The 2015 melting season

[Jim Hunt]

The entire NWP will melt.  It's shatterin now while it gets super torched.

A video of the current setup in the NW Passage:



Cross posted from:

http://forum.arctic-sea-ice.net/index.php/topic,762.msg57101.html#msg57101

[ChrisReynolds]

A new page and we're back on sea ice. 

Sea Ice Sailor,

I have a suspicion that Beaufort might be surprisingly resilient this year and that the melt there will remain only slightly greater than average.

Greater than *which* average? 1979-2000? 1981-2010? 2007-present?

1981 to 2010.

I use that period so it matches with NCEP/NCAR anomalies, it makes analysis easier.

***

Currently for Beaufort:

1) Area anomalies have been slightly rising since mid June.

2) Extent anomalies have been rising since late May.

3) Compactness anomalies are the same as in mid May, and rose slightly before falling during the intervening period.

How to interpret? Considering the anomalies being the difference from an average seasonal cycle, during the melt season: Rising anomalies means loss is less than average. Anomalies being flat between two dates means the loss between those two dates has been average.

So despite rapid loss from other regions over this month, losses have not picked up since then. and remain average. Even compactness does not suggest future large losses are to be expected.

Note that compactness anomaly for the peripheral seas of the Arctic Basin (Beaufort round to Laptev) is tracking both 2007 and 2012. Compactness anomaly in the ESS is at the same levels as 19 June, but that was a downward spike of one day (winds? cloud?), now compactness has been low for over a week and is only matched by 2007 and 2011, ESS extent anomaly has fallen from 0 (average) to -0.2M km^2 over the last 14 days, in 2007 and 2011 the same thing happened at different times around now, 2007 was earlier, 2012 was later.

GFS shows the -ve AO high pressure persisting and transient low pressures along the Siberian coast, with a low tendency over the north Atlantic / Scandinavia/Barents that might aid Fram export.

Things are looking really good. 

[Andreas T]

.......
There is a major dipole right now crushing the CAB and we have 19 days left above 400W/M2 which is high enough for major melt.

the problem with quoting that 400W/m2 figure is that it leaves out the outgoing radiation which is also higher when the sky is clear
this i from an old post (by Chris) on this thread which I found again recently
Re: The 2014 Melting Season
« Reply #1256 on: June 14, 2014, 08:11:51 PM       

this illustrates the same thing I think source http://faculty.atmos.und.edu/dong/papers/10.1007_s00382-013-1920-8.pdf

the Short Wave UP curve shows changing albedo over the summer nicely I think.

[jdallen]

.......
There is a major dipole right now crushing the CAB and we have 19 days left above 400W/M2 which is high enough for major melt.

the problem with quoting that 400W/m2 figure is that it leaves out the outgoing radiation which is also higher when the sky is clear
this i from an old post (by Chris) on this thread which I found again recently
Re: The 2014 Melting Season
« Reply #1256 on: June 14, 2014, 08:11:51 PM       

the Short Wave UP curve shows changing albedo over the summer nicely I think.

Not arguing your facts, Andreas, but I think the core of Friv's point wasn't the scalar value but rather the qualitative - that we still have three weeks of insolation which are near as intense as that seen over the last two months.  Add in the pretty optimal conditions for picking up that radiation along with fairly high temperatures via heat imported from *elsewhere*, and I think you may better get his point.

In short, we have coming up a serious hard energetic "shove" to the melt, by way of normal insolation combined with better than usual melt weather.

[seaicesailor]

A new page and we're back on sea ice. 

Sea Ice Sailor,

I have a suspicion that Beaufort might be surprisingly resilient this year and that the melt there will remain only slightly greater than average.

Greater than *which* average? 1979-2000? 1981-2010? 2007-present?

1981 to 2010.

I use that period so it matches with NCEP/NCAR anomalies, it makes analysis easier.

***

Currently for Beaufort:

1) Area anomalies have been slightly rising since mid June.

2) Extent anomalies have been rising since late May.

