New PIOMAS Gridded Data: November 2013

New PIOMAS gridded data (effective thickness fields) has been released up to November, hat-tip to Wipneus for letting me know. So I've interrupted my blogging holiday to post on the new data which gives a great view of 2013 from the point of view of PIOMAS.

The regional PIOMAS derived data I have previously released, and which is used throughout this post, has now been updated through to November 2013, it is available in CSV files here. Thickness calculations have not been updated for 2013 because they need concentration which has not been released.

Once again, thanks to Dr Jinlun Zhang and colleagues at the Polar Science Centre for making the gridded PIOMAS data publicly available.

Go on, say something outrageous...

I've been having problems with the Tang et al paper about summer mid latitude impacts of sea ice loss. Basically I've been so focused on sea ice that I've a stack of papers I need to re-read on atmospheric impacts, and every time I've tried to 'put pen to paper' regarding Tang et al I find myself needing to re-read several other papers. Unfortunately I've already started to wind down for a Christmas break from work and blogging, so I find that I haven't the motivation.

So I've decided that the final post of 2013 will be a look at percentage open water formation, and a clarification of what I think is a tipping point revealed by the PIOMAS data. Regular readers may already have grasped what I've been getting at before, but now is the time to stop hinting (i.e. 'non-linear') and say exactly what I mean.

EDIT 23/7/14 - after months of consideration and 2014 April data, I have concluded that the effect outlined here will be countered by winter ice growth. More here.

Improved Grid Box Area Calculation

I will be posting properly in the New Year once I have a reply from Dr Zhang. However after one final post of 2013, to be posted tomorrow, I will not be blogging until 2014. I wanted to provide the massive improvement to my sea ice data so that those who want to can use the data.

Grid box areas for each grid box in the PIOMAS domain have been recalculated following advice from Dr Zhang. The error from the PIOMAS monthly series is shown below.

Click on it to enlarge, but basically I was running with a -0.6% error with respect to PIOMAS monthly data, now the error is considerably less (green plot).

• Previous data: -0.614% average error.
• New data: +0.002% average error.

For those who want to use the data it is now at a stage where further improvements will be less than the difference between the PIOMAS monthly series, and monthly averages derived from the daily series. I have updated all three CSV files linked to in the previous post presenting PIOMAS gridded data broken down into regions as used by Cryosphere Today.

The data can be found here.

Early freeze season volume gain.

I've accidentally deleted this post while deleting a post in progress about the recent Tang paper, having decided to relegate that to a mid monthly miscellanea post. So this is a quick re-write of the post that was deleted.

Regional PIOMAS Volume Data

I've been busy recently getting the code I use to handle the PIOMAS gridded data into a more tidy state, it was getting the situation where I, the author, was having trouble remembering where the heck I'd coded what. As part of this I've finally dealt with the issue of making a matching set of PIOMAS data broken down into the same regions Cryosphere Today uses. I have also improved the grid box area calculation with help from Dr Zhang.

October Status

New PIOMAS data is now out for October, I've no intention of continuing with monthly status posts, but will do so when there's something to say. So here's an October's status blog post, and at the end there's a link to my new sea ice spreadsheet.

The 2013 Sea Ice Rebound (that never was)

There was no sea ice rebound in 2013, what happened was variation due to weather, the process underway in the Arctic has not stopped. But the increased volume of 2013 could still be one of the most useful features of the post 2010 situation. In this post I use PIOMAS data both from the PIOMAS main volume series, and PIOMAS gridded data, also Cryosphere Today Area (CT Area) and NSIDC Extent.

European Precipitation and Sea Ice Loss

James Screen has released a lot of important papers on Arctic sea ice loss and the atmosphere, he's done it again, in "Influence of Arctic sea ice on European summer precipitation.", not paywalled.

I'm particularly excited about this because it goes some way to supporting something I've been going on about for two years now. I should point out at the outset - it is very unlikely that Dr Screen is aware of my persistent blogging on this subject!

Winter warming and sea ice thinning.

Arctic Amplification is the tendency of the Arctic region to warm more than the global average with Global Warming. While it is an effect initially seen in modelling studies it has been recently found to be emerging from natural variability. I have used PIOMAS gridded sea ice thickness data and NCEP/NCAR atmospheric temperature data to examine the connection between sea ice thinning and winter warming.

