Mid March Miscellanea.

This is a filler post with a couple of items mainly because I'm too whacked to write much due to work pressures.

PIOMAS: Calculated thickness.

This post has been partially re-written as I posted an old version and editing would have made it a mess - I had changed my mind about a main conclusion (it is possible to get figures from calculated thickness that reflect real on the ice thickness) after referring to Schweiger et al and doing some more work on my spreadsheet. The portion that I've ended up editing is between the EDIT statements. I decided to pull the post and re-write as at the time I realised the problem only four people had opened this page. Apologies to those four people.

The calculated thickness is a useful metric, it allows some diagnosis of whether PIOMAS volume changes are due to changes in area or thickness, and changes in its annual cycle reflect changes that PIOMAS volume suggests are significant. But can the calculated thickness metric be used to say anything about real thickness on the ice pack?

PIOMAS: The Porch and the Roof.

I've previously discussed why I think Spring 2010 saw an event as significant as the Arctic sea-ice crash of 2007. As a result of my last post and the ensuing discussion I am more confident that Spring 2010 was a significant event and that this year, as with 2011, we will see further massive volume losses in the coming Spring. However there are some details that need to be addressed in this post before I go on to look at whether calculated thickness from PIOMAS and extent/area has any value.

Cold Winters: From Theory into Practice?

As reported by BBC News this Winter has seen a period of very cold weather over a large swathe of Europe. I didn't blog about this at the time because I was tied up with the issue of methane emissions from the Arctic. However in view of my previous string of posts on cold winters, and the research of Dr Judah Cohen, especially as Dr Cohen's Snow Advance Index didn't predict a cold winter, this recent event needs addressing. Firstly I should stress that this Winter as a whole over Northern Europe hasn't been cold, nor has the continental US, image. Certainly the pattern associated with winters like 2009/10 has not been apparent, which I take as confirmation of Dr Cohen's forecast for this Winter.

There's another reason for this post. Over at Neven's Sea-Ice Blog, Neven said he'd understood the cold event to have been due to easterly winds, he's correct. But that was due to the position of the dominating high pressure system, with Europe on the south of that system winds there were easterly, however from my reading of the event there was also a significant cold outbreak from the Arctic. That being a point Dr Cohen mentioned to me in an email around the time of the event.

What happened in Spring 2010?

There has been an increasing tendency towards loss of volume in Spring, a look at the seasonal changes in sea-ice volume, using PIOMAS for the volume data, shows that the loss of volume in the PIOMAS series is largely accounted for by Spring volume losses. The other event causing loss of sea-ice volume in the PIOMAS series was the 2007 crash in Arctic sea-ice area/extent, the loss of volume in Spring 2010 rivals the loss of 2007.