Short to Medium Term Arctic Sea Ice Conditions Discussion

[ChrisReynolds]

Frivolousz,

(This is not directed at you Chris.)

No problem if it is. I was not aware of the paper you linked to. But it seems we agree about HYCOM thickness being an issue of doubt.

I'm not well enough to go digging more but this winter HYCOM thickness has seemed to be pretty much in line with PIOMAS (IIRC). Which as I've noted elsewhere on this board is probably due to thermodynamic thickening to ~2m thick being relatively trivial physics, and the predominance of FYI this year.

Do we agree that ice movement is likely to be less problematic?

[Vergent]

Saying HYCOM is crap shows total ignorance.

Google: "No results found for "HYCOM is crap"."

Straw-man argument.

Vergent

It was in response to frivolousz:

I just don't see how graphs that are so far off from reality really tell us much.  Because of them being such crap.  We can't apply a uniform amount to deduct in terms of thickness. 

I agree that just because there are large differences to total volume, doesn't mean Hycom is cr*p. It almost certainly is pretty good for its intended purpose (risk to shipping). Even if it is biased high from our point of view does not mean it is useless for us let alone cr*p.

Google: "No results found for "HYCOM is crap"."

Straw-man argument.

Vergent

If you are trying to say what I said was straw man.  Well on the other board you broke out some nifty volume numbers on Cryosat and Hycom to show the "other" side how wrong they were.


I hope you are not going back on that now that it shows big melting under some of the ice.

A straw man or straw person, also known in the UK as an Aunt Sally,[1][2] is a type of argument and is an informal fallacy based on misrepresentation of an opponent's position.[3] To "attack a straw man" is to create the illusion of having refuted a proposition by replacing it with a superficially similar yet unequivalent proposition (the "straw man"), and to refute it, without ever having actually refuted the original position.[3][4] This technique has been used throughout history in polemical debate, particularly in arguments about highly charged, emotional issues.

The straw man(men) were "the people who say HYCOM is crap" seawolf, a guest troll was making a personal attack against Friv, but disguising it as a generality. I agree with Friv, it is inconsistent to on the one hand dismiss HYCOM thickness as being over stated, but then getting excited when   it shows thin ice in the CAB. However I would not call HYCOM thickness cr@p, I would call it troll food.

It is unfortunate that they let "guests" post. We were having a rather jolly time naming the Basin Blight(thanks for that Terry)

Speeking of which. The blight is not limited to the Laptev side. Polynyas are opening up elsewhere.



r05c03

[jdallen]

Easy there Vergent - I don't get a sense of Seawolf as a troll.

And yes, r05c03 is looking very interesting.  I've been doing overlays on IJIS/Jaxa, year over year. While cryosphere says we are 350+ from 2012, the visual difference doesn't seem so great.  I agree HYCOM could use some work on thickness volume; I expect they already know that.  I do find the animations useful for understanding trends in the ice.  The seem to do ok qualitatively, if not quantitatively. 

That said, most of our modeling comes down to a SWAG with all the variables bouncing around like they are currently...  Even our direct observations require a certain amount of guesswork in interpretation.

[Nightvid Cole]

(...)

The straw man(men) were "the people who say HYCOM is crap" seawolf, a guest troll was making a personal attack against Friv, but disguising it as a generality. I agree with Friv, it is inconsistent to on the one hand dismiss HYCOM thickness as being over stated, but then getting excited when   it shows thin ice in the CAB. However I would not call HYCOM thickness cr@p, I would call it troll food.

It is unfortunate that they let "guests" post. We were having a rather jolly time naming the Basin Blight(thanks for that Terry)

Well, there needs to be a way for new posters to be able to accumulate enough posts to build status (I assume you aren't referring to unregistered users getting on...)

Maybe we just need a good moderator force. Until then, don't feed the trolls...

Speeking of which. The blight is not limited to the Laptev side. Polynyas are opening up elsewhere.



r05c03

That hole in the ice pack NE of Point Barrow is the biggest of the cracks from Feb/Mar (I've been tracking it on MODIS and ASCAT almost the whole time...)

[Vergent]

Cole,

I am saying he is unregistered. He has no profile. He has only made one(straw man, insulting) post. the by-line says:

seawolf
guest

You can't click on seawolf and get to a profile.