Mid Monthly Miscellenea: October.

The time has come, the Walrus said, to talk of many things...

Siberian and Greenland geopotential height anomalies

Early last year I wrote a post on Eurasian snow cover, link, I've revisited this as part of my continuing attempt to explain the Greenland centred summer pattern.

Francis/Vavrus and the slower jetstream.

I've previously mentioned the Francis/Vavrus paper linking mid latitude persistent weather to Arctic Amplification, copy here, but haven't properly blogged on it. However I have drawn the paper in as a possible factor in the behaviour of blocking activity in a previous post. But the conclusions drawn there are not central to that post, merely an aside.

I say this because I'm pretty sure that the Francis/Vavrus paper is wrong in doubt. EDIT - amended in light of reading Dr Francis's response in the WP - see comments. 

Echoes from 1981.

I should be cracking on trying to get to grips with the atmosphere, but it's proving as difficult as I'd feared. So I've given up for the moment, dug out my debit card, and hit Amazon. The only thing I've purchased that's germane to this blog is Hansen's Storms of My Grandchildren, in which Hansen refers to a 1981 paper: Climate Impact of Increasing Atmospheric Carbon Dioxide. Scanned PDF here.

2013 Sea Ice Prediction Review

I have previously made two predictions, one early in the season, one late. Both were in terms of CT Area, and as CT Area is now clearly past the minimum the time has come to evaluate my predictions.

Welcome to the Anthropocene!

From RealClimate, a graph from the Marcott study into Holocene temperatures, which goes some way to explaining why sea ice is crashing now in a way it hasn't done since the mid Holocene (which was solar driven as further images and text on that blog post show. I strongly recommend popping over to RealClimate and reading the whole post.

And if we're foolish enough to continue emitting CO2....

Mid Monthly Miscellanea: September

Rather than doing specific Monthly Status posts over the coming winter I'll be resuming the Mid Month Miscellanea posts. So here's September...

PIOMAS Summer 2013

The PIOMAS data for August 2013 has been out for a few days, so I'm a bit later than normal (work + a cold), but it's now time to review the summer and look at prospects for the coming freeze season.

Summer 2013

Rather than do an August status post this close to the minimum, when the take-home message of the 2013 melt season is already clear, I've decided it's best to do a post on the summer melt of 2013. The actual minimum may warrant a further post, if so that will be done.

Prediction Update.

On 6 July I made my final prediction for the CT Area minimum, now at 26 August it's worth seeing how that prediction has done, so far.

Seeking Understanding vs Spouting Empty Rhetoric

There will be talk of this year representing a reversal of fortune for the sea ice, and an imminent recovery, or that conditions now are the same as in decades before the turn of this century. I don't take this seriously. And I use it as a measure of the complete lack of grasp those expressing such views have on the situation in the Arctic.

Hat tip to Neven, link, for directing me to WTFWT and consequently getting my hackles up. The result is probably better than just the series of images I was about to post, which can be found by scrolling down to the underlined heading.

Mid August Status: The fat lady draws breath

Now in mid August the potential for 2013 catching up on 2007 or 2011 is remote in my opinion, so it's worth explaining why I think that as I've been quiet for a while. Damn, just seen that Neven has posted today along similar lines, well as this is written I'll post anyway.

July Status: PIOMAS Volume

PIOMAS Volume is now available from the main series, I use the term 'main series' to differentiate from the gridded data, the main series data are available from here, bottom of that page. 2013 shows a gain in volume over previous years

July Status Part 2: Atmosphere

NCEP/NCAR Reanalysis data for July is now available, so it is possible to assess what the atmospheric state has been in July, and for the summer so far. The atmospheric state in 2013 continues to be remarkable in the context of the other post 2007 years, and this is clearly the proximate cause of the slow melt season seen in 2013.

July Status Part 1: Cryosphere Today Area

The full data for June are now available for Cryosphere Today Area (CT Area). As usual I'm still waiting for NCEP/NCAR reanalysis to produce July average, and as PIOMAS uses NCEP/NCAR data they don't publish their main series on the first of the month. So I'll start by going over CT Area, atmosphere and volume will follow in the next few days.

If HYCOM is correct.

Looking at CT Area anomalies and the US Navy's HYCOM model, link, I suspect that August may see record losses as did 2012. This means my prediction of early this month is already looking unlikely to be correct.