3) Compactness anomalies are the same as in mid May, and rose slightly before falling during the intervening period.

How to interpret? Considering the anomalies being the difference from an average seasonal cycle, during the melt season: Rising anomalies means loss is less than average. Anomalies being flat between two dates means the loss between those two dates has been average.

So despite rapid loss from other regions over this month, losses have not picked up since then. and remain average. Even compactness does not suggest future large losses are to be expected.

Note that compactness anomaly for the peripheral seas of the Arctic Basin (Beaufort round to Laptev) is tracking both 2007 and 2012. Compactness anomaly in the ESS is at the same levels as 19 June, but that was a downward spike of one day (winds? cloud?), now compactness has been low for over a week and is only matched by 2007 and 2011, ESS extent anomaly has fallen from 0 (average) to -0.2M km^2 over the last 14 days, in 2007 and 2011 the same thing happened at different times around now, 2007 was earlier, 2012 was later.

GFS shows the -ve AO high pressure persisting and transient low pressures along the Siberian coast, with a low tendency over the north Atlantic / Scandinavia/Barents that might aid Fram export.

Things are looking really good. 

Beaufort ice diverged toward the coast during last half of June, halting extent losses. I guess it's not been good for MYI floes to get closer to the warmer coast waters, while ocean been opening up between them. Bottom melt has been picking up already in some areas, perhaps over the whole region? Buoys (the very few) do not contradict this.

Granted it's been mostly cloudy during July avoiding probably much faster melting. 

Compaction would just somehow reverse the previous diverging of the ice, only that now it is much less area than one month ago. Anyway, really interesting.

EDIT: Buoys if I am told well were installed over MYI. It says something about the water temperature that bottom melt has been substantial taking into account the higher melting temperature for MYI.

[Jim Hunt]

Currently for Beaufort

Here's a video for that neck of the Arctic woods also:

[seaicesailor]

Currently for Beaufort

Here's a video for that neck of the Arctic woods also:

One pic is worth 1000 words. Nice vid, thank you!!

[opensheart]

The Hudson Bay and Eastern North America has been cool for awhile.    I've watched the weather maps.  There usually has been two 'fronts' protecting Hudson Bay area.   The lower one has been parked accross Chicago - Cincinnati for a while.   But today it has broken down.   It is upper 90's F. here in Cinci today.  Warmest day thus far this summer.   Feels like 104 F.   And the stationary fronts look like they have turned into warm fronts and are advancing accross Hudson Bay.   If I read the below temps correctly,  melt on Hudson Bay should increase.

Hope this attached picture works.

[cesium62]

A new page and we're back on sea ice. 

Sea Ice Sailor,

I have a suspicion that Beaufort might be surprisingly resilient this year and that the melt there will remain only slightly greater than average.

I'll take that bet.  With El Nino heat flowing through the Bering Strait and over Alaska, the Beaufort will suffer greatly even with the extra MYI present.  The volume melt will be huge.  The extent melt will be as high as it gets:  the Beaufort will melt out.  ;-)

[oren]

Currently for Beaufort

Here's a video for that neck of the Arctic woods also:

Thanks Jim, sums it up nicely.

[Neven]

Absolutely great vids, Jim. I'll repost them on the ASIB. You're using Uni Hamburg maps, right (the ones with 3.125 km resolution)?

[Neven]

I also have some bonus info looking ahead, the SAT and SLP comparison map for July 16th-31st I'll be using for next month's July analysis:



This map perfectly shows melting momentum in action, in my opinion. Practically every year saw cyclones taking over the show during the latter half of July, except for 2007. And if you look carefully at the trend lines on the IJIS SIE graph for the last 10 days of the month, you see all of them levelling off:



The only years still going strong, are 2007 and 2012. 2007 because the dipole persists, causing plenty of melting, compaction and transport. 2012 because of all the melting potential built up in preceding weeks, lots of melt ponds, high SSTs, also helped by low volume at the start of the melting season, of course.