I guess they are letting people sign in with facebook or something.

Verg

[Frivolousz21]

Frivolousz,

(This is not directed at you Chris.)

No problem if it is. I was not aware of the paper you linked to. But it seems we agree about HYCOM thickness being an issue of doubt.

I'm not well enough to go digging more but this winter HYCOM thickness has seemed to be pretty much in line with PIOMAS (IIRC). Which as I've noted elsewhere on this board is probably due to thermodynamic thickening to ~2m thick being relatively trivial physics, and the predominance of FYI this year.

Do we agree that ice movement is likely to be less problematic?

Totally.  I am pretty sure they model the ice movement from below and use the GFS for the surface. 

[jdallen]

Totally.  I am pretty sure they model the ice movement from below and use the GFS for the surface. 

That said, it appears the Fram has been re-activated...

[Frivolousz21]

The Atlantic side has been decimated so far for this time of year.  The models continue a compaction regime on it from the Laptev and at times direct inflow.  It's so screwed. 

[Vergent]

Friv,

Hycom says that area has a uniform 80-100% concentration, Lance-Modis must be imagining things. Respect the model, after all, they worked so hard. Who are you going to believe, HYCOM, or your own eyes?

Verg

[ktonine]

HYCOM shows fairly dramatic changes in both extent and concentration in the Atlantic sector.

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicen_nowcast_anim30d.gif


I'm always amused at the dismissals of HYCOM.  It's a tool built for a specific purpose - and that purpose doesn't include*us* as one of the endusers.  Given its purpose it is going to overstate both thickness and concentration.  Knowing that makes it a useful tool.  Ignoring its purpose amounts to misusing the tool.

It's different but similar to the constant 'it's only a model' complaints we hear regarding PIOMAS.  I get really tired of people complaining about one or the other.  View them, take their limitations into account, and synthesize it with the other information available. 

If you don't want to use it - fine.  But there are plenty of us who look at all the data available - including PIOMAS and HYCOM - and find that it informs our knowledge of the arctic and we'd know less if they suddenly disappeared. 

If you aren't gleaning information from them then perhaps the problem lies more with your understanding and use of them than their known limitations.

<snip>end rant</snip>

[Vergent]

Ktonine,

There is a fundamental difference between models and observations, its the same difference between Sim-city and a live web cam. While models can and should resemble reality, they are not sources of data. When there is a difference between model and observation, the model has a problem. Read this carefully from PIOMAS.

Purpose

.... Comparisons of the model estimates of the ice thickness with observations help test our understanding of the processes represented in the model that are important for sea ice formation and melt.

Bold mine

PIOMAS estimated that March 2012 and March 2013 had identical volumes. CT measured identical areas, but Cryosat2 measured an 8% reduction in thickness. Which of the following is true?

A) The decline in winter sea ice volume continues.

B) The decline in winter sea ice volume stopped.

HYCOM estimates sea ice concentration along the Barents Sea is in the 80-100% range. Looking at Lance Mosaic, and observationally based measurements like http://www.iup.uni-bremen.de:8084/amsr2/, there are large patches  75% or below.

Which of the following is true?

A) There are large patches of ice 75% or below, in the CAB along the Barents sea.

B) The CAB along the Barents sea is uniformly 80-100% concentration.

If you answered "B" to either question, you are living in Sim City.

Verg

[ktonine]

>> vergent: HYCOM estimates sea ice concentration along the Barents Sea is in the 80-100% range.

And herein lies the rub.

The wording is all wrong.  Misuse of tool.

It should read: HYCOM estimates sea ice concentration for the purposes of its end-users along the Barents Sea is in the 80-100% range.

Using the tool properly makes your questions nonsensical; it would be like comparing apples to oranges.

[Vergent]

So your answer is "B"?

Verg

[Artful Dodger]

If you answered "B" to either question, you are living in Sim City.

Hi Verg,

Close. The intended Users of this model are living in 90m pressurized steel tubes.

More like 688 Attack Sub than Sim City.

Having played both, I can say that I'd much rather err on the low side with ice overhead.

The Navy isn't trying to predict climate with HYCOM. They're trying to not prang the boat. 

