Sunday 24 February 2013

The Beaufort Sea Ice Lead of February 2013

There's a long lead in the sea ice in the Beaufort Sea at present, it's drawing some attention. So is this an unusual occurrence and is it telling us anything about the state of the sea ice?

Publicly available past archives of sea ice from infra-red (IR) satellites covering this region don't seem to be available. But I've recently commented of ASCAT the successor to QuikScat, so this morning I made a final effort to see if the archives of QuikScat are still available somewhere. After an immense amount of pissing around I finally found them, said pissing around reminds me of how Arthur Dent found the planning notice for the demolition of his house.
PROSSER: But Mr. Dent, the plans have been available in the local planning office for the last nine months!
ARTHUR: Yes, well, as soon as I heard, I went straight round to see them. You hadn’t gone out of your way to call attention to them, had you? I mean, like actually telling anybody.
PROSSER: The plans were on display—
ARTHUR: On display? I had to go down to the cellar to find them!
PROSSER: That’s the display department!
ARTHUR: With a flashlight.
PROSSER: The lights had probably gone out.
ARTHUR: So had the stairs.
PROSSER: But you found the notice, didn’t you?
ARTHUR: Yes, I did. It was "on display" in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying, "Beware of the Leopard."

Friday 22 February 2013


I've previously posted about the current state of the ice in January 2013. As I've just reminded myself of the ASCAT system that has replaced QuikScat, I thought I'd reproduce images from PIOMAS gridded data and the drift age model (DAM) together with ASCAT satellite images.

It's February 22...

...and as that's a Friday, so it's time to give the answers and explain myself.

In my previous (rather frivolous) post I posted four images of a certain region and asked which was from 2013. Here are the answers and an explanation of what I'm getting at.

Sunday 17 February 2013

Cryo-Sat 2 and PIOMAS.

I recently posted with a link to Neven's Sea Ice Blog, the title of that post was 'PIOMAS Vindicated!' That post, and its title, was written before I had sight of the Laxon 2013 paper "Cryo-Sat 2 estimates of Arctic sea ice thickness and volume". Having now read that paper my opinion hasn't changed. But in a recent email exchange someone has called into question my claim that PIOMAS is vindicated. So I thought I needed to explain my view.

Friday 15 February 2013

And Now For Something Completely Different.

Asteroid DA-14 is giving us a close pass today, within the Moon's orbit and closer than geosynchronous satellites, more here. And early this morning in the Urals a meteorite exploded, shattering windows and injuring around 300 people. So far it seems no deaths reported and the reports indicate injuries are light - phew! Aside from the injuries, the major concern I have are the cold weather and loads of people with smashed windows.

Wednesday 13 February 2013

PIOMAS Vindicated!

The new paper from the Cryosat II team is being reported across the web. Rather than launch into another one of my long posts, I'll link to Neven who's done the honours here. That thread will be worth following, at least one person commenting there seems to have the actual paper, which I'm trying to get hold of (for free) before I buy it.

Tuesday 12 February 2013

Open Water Formation Efficiency Part 2.

In part one of these two posts I outlined the relationships between the formation of open water and melt season thinning, April thickness and September thickness using data from the PIOMAS model. However I first came across Open Water Formation Efficiency in a paper by Drs Marika Holland, Cecilia Bitz and Bruno Tremblay. There a specific definition is used, and since reading that paper I've wanted to see how the Arctic is progressing in terms of that definition. Also since reading that paper I've been convinced that open water formation efficiency is the link between the volume loss, as shown by PIOMAS, and the loss of summer sea ice area. This conviction is over what is probably rather an obvious point, but it's often the obvious that intrigues me.

Sunday 10 February 2013

PIOMAS Volume-Thickness Breakdowns.

For a while I've been posting about changes of PIOMAS thickness using the volume breakdown per thickness category. I've now uploaded some new data for people to use. This is a breakdown of the volume/thickness into three regions. I hope it will be of use to people trying to understand the PIOMAS volume data.

Thursday 7 February 2013

January 2013 Status.

PIOMAS volume continues to track behind 2011 and 2012 which entered their respective years very close together.

PIOMAS volume anomalies (baseline 1980 to 1999) show the significance of this lag.

The anomalies imply that the gap between this year and the previous two is closing slightly. This could be due to rapid thermodynamic thickening of the first year ice, and as I will show, there is a lot more of that now.

Calculated thickness is the notional thickness calculated by dividing PIOMAS Volume by Cryosphere Today Area, it reflects the above volume anomalies.

And the anomaly of calculated thickness puts the situation in context of the years since 2000.

Cryosphere Today (CT) area anomalies, as expected, show nothing unusual with respect to recent years

They will get interesting come June, when I expect them to crash as in 2012. This has been a feature of recent years, but before I explain why I think the area anomalies will crash I need to outline some more detail, this time from last December.

The Fowler/Maslanik/Tschudi ice age plots derived from the Drift Age Model (DAM) have now been incremented, moving ice age on by one year. 2012 shows increased ice in the oldest category, but overall first year ice dominates. Here are December thickness plots generated from gridded PIOMAS data in comparison with the ice age plots for the last three years.

2010 DAM

2011 DAM

2012 DAM

If you think that the pattern of thicker ice in PIOMAS agrees with the older ice in DAM then this is something I've noticed and it seems to hold going back for years. This is to be expected as older ice is thickened by compression and ridging. However what I really wanted to show in the last two images is that in comparison to previous years the ice is now predominantly first year ice. It is not guaranteed that it will melt out, but it is more likely for such ice to melt out than for older ice to do so. The thinness of the ice is also reflected in the very low volume at present. Thickening will continue until April, with the central pack thickening a bit more through to May. It is in June that the general loss of thickness will really begin, with the greatest seasonal loss of volume in July. However for the ice area newly covered by first year ice there will be an increase of about 1/3 energy gain throughout the season. That's before we get to the energy implications of more open water forming, possibly more early in the season.

I suspect that the June crash in CT anomalies is due to increasing amounts of first year ice experiencing massive expansion of surface melt ponds and rapid recession from the edges. If I am correct then the current ice state has the potential to make this June's CT area crash the biggest yet.

Conditions at present, more so than any previous year, suggest to me that 2013 will be a significant year, which will at least meet 2012's record given weather not conducive to ice melt. With weather conditions conducive to ice melt a new record could be set by a substantial margin.

Data sources:
Cryosphere Today Area.
Fowler/Maslanik/Tschudi Drift Age Model plots.
PIOMAS Volume series.
PIOMAS Gridded Data.

Wednesday 6 February 2013

Open Water Formation Efficiency Part 1.

What is the link between volume and area changes in Arctic sea ice? For some time I've been intrigued by the concept of 'OpenWater Formation Efficiency' (OWFE) and the relationship between sea ice thinning and the consequent increased exposure of open water, with its attendant impacts; summer albedo feedback and autumn heat loss to the atmosphere. In this first post I try to outline the base relationship and data that goes into calculation of OWFE from PIOMAS gridded data, but the OWFE itself will shown be in part two.

All this is new data to me, so any explanations I put forward are tentative and need more examination.