Rebound years 2013 and 2014 almost come to a complete standstill during this period (no melting momentum built up during cold and/or cloudy May and June), 2010 already had problems in the first two weeks of July, but 2011 perfectly shows how a change in weather conditions immediately puts a brake on rate of decrease.

I'm pretty certain the same would happen this year, but as we know, the forecast shows a prolongation of current weather conditions:



The forecast for days 7-10 show the high moving over to Siberia, but this nonetheless means 6 more days of melting momentum build-up, with the heat starting to bleed through on the SIA and SIE charts. It will be interesting to see what happens when weather conditions switch, and whether this late melting momentum can sustain the rates somewhat. If weather conditions don't switch, I'll start believing 2007 and 2011 can be overtaken.

Will the second half of July this year produce a SLP map with some green and yellow in or near the centre of the Arctic, for the first time since 2007?

[Jim Hunt]

You're using Uni Hamburg maps, right (the ones with 3.125 km resolution)?

Thanks Neven, and I am indeed. Click through to YouTube and "Show more"!

I'm working on an NSR one also. Here's some I prepared earlier:

http://GreatWhiteCon.info/2015/01/is-the-economist-being-economical-with-the-truth-about-arctic-sea-ice/

[JER]

I'm not sure where to post this, so I apologize if this isn't a good place. (I also just posted it on the ASIB under the PIOMAS discussion.)

There's a new study just out that is of interest and concern regarding the impact of stored heat from the summer melt season on Arctic sea ice growth in winter: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL064541/abstract

From the abstract: "It is shown that the release of solar heat stored following summer 2007 was sufficient to have reduced sea-ice thickness at the end of the 2008 growth season by about 25%."

[oren]

I'm not sure where to post this, so I apologize if this isn't a good place. (I also just posted it on the ASIB under the PIOMAS discussion.)

There's a new study just out that is of interest and concern regarding the impact of stored heat from the summer melt season on Arctic sea ice growth in winter: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL064541/abstract

From the abstract: "It is shown that the release of solar heat stored following summer 2007 was sufficient to have reduced sea-ice thickness at the end of the 2008 growth season by about 25%."

This was already posted in The Slow Transition thread.

[JER]

Okay. Sorry.

[Jim Hunt]

I'm working on an NSR one also.

Here's the final part of the trilogy:

http://GreatWhiteCon.info/resources/arctic-sea-ice-videos/summer-2015-videos/#NSR



Perhaps there should be a poll on whether the Northwest Passage or the Northern Sea Route will open for business first? Here's the current list of 477 vessels ready and waiting to voyage along the NSR:

http://asmp.morflot.ru/en/razresheniya/

and here's the long term forecast as of March 23rd:

http://www.arctic-lio.com/node/230

[slow wing]

Really enjoying the great analysis and graphics in this exciting part of the melt season.

Years 2007 onwards are actually fairly close at mid-July and it is the second half of July where 2012 in particular streaks away, as Neven posted and showed graphically above.

The daily University of Bremen concentration map has been posted. Beaufort, Chukchi & the Siberian side continue to deteriorate.

The 80 degrees North line indeed looks a good demarcation line between the zone outside where concentrations are waning and, on the other hand, inside it the high concentrations have scarcely been dented on the Pacific and Siberian sides.

Will we end up with a fairly roundish ice distribution at minimum this year?

Click on the map below to also sample the two preceding days...

[ChrisReynolds]

The Arctic Dipole flow for July so far...



http://dosbat.blogspot.co.uk/2015/07/hello-dipole-my-old-friend.html

[BornFromTheVoid]

Looks like those winds will continue for another 5 days at least.

[funky-shadow]

Hi there,

longterm lurker and fascinated by the speed of change in the Arctic.

Just in addition to what Neven analysed some posts above:
Following this link http://www.dh7fb.de/noaice/min13akt.gif the speciality of the upcoming 7days becomes even more obvious. each year since 2007 here lost room vs climatology while this year gains momentum in the actual dipole state of circulation with embedded warmth.
 