[Peter Ellis]

From the validation paper I believe that the Navy model is aimed at forecasting the ice edge for surface ships. Concentration and thickness within the pack are lesser concerns. Definitely not for use by submarines - they won't care whether the ice is 1 or 3 metres when they're cruising around at 20+ down. What they need to know about are ridges, and no model has the resolution to know about those.

Re the MODIS images, I think most people's intuition for eyeballing concentration is appalling. Even the "slushiest" areas in the northern Laptev are close to 80%.   A concentration of 50% is a lot less than you think.

[OldLeatherneck]

If you answered "B" to either question, you are living in Sim City.

Hi Verg,

Close. The intended Users of this model are living in 90m pressurized steel tubes.

More like 688 Attack Sub than Sim City.

Having played both, I can say that I'd much rather err on the low side with ice overhead.

The Navy isn't trying to predict climate with HYCOM. They're trying to not prang the boat. 

Given that HYCOM's intended purpose is strictly as a navigational aid, I still find the animations a very useful predictor of where we will see thinning and/or compaction in the coming few days.

Every time I view the HYCOM thickness animation it makes me think I'm observing a "Sonogram of a Dying Heartbeat".  For certainly, we are watching the death of the Arctic Ice Cap!!

[OldLeatherneck]

..................Definitely not for use by submarines - they won't care whether the ice is 1 or 3 metres when they're cruising around at 20+ down. What they need to know about are ridges, and no model has the resolution to know about those.

Peter,

The submarines do have other needs for that data provided by HYCOM.  Those particular Fast Attack vessels quite often need to approach near to the surface so that they can poke up a variety of antennae for data collection purposes that have nothing to do with observing the weather.

I'd provide more details, however, Artful Dodger would be obligated to have me shot!!

[ktonine]

It's time to give up the exasperating - IT'S ONLY A MODEL !

Pretty much every piece of quantifiable data we have is the result of a model - just that most people don't realize it.  For instance, thermometers, thermistors, thermocouples, etc are used to model temperature.  They apply known physics and allow us to assign a numerical output to the result.  A mercury thermometer never measures temperature.  It has a graduated scale that allows us to see the expansion/contraction of mercury.  With a thermistor we actually measure resistance, for a thermocouple it's voltage.  We have modeled the behavior of materials and used  this knowledge to build instruments that allow us to quantify the world around us. 

Pictures/images aren't reality, they're a 2-D model usually scaled up or down depending upon the size of the subject.  So every satellite image we see is the result of a model - not just the image itself, but also the instrumentation that generated the image PLUS the software that interpreted the raw data. 

Lick your finger and step outside.  Raise your hand in the air.  Direct observation.  Everything else is models all the way down.

***************

HYCOM has many constraints placed upon it.  Significantly, it has to run on widely available computing resources ; it has to generate forecasts - anywhere from days to decades; it is supposed to give the same results across multiple computers for every iteration from the same starting conditions; it has to work in any region of the world.

Do you sea ice concentrations or thickness from ECMWF?
Do you see weekly forecasts from PIOMAS or UniBremen or CT?

HYCOM is the only tool we have that can make a weather forecast and apply it to the arctic and make predictions on how the ice will be impacted.  Those who use and follow HYCOM knew what PAC 2013 was going to do the pack ice in the central arctic.  It is not only a useful tool - it is unique in this respect.

[Artful Dodger]

Given that HYCOM's intended purpose is strictly as a navigational aid, I still find the animations a very useful predictor of where we will see thinning and/or compaction in the coming few days.

Agreed, OLN

I also find the animation very informative of the current trend, especially in hind-cast.

And a boomer captain still wants to know if the ice overhead is 2 m or 5 m before he decides to surface.

Peter, ice ridges can be detected easily with sonar because they protrude. It is the thickness of sea ice with a uniform keel depth that is difficult to determine.

[Nightvid Cole]

I suspect many of us wish PIOMAS would use atmospheric forecasts for the next few days and give us daily updated thickness maps, but, alas, it doesn't.

Perhaps it is the greater sophistication of APL-UW 's model that makes it take more computation time and thus cannot realistically update that much. In which case, it is nothing but the great speed-accuracy trade-off, with HYCOM going for speed and PIOMAS going for accuracy.