What does CT Area show?

This post is a few days late due to work commitments, basically a comment on my last post, link, has raised the question; what does the Cryosphere Today Area (CT Area) index actually show?

How Fragmented is the Pack?

There's a discussion going on over at the Sea Ice Forum, link, about whether the pack this year is more fragmented than previous years. I'm with Peter Ellis on this, looking at different satellite systems and at certain areas it's possible to reach either a 'for' or 'against', conclusion. Certain features such as the Laptev/North Pole low concentration anomaly are quite exciting, although it remains to be seen what role that feature will play in the coming season.

I'm not posting to launch into a long boring discussion of the pack floe by floe. I think there's a more objective way to cut to the heart of the issue. The data I use are IJIS Sea Ice Extent index, data, and CT Area, data.

June Status Part 3: PIOMAS Volume.

PIOMAS data is now out and shows a similar pattern of a retarded melt season as does the CT Area data. However the volume losses of June still place 2013 firmly in the post 2007 group. All data from PIOMAS, all volume units in 1000km^3.

June Status Part 2b - Atmosphere and Ice.

In my previous post I produced a series of sea level pressure (SLP) plots from NCEP/NCAR reanalysis showing how anomalous the SLP field for 2013 is in the context of the other post 2007 years, link. As stated previously, looking at Cryosphere Today Area (CT Area) on 30 June one has to go back to 2009 for a single year above 30 June 2013, and back to 2004 to find successive preceding years of higher area for that date. Given the loss of volume in 2010*, and that this was followed by a new record in the CT Area data for 2011, 2012 then setting a new record by a substantial margin, the late start to the melt season in spring 2013 is highly anomalous. *Whilst this was an event first noticed in PIOMAS it was a real event in the real world, and not just an event within the PIOMAS model, link.

June Status Part 2a: Atmosphere - SLP fields.

Rather than present these graphics in an animated gif (which can't be paused), or YouTube (which has poor resolution) I thought it best to put them all on one page. Here is a sequence of NCEP/NCAR sea level pressure (SLP) fields, the 2007 to 2012 average and the previous ten years including this year (2013). Source.

June Status Part 1: CT Area.

OK, rant over, it's time to get back to sea-ice.

Now that Cryosphere Today's area data (CT Area) are in for yesterday, it's possible to summarise the status for June. The take-home message I read from the data is that a new record is now very unlikely based on past year's behaviour due to the late start to melt, despite other indicators of pack condition (for example the Laptev to N Pole region, link). Posts on the atmospheric status (key to understanding the late melt) and PIOMAS will follow when PIOMAS and NCEP/NCAR updates come in for the month of June.

The Central Arctic Thinning: Is It Real?

In the US Navy's HYCOM model there is a persistent, worsening and large region of low concentration ice between the Pole and the Laptev Sea, is it real?

June Cliff Watch

In an earlier post I outlined the June Crash, link, or as I'll now call it in line with others, the June Cliff. It's now happening. Below is a graph of CT Area anomalies (differences from the average seasonal cycle). This will be updated regularly throughout June on this page.

2013 joins 2007, 2010, 2011 and 2012 in having a June Cliff. I'm pretty sure that 2013's June Cliff has now ended, it lasted from 6 June to 18 June. My next post on the Arctic sea ice will be the June Status post, when the PIOMAS data is out, this post will not be updated further.

As mentioned in my previous post, and discussed in the earlier post on the June Cliff (Crash) much of this drop in CT Area is not real loss of area but is due to melt ponding on the ice. This does not mean it has no impact on real area because melt ponds lower the albedo of the surface and absorb more sunlight.

While I now doubt we will see a new record this year, I expect a very exciting season. As with the May Status posts, I expect the June Status to take up more than one post.

Data as of 23/6/13.

In the figures below, Daily is the difference between successive days, Difference is the difference between area on that date and on the same date in 2012.