[plg]

Some curious statistics:

NSIDC has lost an average of more than 100'000 km2 per day since June 25, i.e. a 24 day stretch averaging over a century. IJIS/SIE is not quite as dramatic, average loss over 100'000 since July 2, i.e. 17 days.

I haven't (yet) checked how unusual this is (if it is).

[Nightvid Cole]

Really enjoying the great analysis and graphics in this exciting part of the melt season.

Years 2007 onwards are actually fairly close at mid-July and it is the second half of July where 2012 in particular streaks away, as Neven posted and showed graphically above.

The daily University of Bremen concentration map has been posted. Beaufort, Chukchi & the Siberian side continue to deteriorate.

The 80 degrees North line indeed looks a good demarcation line between the zone outside where concentrations are waning and, on the other hand, inside it the high concentrations have scarcely been dented on the Pacific and Siberian sides.

Will we end up with a fairly roundish ice distribution at minimum this year?

Click on the map below to also sample the two preceding days...

00z ECMWF suggests that we will have a much clearer view of much of the CAB on several days this week, due to the large dome of High pressure.

Be patient (I have trouble with this myself on occasion!)

[Jim Pettit]

Some curious statistics:

NSIDC has lost an average of more than 100'000 km2 per day since June 25, i.e. a 24 day stretch averaging over a century. IJIS/SIE is not quite as dramatic, average loss over 100'000 since July 2, i.e. 17 days.

I haven't (yet) checked how unusual this is (if it is).

For IJIS SIE, it's not that unusual. 2007, 2011, and 2013 all showed larger daily average decreases over the same 16-day stretch. The average over the past ten seasons: 92k.

(FWIW, only 2007 managed to average a century-plus decrease for every day in July. Even 2012, with 11 century breaks and one double-century break, wasn't able to accomplish that feat.)

[ChrisReynolds]

Looks like those winds will continue for another 5 days at least.

They really show up in the average, the high can stay in place but the lows tend to pass along then die.

I think that although the rest of the summer may not be as strong as that we will see the dipole persist into August. 2007 to 2012 show that persistence is not gauranteed, but once the pattern starts it tend to keep coming back and show in the JJA average. All we need is for the Arctic Ocean high to persist.

[iceman]

I'll take that bet.  With El Nino heat flowing through the Bering Strait and over Alaska, the Beaufort will suffer greatly even with the extra MYI present.  The volume melt will be huge.  The extent melt will be as high as it gets:  the Beaufort will melt out.  ;-)

Looks to me like the source of heat is more from the anomalously warm waters in the NE Pacific, which predate the current El Nino.  Heat advection through Bering doesn't appear especially high so far this season, and the blast coming up next week will impact ESAS more than Beaufort.
     The MYI in Beaufort probably has had some "protective arm" effect to date, but it will be further weakened by another week of warmth coming off the Canadian Archipelago region.  Agreed on volume loss, and not looking too good for area/extent either.

[Jim Hunt]

Mid month has been and gone, so I'm updating my Ice Mass Balance buoy temperature profiles. First up is 2014G, currently located at 77.89 N, 163.08 W. The top and bottom sounders have never worked properly, but the thermistors suggest to me that there's currently less than 50 cm of solid ice under the buoy:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2015-imbs/#2014G-Temp

[Jim Hunt]

Wadham's prediction of 1M km^2 is best put in context by the fact that even though we have some record low area/extent/compactness, none of those figures are so much wildly lower than other recent years that they suggest something as extreme as a 1M km^2 September extent.

Prof. Wadhams informs me that:

My SIPN prediction is an outlier but it is in fact what is predicted by the 5-year trend in ice volume in September. In 2013 and 2014 the volume in summer came in above this trend, but since then we have started a new El Nino which tends to increase air temperatures more. I am just staking this area out as a marker, and expect to be shot down in flames.