Or maybe the issue is that in the era of US government spending cuts/sequestration, barely any science can be done any more because the funding is so hard to get and so unstable. I'm a physics grad student in the US, and believe me, it sucks...

[wili]

"in the era of US government spending cuts/sequestration, barely any science can be done any more"

Yup.

[Vergent]

Disadvantages of HYCOM

HYCOM is a model, not reality. While HYCOM has a high spatial resolution, is very sophisticated, has been under refinement for years, has been tested extensively against in situ measurements and satellite estimates, and uses assimilation to improve its accuracy, it is important to keep in mind that HYCOM is a model. If you have in situ or satellite data available, we recommend you compare it against HYCOM output and form your own opinion about whether HYCOM provides enough accuracy for your situation.

first bold theirs the rest mine

http://code.env.duke.edu/projects/mget/wiki/HYCOM

Disclaimer: This 1/12° Arctic HYCOM/CICE/NCODA system and web page are a demonstration and are not an operational product. NRL is providing the INFORMATION on an "as is" basis. NRL does not warrant or represent this INFORMATION is fit for any particular purpose, and NRL does not guarantee availability, service, or timely delivery of data.

http://www7320.nrlssc.navy.mil/hycomARC/skill_public.html

With this disclaimer, HYCOM is not a navigational aid. Navigational aids are labeled as such.

I'm doing exactly as they say, I'm comparing and forming my own opinion. I'm interested in what the concentratrion/thickness actually is. In the presence of actual measurement and images, basing an argument on the model is foolish.

The main value of Hycom is in its forecasts of ice edge and ice movement. I use these often. They are coupled to a fine weather forecast system.

Lets do what they say, compare HYCOM to observation based products. Hear are lance mosaic, Bremen concentration, myocean concentration, HYCOM concentration.









I draw your attention to the low concentration area east and ENE of Wrangel island. Oops, the model HYCOM has diverged from reality big time. The reason for this divergance can be found on the thickness map. In Hycom's digital world that ice is 1-2 meters thick rather than centimeters of slush.

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn/nowcast/ictn2013071218_2013071200_035_arcticictn.001.gif

My opinion is that the only thing useful on hycom is the ice movement, animations, and forecasts. The ice thickness only gives you the illusion that you know something. From the Healy cam I know that it can be off by as much as 2 meters. It is not a navigational aid for shipping unless they are digital ships inside HYCOM's digital world.

Edits: Image sources and typos.

[ChrisReynolds]

I suspect many of us wish PIOMAS would use atmospheric forecasts for the next few days and give us daily updated thickness maps, but, alas, it doesn't.

Perhaps it is the greater sophistication of APL-UW 's model that makes it take more computation time and thus cannot realistically update that much. In which case, it is nothing but the great speed-accuracy trade-off, with HYCOM going for speed and PIOMAS going for accuracy.

Or maybe the issue is that in the era of US government spending cuts/sequestration, barely any science can be done any more because the funding is so hard to get and so unstable. I'm a physics grad student in the US, and believe me, it sucks...

The PIOMAS team are not funded to provide a daily or even a monthly service. They've provided some monthly thickness data this year, instead of waiting until January 2014 to update 2013, out of their own time because they've noticed the data is being used.

[ChrisReynolds]

Vergent,

All models are wrong, the question is not whether a model is 'right' but whether it is useful. I find HYCOM useful and will continue to use it.

[Frivolousz21]

00z Euro wants yeah you see.

[Vergent]

Vergent,

All models are wrong, the question is not whether a model is 'right' but whether it is useful. I find HYCOM useful and will continue to use it.

Straw man argument. I clearly stated that I use this model frequently. If someone read your response alone they would think otherwise. I did not state or imply "do not use this model" reading your response alone someone would think otherwise.

Specific questions:

Would you base an argument about ice concentration on hycom ignoring Lance, bremen etc?(observation based concentration)

Would you base an argument on ice thickness based on hycom and ignore icebridge and cryosat-2?

You have been repeated making arguments based on PIOMAS having 2012 and 1013 being equal in volume at max, but ignore CRYOSAT-2 observation that the thickness decreased by 8%, while the CT area remained the same.

