interaction by waves between surface where the snow advance occurs and the stratospheric vortex driving the Arctic Oscillation to negative mode. However...
Years ago, when I did my degree (Electronics), one of my lecturers regularly explained that he'd 'lied' the previous term, he needed to give us a less precise picture in order to build up our understanding to nearer the real situation, without leaving us dispirited and daunted by the mathematical subtleties. Likewise, despite the differences, I see Dr Francis' simple explanation as a very reasonable interpretation for those who don't get Cohen's arguments, or like me, just about get what Cohen is talking about.
Anyone following this blog and Neven's Sea Ice Blog will not be surprised by anything in Dr Francis' presentation. However, as she states, the pattern of Arctic impacts on mid latitude weather are starting to form a clear picture, which is fantastic! Am I the only person who finds all this exciting?
Arctic.io has recently started to look at PIOMAS gridded data again, given the quality of the interfaces over there this can only be a good thing. In this post he's produced what I presume is a trial interface using gridded PIOMAS data to produce an interactive map series of thickness for each month of 2012. But it doesn't work in Internet Explorer, I know that he's pursuing a line of programming that works best in Chrome, and this little interface does.
Perhaps of more immediate interest to me was the quotation from Hadley Centre Technical Note 91 - Assessment of Possibility and Impact of Rapid Climate Change in the Arctic, pdf here. That's one I've not read as yet, but the quote posted at Arctic.io fits in nicely with Dr Francis' talk:
Since 2007, the Arctic in the real world has been subjected to anomalous atmospheric forcing with years such as 2007 and 2011 where stronger than normal winds have displaced large volumes of ice (eg, Lindsay et al., 2009) and exposed larger areas of open water which can absorb more heat from the atmosphere. These Arctic circulation anomalies may have been driven in part by El Nino/La Nina (L’Heureux et al., 2008). It is therefore possible that the divergence between PIOMAS and the climate models since 2007 represents internal variability of the climate system. Further research and subsequent years’ observations will confirm whether recent years have been anomalous, or whether they are part of a trend that is underestimated by climate models.Actually, maybe I won't read it, I'm rather bored with people peddling the "internal variability of the climate system" line, it worked a couple of years ago, but not now. We have a new circulation system that just happens to occur after the 2007 crash (ref), which shifted the seasonal cycle of sea ice, a circulation unique to the post 2007 period (ref), and causing and Arctic Dipole which is shown to be linked to sea ice loss episodes (ref). We have a shift of ice from mainly old ice, to a mainly young ice pack (ref), which has important implications for albedo and energy absorption (ref). I really don't think 'weather' is the explanation.
Anyway, back on the subject of Arctic.io, here's three reasons it should be an essential part of your armoury for the 2013 season.
Whole Arctic views.
But to use it you're best using Chrome.