Neven's IceBlog - On Persistent Arctic Cyclones
EDIT
One thing we know for sure and that's that there's a lot of first-year ice in the Arctic right now. Let's return to our 4 questions at the top of the blog post, with summarized answers:
1. Is PAC-2013 unprecedented?
No, but its effect on the sea ice might be. Previous PACs had substantially more ice below them to withstand the pulling forces of the cyclone.
2. Is it somehow caused by the progressive loss of Arctic sea ice?
It seems that decreased Arctic sea ice area and volume, combined with a radical decrease in spring and summer snow cover on the Northern Hemisphere, play a role in cyclogenesis (love that word) and cyclonic behaviour.
3. If so, will we see these PACs more often?
Could be, it's too early to tell. We had GAC-2012 last year, and PAC-2013 this year. We'll see what happens next. Or to paraphrase the historic quote by Dr Jennifer Francis: How could we not?
4. What will the effect on the sea ice be, short-term and long-term?
We still have to find out what exactly the short-term effect of PAC-2013 will be. Either the clouds and cold that the cyclone brought in, offset the churning and dispersing of the ice pack, and equalling last year's record smashing melting season is virtually impossible. Or the cyclone pre-conditioned the ice pack by causing many holes to show up from Svalbard to the New Siberian Islands, and heavy ice losses will become visible as soon as the weather switches (or even if the weather doesn't switch, like we saw last year in July). For the long-term: If this cyclonic activity early in the melting season helps conserve the ice, even though it's thinner, AND cyclonic activity increases because of Arctic sea ice and NH snow cover loss, then we have a serious negative feedback that could postpone the occurrence of a sea ice-free Arctic.
If it this isn't the case, we have a slightly better set of conditions compared to anti-cyclonic dominance (high pressure systems with clear skies and Beaufort Gyre), but it doesn't really matter in the longer term as it doesn't help the ice pack recover.
EDIT
http://neven1.typepad.com/blog/2013/06/on-persistent-cyclones.html#more