I stated clearly what I would use from Hycom and what I would not. You, however, spout generalities at the straw man.

Verg

[Peter Ellis]

You know, it's easily possible that PIOMAS and Cryosat are both right, depending on precisely what type of "average thickness" they're reporting.  I believe that PIOMAS reports the median thickness for each pixel - what about Cryosat?  Is it reporting mean, median, mode, or what?  It's very unlikely that there's a normal distribution of ice thicknesses within each pixel  Let's not read too much into the tealeaves here: 8% is only a small discrepancy.

[Vergent]

Peter,

Glad someone is awake. And no I do not blindly accept cryosat as being gospel. But when you get conflicting information, you have to give observation based the edge(the models have a bad record, do I have to post the "you are here" graph once again). It would be nice to have a weather model that went out three months so you can book your vacation. But the above veneration of the hycom model is misplaced. It is mostly BS as I think I have proved, and their disclaimer acknowledges. If Chris wants to hitch his horse to that cart, he is going to... well enough said.

Verg

[Vergent]

Peter,
8% on a one year trend if true, is a cliff.
verg

[Neven]

00z Euro wants yeah you see.

Ah, so we could get that 7-10 high be followed by a GAC-ish cyclone? Sure, why not... 

[Richard Rathbone]

Peter,
8% on a one year trend if true, is a cliff.
verg

Who's claiming it as a trend? WUWT?

[Vergent]

The current trend is the slope of the last two data points. Are you saying it is something different?

CryoSat satellite suggest that the ice pack was 8% thinner in March 2013 compared to March 2012.

http://nsidc.org/arcticseaicenews/

Verg

[ChrisReynolds]

Vergent,

All models are wrong, the question is not whether a model is 'right' but whether it is useful. I find HYCOM useful and will continue to use it.

Straw man argument. I clearly stated that I use this model frequently. If someone read your response alone they would think otherwise. I did not state or imply "do not use this model" reading your response alone someone would think otherwise.

Blather. It's not a straw man, it's me expressing my opinion, starting with generally accepted fact and ending with a statement of intent.

Specific questions:

Would you base an argument about ice concentration on hycom ignoring Lance, bremen etc?(observation based concentration)

Of course not.

Would you base an argument on ice thickness based on hycom and ignore icebridge and cryosat-2?

Don't be daft.

You have been repeated making arguments based on PIOMAS having 2012 and 1013 being equal in volume at max, but ignore CRYOSAT-2 observation that the thickness decreased by 8%, while the CT area remained the same.

Wrong, I have repeatedly said that the thickness distribution for 2013 was less than that for 2012. You must be mixing me up with someone else.

I stated clearly what I would use from Hycom and what I would not. You, however, spout generalities at the straw man.

Utter carp, I merely said I will continue to use it. What you do is your concern.

Verg

My responses in bold.

[sofouuk]

thx to friv for posting relevant to short to medium term arctic sea ice conditions information. the rest is really not doing anyone any favours, regardless of ... well, anything.

[Neven]

Here's a sneak preview at the new SLP Patterns page on the ASIG. I still have to finish it, but I'm a bit tired after spending half of today downloading, cropping, uploading and adjusting html.

But I think it will be useful. At least to me. 

[werther]

Impressive, Neven.
And I know, I've been clipping this sort of thing for months last winter.
During that period, I was mainly interested in 'weird weather' NH patterns. My choice was divided over Geopotential height, 500Mb (the ridge/trough level), 300Mb (the jet level), SLP, 1000Mb temperature. It takes a lot of work, because FI the same scale should be constantly checked.
I see you did 6-day periods. Did you choose that for a reason?
I took 10-day (decadal) periods. I had an idea that would be in best rhyme with the regional movement of the ridges/troughs (just a feel, course I haven't really checked that).
So what now?
SLP is weather, but it reflects best the wind trajectories and insolation. But it is very possible that patterns from the past can not be compared that easily to the present.
Lots of factors have changed. They spawn oppposite consequences.

[Neven]

I see you did 6-day periods. Did you choose that for a reason?