Date  Area    Daily   Difference
01/6 10.656 -0.035 0.716
02/6 10.581 -0.075 0.703
03/6 10.498 -0.084 0.715
04/6 10.382 -0.116 0.601
05/6 10.291 -0.091 0.535
06/6 10.223 -0.068 0.505
07/6 09.976 -0.247 0.314
08/6 09.815 -0.161 0.301
09/6 09.710 -0.105 0.369
10/6 09.714 +0.004 0.639
11/6 09.617 -0.097 0.775

12/6 09.535 -0.081 0.851
13/6 09.452 -0.083 0.898
14/6 09.384 -0.068 0.974
15/6 09.191 -0.193 0.987
16/6 08.992 -0.199 0.962
17/6 08.865 -0.127 0.918
18/6 08.722 -0.143 0.933
19/6 08.595 -0.127 0.749
20/6 08.597 +0.002 0.826
21/6 08.389 -0.208 0.651
22/6 08.403 +0.014 0.816
23/6 08.272 -0.131 0.768

Source data from Cryosphere Today, link.

May 2013 Status: Part 3, New Gridded PIOMAS Data.

Gridded PIOMAS thickness data has just been released for April and May, hat-tip to Wipneus for announcing it, and as always to the PIOMAS team for doing the extra work of releasing this data pro-bono. The US Navy's HYCOM system is good for day-to-day work, but with monthly data going back until 1978 and a numerical data source, nothing beats PIOMAS as a proxy for Arctic sea ice volume.

May 2013 Status: Part 2, Prospects for the 2013 Minimum.

PIOMAS Main Series data is now out, I use that term to differentiate from the gridded dataset I also use on this blog. In view of this (as you'll see) and the Cryosphere Today (CT) Area index I can't help but wonder if this year will not even match 2012's record, let alone give a new record. As Neven has recently noted this year has been a slow start, link. Is it going to be delayed enough to scupper any chance of a new record in CT Area minimum this year?

The Sine Qua Non of FUBAR.

In my previous post I presented a blink comparison of image R04C04 from the MODIS Arctic Mosaic, link. Hovering the mouse brings up the image ID, which is right of centre, and clicking on the image gives a larger image. Image R04C04 is in the region of low concentration shown in the US Navy's HYCOM model as a result of the recent May storm.

I've used the highest resolution, 250m per pixcel, and stacked a series of images in an image editor, then used crop to select a single region to show ice conditions since 2009 over the exact same region of the pack for the same day of the year (with dither to avoid cloud white-outs), and the 2013 state before the May Storm. I have then turned each image into a negative in order to bring out the water between ice floes, even under cloud. No other manipulation has been done, all images are in original resolution. The ice shows up dark, water between floes as white striations.

The animated gif is available in my Google Docs account, this link should bring up the viewer, which is excellent for large images. The image is too large to post on the blog itself. LINK.

May 2013 Status part 1: The May Storm

May's status blog post will be in two parts. This first part will deal with the May Storm which has had such a striking impact on the ice pack to the Siberian side of the Pole.

Seven Days In May

I couldn't resist the title; Seven Days in May is a classic movie that's on my 'to watch' list. In due course I'll have more to say about the storm that's battered the sea ice over the last few days, and may come back for more next week. In particular what the implications may be.

But for now a picture says everything.

Summer Acceleration

I have recently outlined the changes in the Cryosphere Today Area index (CT Area), using anomalies to examine the changes from the long term average seasonal cycle. I've shown the changes in the CT Area anomalies, link, the autumn response to increasing open water in the summer season, link, and the recent June anomaly crashes, link. I have also covered research showing the majority of surface based Arctic Amplification is a response to summer ice loss, link, and that this amplification is probably being understated by the GISS dataset, link. However I have not addressed a substantial issue, that of the summer acceleration loss of area when compared to the loss of winter area.

The CT Area June Crash

Extent is preferred by professional scientists because it is less sensitive to melt ponds impacting concentration in satellite measurements of sea ice. However I stopped using the various extent indices some time ago because I consider that in seeking to avoid such issues extent is losing valuable information.

There is a new feature of the Cryosphere Today Area series (CT Area), a June crash in anomalies, this is an important feature, which I suspect is a useful indicator of conditions that prime the ice pack for record melts.

Mid May Miscellanea - Housekeeping

Just a quick 'housekeeping' post. I've been busy with other Arctic related matters, but have now updated some data.

2013 PIOMAS Volume Minimum Projection

Over at the Sea Ice Forum there's a long running discussion about predicting sea ice volume, link. This has finally prompted me to pull my finger out and do something I've been pondering for a while. Answering the question: What if I apply previous year's thinning profiles to the most recent thickness data from PIOMAS? What I find is no new record, with 2013 beating 2011, but not beating 2012.