[ChrisReynolds]

Wadham's prediction of 1M km^2 is best put in context by the fact that even though we have some record low area/extent/compactness, none of those figures are so much wildly lower than other recent years that they suggest something as extreme as a 1M km^2 September extent.

Prof. Wadhams informs me that:

My SIPN prediction is an outlier but it is in fact what is predicted by the 5-year trend in ice volume in September. In 2013 and 2014 the volume in summer came in above this trend, but since then we have started a new El Nino which tends to increase air temperatures more. I am just staking this area out as a marker, and expect to be shot down in flames.

I had argued over at Neven's blog in response to a comment by Larry Hamilton that I thought this was what Wadhams was doing. Then I found that video in which his statements gave the clear impression it was an expectation.

Anyway, even without the crappy weather of 2013/2014 we'd still have been way above 1 million kmsq.

It was 2015 +/-3 years wasn't it? Let's just see what happens over the next three years. 

[Neven]

It was 2015 +/-3 years wasn't it? Let's just see what happens over the next three years. 

If you're referring to Maslowski's model, it's 2016 +/- 3 yrs.

[OSweetMrMath]

I've been getting into Wadhams' prediction a bit in the comments on http://realclimate.org . Restating my basic argument from a few days ago, hitting Wadhams' prediction of less than 1 million sq km average September NSIDC extent requires an average daily loss of 140 thousand sq km from now until the first week of September.

This is clearly ridiculous. Sustained loss at that rate is unheard of even at the peak of the season, and the loss rate typically slows through August.

I feel better with Wadhams setting it as a marker rather than claiming it as a prediction for reality, but I think he has been stating it in places where he's not making that distinction. But I also think it's a pretty lousy marker. The "trend" may say that's what will happen, but looking at the actual extent so far this year should lead to the conclusion that the trend is not a useful prediction. (Also, I want more details on how he's computing that trend. I'd settle for methodology in absence of his data.)

With my predictions, I'm aiming for the most likely outcomes. I get the appeal of predicting worst case scenarios, but I question the value of presenting the worst case as a probable outcome. I don't see any value in making predictions which are clearly worse than can physically happen.

[cesium62]

Some curious statistics:

NSIDC has lost an average of more than 100'000 km2 per day since June 25, i.e. a 24 day stretch averaging over a century. IJIS/SIE is not quite as dramatic, average loss over 100'000 since July 2, i.e. 17 days.

I haven't (yet) checked how unusual this is (if it is).

Eyballing the arctic sea ice index (https://cider.corp.google.com/#ws=windshield_django_1_5&sid=aokR3rxKK3xGYZsNTyrY3Wrr6pQ%3D) 2013 had a steeply falling stretch near this time of year.  2015 looks slightly steeper than in recent years and than the average, but not a whole lot steeper...

[cesium62]

I'll take that bet.  With El Nino heat flowing through the Bering Strait and over Alaska, the Beaufort will suffer greatly even with the extra MYI present.  The volume melt will be huge.  The extent melt will be as high as it gets:  the Beaufort will melt out.  ;-)

Looks to me like the source of heat is more from the anomalously warm waters in the NE Pacific, which predate the current El Nino.  Heat advection through Bering doesn't appear especially high so far this season, and the blast coming up next week will impact ESAS more than Beaufort.
     The MYI in Beaufort probably has had some "protective arm" effect to date, but it will be further weakened by another week of warmth coming off the Canadian Archipelago region.  Agreed on volume loss, and not looking too good for area/extent either.

Widneus' graphs (https://sites.google.com/site/arctischepinguin/home/amsr2/grf) suggest that the Bering and Chukchi seas lost extent early this year (although the graphs don't show an average so I may be fooled by looking at inadequate data), suggestive of anomalously high heat flowing through the Bering this year.  I hadn't looked at the Beaufort graph recently...  ;-)

[ChrisReynolds]

It was 2015 +/-3 years wasn't it? Let's just see what happens over the next three years. 

If you're referring to Maslowski's model, it's 2016 +/- 3 yrs.