I tried to find a balance between enough information and too much work. In the end I decided to choose the same periods as for the Concentration Maps comparison page, dividing the month up into 6 day periods (and 6 or 7 days at the end of the month depending on how much days the month has). The two week periods I chose for the recent SLP comparison blog post I wrote for the ASIB already conveyed a bunch of useful info (in my view), so 6 days would probably better.

So what now?
SLP is weather, but it reflects best the wind trajectories and insolation. But it is very possible that patterns from the past can not be compared that easily to the present.
Lots of factors have changed. They spawn oppposite consequences.

Yes, indeed. If you look at July 2012 on the SLP Patterns page, you see how after the 12th the weather turned really bad for ice decrease, but area and extent just kept dropping steadily. I wrote about that quite a bit last year, and to me it was even bigger than GAC-2012 because it showed that the amount of ice would continue to decrease, despite the weather. Because it was overall so thin in July that this thinness dominated the rate of loss. I thought I saw some of that in 2011 as well, but July 2012 was very pronounced.

My number 1 question is: will we see that again in 2013? Or has the slow first half of the melting season been enough to mask this shift of power between ice thickness and weather?

That was my main motivation to get this thing set up: to be able to have a quick view at what happened in previous under different/similar circumstances.

[OldLeatherneck]

I have a general question for the many contributors far more knowledgeable than me, particularly when it come to  meteorology.  Although I'm still learning, many of those charts seem more like Rorschach Tests than information I can rapidly digest.  I'm assuming I'm not the only person on this forum that feels the same way.

Would it be of value for someone to start a separate thread entitled "7- 10 Arctic Weather Forecast"?

I'm saying this because quite often comments are made and some charts provided on many of the other threads, however there is often a paucity of description along with these charts.  It's not that I'm not willing to start a thread like this, it's just that I'm not qualified to contribute to it on a regular basis.

[werther]

Going over the MODIS tiles each day, I think I notice structure change going rapidly into the fade out mode.
Sounds cryptic?

I mean, PAC2013 turned (most obvious) tiles r05c03/04(CAB-Chukchi sector), r04c04 (CAB-Laptev sector) and r03c04 (CAB-Kara sector) into structureless swaths of rounded, snow covered floes. Last week, extensive spotted blues marked the snow cover melting out, puddling all floes with melt water. Through the last few days, the floe swaths merged into a seemingly endless cover of speckled grey/blue breccia.

I think this stage was met in 2012 a few days before the final melt out started mid July. The rubbled collage in the breccia starts fading into milky slush. This is already happening on the Chukchi side, N of Wrangel Island.

This looks, although a few days later than last year, exactly the path towards a new record SIE/SIA. This ice is fading out 'in situ'...

[BornFromTheVoid]

I have a general question for the many contributors far more knowledgeable than me, particularly when it come to  meteorology.  Although I'm still learning, many of those charts seem more like Rorschach Tests than information I can rapidly digest.  I'm assuming I'm not the only person on this forum that feels the same way.

Would it be of value for someone to start a separate thread entitled "7- 10 Arctic Weather Forecast"?

I'm saying this because quite often comments are made and some charts provided on many of the other threads, however there is often a paucity of description along with these charts.  It's not that I'm not willing to start a thread like this, it's just that I'm not qualified to contribute to it on a regular basis.

That could be useful, but I'd suggest more of a 4-7 day forecast, as the patterns at 7-10 days will change too often to be useful in most cases.
Alternatively, people could make more detailed descriptions and perhaps annotate the charts they post in here?

[wanderer]

Quick Navy Thickness Comparison:
The positive and negative differences are obvious, but how will it turn out in the end?
I still think it's 50:50 wether we will see a new record or not!

[jai mitchell]

I believe that Obuoy #8 is now afloat.

http://obuoy.datatransport.org/monitor#buoy8/webcam

observe the reorintation to vertical and the repositioning of the ice in the frame.  Previous frames showed deep blue next to the buoy.

[jai mitchell]

Yep,

http://obuoy.datatransport.org/monitor#buoy8/gps

Kerplop at 0100 UTC on July 16th.  Also the webcam orientation has rotated clockwise by about 10 degrees since last update.