Autumn Sea Ice Area

In my previous post I showed the post 2007 changes to the seasonal cycle of the Cryosphere Today sea ice area index (CT Area) in the context of previous decades. A notable part of this is the rapid climb of anomalies in the autumn after the lowest record area minima.

CT Area Anomalies

Cryosphere Today produce a dataset of sea ice area, which I shorthand as CT Area. Calculating the daily average over a long period gives an average sea ice area for each day (baseline average), subtracting these daily anomalies from the actual sea ice area data for each day of a given gives the daily anomaly. These daily anomalies are the differences from the average seasonal cycle. I use the period 1980 to 1999 as the baseline average period.

In this post I present graphs of the daily anomaly series from 1980 to 2012. This is a place holder for reference from future posts.

Click on any of the images to bring up full screen, with a selection menu at the bottom of the screen (this applies to all posts on this blog).

April 2013 Status

PIOMAS daily series data is now available for April, so it's time to include the Cryosphere Today Area and look at the status of the pack. Later in the year I may bring in discussion of what's happening in regions, but I see nothing at present that's important for the progress of the season in the concentration plots or IR satellite images.

On the problems attendant in denying a real and ongoing physical process.

Am I the only one who's not seen this version of Downfall?

 



 

GISS LOTI and NCEP/NCAR Reanalysis.

In my last blog post (link) I outlined a recent paper that reveals some detail about the structure and cause of Arctic warming, in it I touched upon some concerns with reanalysis. It is notable that NCEP/NCAR doesn't tend to be used in studies of the Arctic, newer reanalysis products such as JRA-25 and ERA seem to be preferred by most researchers. However the reasons for this seem to be in details in literature I've not yet read, I'm not aware of any one paper throwing NCEP/NCAR temperature or pressure outputs into doubt in the Arctic. It would seem that whatever issues there are have not been enough to persuade the PIOMAS team not to use NCEP/NCAR.

But there is one issue I'm aware of; a growing mismatch between NCEP/NCAR reanalysis and GISS Land/Ocean Temperature Index (GISS LOTI).

The Causes of Arctic Amplification.

Arctic Amplification is the term used for the enhanced warming of the Arctic when compared to warming rates for the rest of the globe. While the changes in the Arctic are driven by human activities, as discussed previously, human activities have proven little more than a 'prompting' for a region whose dynamics are driven by powerful feedbacks.

The Arctic is warming, but the pattern of warming over the year, and between surface and aloft is complex, what is causing this warming? In 2012 Screen et al published "Local and remote forcing of observed Arctic warming", PDF in which they used a series of reanalysis data sets and the results of experiments in two climate models to examine the causes of Arctic Amplification.

Mid April Miscellanea.

The mid month round up of odd bits that interest me and don't fit elsewhere is here. You won't find the 'A' word anywhere in this one.

NOSEDIVE!

 

PIOMAS: 2013 so far.

Dr Schweiger has been good enough to let me know that thickness fields from PIOMAS gridded data are now available for 2013 up to March. Previously it seems to have been released in January for the previous year. Let's hope they get the chance to update periodically in what I suspect will be an exciting year on the ice.

Long Tail or Fast Crash?

As explained in my last post I've been puzzled by the potential implications of autumn/winter ice growth in response to summer area minimums to cause a cessation* to sea ice volume loss. EDIT - not really a cessation, just a reduction in the trend of loss.

As a result I've been playing around with some toy models based on past behaviour, on the principle that whatever factors are to play a role in what is coming, these factors are already at work. The issue here is not the closeness to observation or the PIOMAS model, but the qualitative form of the output and whether that helps say what will happen in the future.

March 2013 Status

March PIOMAS data is out, so it's time to look at the current state of the pack. I've decided to continue these monthly status posts up to September, normally I don't follow the melt season very closely, but this one seems to me to be an important test of my understanding of the mechanisms behind the most recent phase of sea ice loss.

It's Pin the Tail on the Donkey time.

Neven has published a pole on this years minimum: What will the CT 2013 Arctic SIA minimum be?
CT means Cryosphere Today, and the question at hand is what will the daily minimum be.