Frankly I don't know whether it's that or the calculation based on PIOMAS, which I think Wipneus has done. Sorry to be vague on this but as I have never been impressed I have never paid much attention.

EDIT - I do have in my mind 2015 though, that has come from somewhere.

[Bob Wallace]

... hitting Wadhams' prediction of less than 1 million sq km average September NSIDC extent (in 2015) requires an average daily loss of 140 thousand sq km from now until the first week of September.

Very unlikely we would see as little as 1 million sq km extent in September of this year.  But let's look at his prediction of reaching that level by September of 2019 (2016 +/- 3 years).  Suppose 2015 turns out to be The Year of the Great Meltback, removing the buildup of 2013 and 2014 and putting us back at exponential trend levels.



Then assume we simply have more of the same of what we experienced prior to 2013/14.  It's a cruise to zero.

(Do I need to point out that I added the purple line?)

[OSweetMrMath]

Looking at PIOMAS, the volume on June 30th was 15.263 thousand cu km. The maximum loss on record for the period from June 30 to the minimum is 11.3 thousand cu km, and the loss has exceeded 10 thousand cu km only once in the last ten years. Why should I consider the possibility of a loss of 12 thousand cu km, which would be necessary to get down to the trend line?

The purple line already represents an extreme year over year change, with only one other year in the record coming close to that much loss. Since then, we have nine months of data which are utterly failing to support that prediction.

Keep in mind that the trend line has been recomputed each year. The trend line in 2012 predicted that 2013 would be at 1.9 thousand cu km, and the volume would hit 0 in 2015, with a "confidence interval" of plus or minus 3 years. (That interpretation requires an abusive reading of the confidence interval on the graph. 95% refers to a range of volume on a fixed date, not a range of dates for a fixed volume.) (See https://sites.google.com/site/arctischepinguin/home/piomas/archive/piomas2012/piomas-trnd6.png for the graph.)

The exponential trend line was virtually unchanged between 2010 and 2012, but the 2013 data pushed it up quite a bit. The 2014 data pushed it up further, and the 2015 data will push it up again.

The exponential trend produced shocking results in 2010-2012 (both in terms of accuracy and in terms of the possible future) but has not fared well since then. It may have outlived its usefulness.

[Bob Wallace]

So drop the volume back to the trend line over two years. 

I'm not making a prediction.  I'm pointing out that the possibility for hitting 1 million sq km extent by the end of the 2019 melting season is still greater than zero.

Over years we see the ice becoming less of a monolith and more of a punch bowl of ice cubes.  As we lose the many-meter thick ice and see the pack break into hunks that can be floated into warmer water our ability to predict melting patterns based on past melting behavior diminishes.  We're likely heading toward a day like those we see with other larger bodies of ice. 

One day the ice simply melts.

[OSweetMrMath]

I'll post a similar disclaimer to the one I ended up posting at realclimate.org :

I think it is reasonably probable that the September extent will reach 1 million sq km by 2030. To pick a number, the probability is 40%.

I think it is highly improbable, but not impossible, that the September extent could reach 1 million sq km by 2020.

I think it is impossible that the September extent will reach 1 million sq km this year.

I am opposed to predictions that the extent will reach 1 million sq km this year, even as "markers".

I do not see why I should have to take predictions based on curve fitting seriously when they have already failed and been revised several years running.

[greatdying2]

Speaking of warm waters, Mackenzie discharge at ~10C are reaching very close to the ice edge... and into the path of some very large chunks of ice.

 

[jdallen]

...
I think it is impossible that the September extent will reach 1 million sq km this year.
...

Pretty much; the rest of the season simply can't provide enough heat at this point, and what is there already won't be enough to carry off the rest of the ice.

I'd put the probability of under 1 million by 2030 quite a bit higher than you do, however.  To put a number on it, as you do, I'd say 95%.

[slow wing]

I think it is impossible that the September extent will reach 1 million sq km this year.