[ChrisReynolds]

Having discovered that correlation is used to compare model output with observed climate/weather patterns (in Taylor Diagrams), I am now relatively content with using correlation to provide a numerical index of the presence of the summer circulation pattern post 2007. This will have to do anyway because I am now satisfied I don't know enough to use EOFs.

The following plot shows the summer pattern, which is a new pattern post 2007. The plot is calculated as the difference from long term mean pressure for summers from 2007 to 2012, the resultant data set has then been averaged to bring out the strongest repeated features, and plotted.



This pattern was strongly present during 2012.


However this June the pattern had reversed.



Which is what has lead to slow volume/area/extent loss in June.

I have downloaded the data used to make those sorts of images for all months from June to August over the years 2000 to 2013 (June). Loaded into a spreadsheet as tables these were then correlated, each in turn, with the numerical data behind the pattern in the first graphic of this comment. This produced a correlation number, the results being tabulated below.

A correlation of 1 means the SLP plots are identical. A correlation of 0 means there is no relationship. A correlation of -1 means that the two SLP plots are opposites, in the sense of one being the negative of the other.



We're now well into July, even without July's data with which to do a similar correlation, it is clear that July will have either a low correlation or a negative correlation. The only feature which could cause a small positive is the high pressure over the Arctic (which is common to the top image of this comment).

[ktonine]

Chris - I'm not sure that this really explains anything.

The coastal waters on either side of the Bering Strait are supposedly neutral in 2013 compared to 2012 or post-2007; yet this is one of the areas - especially the Beaufort side - where 2013 has not seen anywhere near the same area/extent losses.

More importantly it neglects the diurnal cycle and the effect it has on OLR.  High pressure during the day and low pressure at night is conducive to melt.  Take the exact same pressures and flip-flop them diurnally and you create the opposite melt effect even though the average pressure would be the same.

Perhaps I'm missing something obvious, but the only thing I take away from this is that the weather in 2013 has been different - but I don't think there has been any disagreement on that.

[ChrisReynolds]

Ktonine,

It's not just been different, it's been radically different, stunningly different. This year has seen weather conditions that have overcome marginally worse ice conditions than 2012 and have severely retarded the melt season. Considering the state of the ice this winter, whatever has had the power to retard the melt season has been very powerful. And here we see it.

The diurnal cycle isn't really relevant, although I see what you mean. The summer pattern from 2007 to 2012 causes a strong dipole anomaly over the pack, that has been absent this year. What we're seeing in this year's slow melt is the power that this pattern and the resultant dipole anomaly have had over the other post 2007 years, this year it has been absent and we're seeing the result.

[ChrisReynolds]

GFS shows the Barents low spreads across the Arctic, before intensifying around next Wednesday, and persisting through to Friday.

[jdallen]

GFS shows the Barents low spreads across the Arctic, before intensifying around next Wednesday, and persisting through to Friday.

Possible GAC2013?  Not that it would have to be that intense to stir the current "bowl of ice cubes" up pretty seriously.

[ChrisReynolds]

This low is forecast to be about 995mb central pressure, last years August Storm was below 985mb.

Furthermore, using SSMIS (Bremen AMSR-2 doesn't start until 24 July 2012):

Here's 18 July 2013:
http://www.iup.uni-bremen.de:8084/ssmisdata/asi_daygrid_swath/n6250/2013/jul/asi-SSMIS-n6250-20130718-v5_visual.png

And 18 July 2012:
http://www.iup.uni-bremen.de:8084/ssmisdata/asi_daygrid_swath/n6250/2012/jul/asi-SSMIS-n6250-20120718-v5_visual.png

Same time last year the ice was in a worse state over the Pacific sector.

[jdallen]

This low is forecast to be about 995mb central pressure, last years August Storm was below 985mb.

Furthermore, using SSMIS (Bremen AMSR-2 doesn't start until 24 July 2012):

<snippage>

Same time last year the ice was in a worse state over the Pacific sector.

Chris;

Please excuse if that came across as wild-eyed doomsaying.  I was not trying to suggest the impending doom of the ice by way of a repeat of 2012.  That said, 995 is a pretty low pressure, and should kick up some fairly good circulation.   My observations was more musing over what a reasonable cyclone would do to the ice in the Beaufort (and elsewhere, for that matter) in its current state.