Here's a link to the CT Area data. Here's a link to a thread I've written on spreadsheeting this sort of Arctic sea ice data. And if you don't want to build such a spreadsheet yourself then the first line of the top post there gives a link to such a spreadsheet. I'll be updating that at least once a month with the new data, probably more often later in the season if this year's melt season turns out to be as exciting as I anticipate. Feel free to use/modify/whaddeva, as you need - I don't own the data.

Anyway, here's a link to my answer - what I think this year's minimum will be, or at least the range I think it will be in. In a nutshell it's:

I've voted between 1 and 2 M km^2, this is what I see as most likely, if I had a second vote it would be 2.234 to 2 M km^2. But I now rate the probabilities as around 75% and 25% respectively, with a probability distribution peaking between 1.75 and 2, and a slim tail extending down towards 1M km^2.

There's no numerical backup, just a qualitative argument. I just thought it worth recording here so I can keep a check on progress.

No need to click more...

...there is no more. ;)

Eurasian Snow Cover and Atmospheric Impacts

I've been looking again at the new summer atmospheric circulation pattern. In "The Recent Shift in Early Summer Arctic Atmospheric Circulation.", abstract, Overland et al identify the shift as an Arctic Dipole pattern. However as I have shown, and as Overland et al also state, this has wider impacts.

But is there a role for snow cover changes in driving this new pattern, and if so what is it?

Well I'm not going to post on April 1st...

...that could cause all sorts of misunderstandings.

Here's a rather late Monthly Miscellanea post.

What caused the volume loss in 2010: Part 2.

Back in September 2012 I wrote some posts on the 2010 volume loss in PIOMAS, why it was important, and what caused it. I'm now able to add another layer of detail into the explanation of what caused the 2010 volume loss and consider whether it has any reality outside of the PIOMAS model. I'm more confident that the 2010 volume loss was real, not just a blip in a model.

February 2013 Status

PIOMAS Data are now out so it's time for my February Status post. I hadn't intended to do these each month, but in light of the recent fracturing and the imminence of the Spring melt I've decided to keep with it until September at least. The pressures of overtime however mean this one's a bit shallow and bitty.

The Beaufort Break Up of February 2013

Over the last week there has been a large fracturing event in the Beaufort Sea, the aftermath of this event continues to unfold. This is being discussed at Neven's Sea Ice Blog, and at the new Arctic Sea Ice Forum. In this post I summarise my understanding which has been posted on those sites in a piecemeal fashion.

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."

ASCAT, PIOMAS and the DAM

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.

It's February 20th...

...it must be sea ice puzzle time. ;)

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.

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.

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.

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.

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.

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

2010 PIOMAS

2011 DAM

2011 PIOMAS

2012 DAM

2012 PIOMAS

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.

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.

Cumulative Volume and Area: 2012.

I've been delving into the data I have on sea ice to try to a greater understanding of the changes and to be able to explain the changes in the seasonal cycles of area and volume. As part of that I've been playing around with a different way of looking at the sea ice area and volume data, running the year from the day of maximum. My aim had initially been to look at changes to the seasonal cycle without the year on year losses in volume and area, what came out of the process however needed to be dealt with before the changes in the seasonal cycle could be considered.

End of Month Miscellenea.

First there's Dr Jennifer Francis at the Weather & Climate Summit. I was lucky enough to have a day off and stumble upon this last year. This year Dr Francis covers a lot of what was covered before, and proceeds into a narrative of Arctic impacts on the wider atmosphere. Then there's new stuff from Arctic.io.

PIOMAS gridded data - 2012 is here!

The PIOMAS team have now uploaded the 2012 gridded data to their server, here. Which means more data to analyse. The only downside - it involves programming which I'm not much good at and don't enjoy at all.

A Correction from the Brink.

There comes a time in every blogger's life when a correction to a previous post is needed. Now is the time for me. This refers to my previous post.

An Observation from the Brink.

This post is not reliable: See correction.

I've been thinking about the relationship between volume and area, so I plotted a scatter plot of PIOMAS volume at annual minimum and CT area at annual minimum. I can't believe I've not done this before, or if I have that I've forgotten, not having seen the significance.

Northern Hemisphere Blocking.

Over at Neven's Sea Ice Blog, Steve Bloom posted a link to some data on Northern Hemisphere blocking, I've got to work on the data Steve linked to, but haven't really got to the bottom of the matter. This data holds some exciting detail. I've not reached a firm conclusion on this, I need to read some more papers on blocking. But this post summarises where I've got to.