Impossible is a strong word. It might be reasonable if there simply wasn't enough heat around to melt the current volume of Arctic sea ice, but that is not the case.

Waldhams claims the Arctic ice is largely 'rotten', so has little mechanical strength and resistance to crumbling to slush.

Lots of heat influx to the Arctic in July and August followed by a strong storm could presumably reduce the extent below 1 million sq km this year. Unlikely but not impossible.

[Bob Wallace]

If you look at the 'central bowl' extent today you will see that 2015 is tied with 2012.  Something happened after this date in 2012 which drove its final level to the record low.



The Arctic Sea is now vulnerable to strong weather events.  Imagine a strong and persistent weather pattern that shoved ice out the Fram Straight for a few weeks in a row.

Or imagine an earlier fire season in Alaska, Canada and Siberia which darkened and melted out the snow cover earlier, followed by a blazing Sun June.

We're not talking certainty but possibilities.  A couple of low probability but very strong events could melt out the Arctic.  They might never appear, but they could appear....

[Buddy]

Unlikely but not impossible.

Ditto....maybe even a little stronger.....like "highly unlikely."

And this is coming from someone who expects a "near record".....or new record low ice.

[jdallen]

Unlikely but not impossible.

Ditto....maybe even a little stronger.....like "highly unlikely."

And this is coming from someone who expects a "near record".....or new record low ice.

I tend to disagree; I think impossible is the correct adjective.  The energy budget won't support a melt out this year.

Now, that said, considering the current weather...

The dipole predicted does appear to be set up and chugging along nicely.  While people are excited about the prospect of increased export out of the CAB through the Fram and past Franz Josef into the Barents, I've been looking at surface wind speeds and vectors in the Beaufort.

It would appear that the dipole will be pushing that disconnected scatter of MYI out of its bastion into warmer waters close to the coast - water which someone elsewhere pointed out may be as hot as 10C.  Seems the Grinder may be about to go to work.

In other news, the fracturing in the West outlet of the NWP has spread eastward at least another 150KM.

[Greenbelt]

Remarkable thing to me about this July is the consistent positive temperature anomaly in the Canadian Archipelago. And the forecast maintains the high temps in that region for next week.

[slow wing]

I think impossible is the correct adjective.  The energy budget won't support a melt out this year.

I'm surprised. Where is this energy budget you are referring to and what are the uncertainties?

It must presumably include terms for:
direct sunlight
longwave radiation
heat in air flowing into the Arctic
water vapour in that air
heat inflows from sea currents and rivers
heat already in water under the ice

The values of all of these terms are highly uncertain (both means and uncertainties) so I'm skeptical on setting an 'impossible' upper limit on their sum below what would melt out all of the ice.

(I anyway had the impression that there would easily be sufficient energy to melt all the ice even using reasonable values for the above contributions. The issue is getting that heat to the ice. That's less of a problem when there is a storm and the ice turns to slush.)

[Tommy]

Area unimportant.
Ice depth is all that really matters, no?

[slow wing]

Hamburg has updated and we can now do the 'July 19' sea ice area & concentration comparison by years on the excellent display set up by Neven:

https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0719


On this comparison, 2015 is looking way ahead of both 2013 and 2014 and somewhat closer to most or all of the preceding years within 2007-12.

[jdallen]

I think impossible is the correct adjective.  The energy budget won't support a melt out this year.

I'm surprised. Where is this energy budget you are referring to and what are the uncertainties?

It must presumably include terms for:
direct sunlight
longwave radiation
heat in air flowing into the Arctic
water vapour in that air
heat inflows from sea currents and rivers
heat already in water under the ice

The values of all of these terms are highly uncertain (both means and uncertainties) so I'm skeptical on setting an 'impossible' upper limit on their sum below what would melt out all of the ice.

(I anyway had the impression that there would easily be sufficient energy to melt all the ice even using reasonable values for the above contributions. The issue is getting that heat to the ice. That's less of a problem when there is a storm and the ice turns to slush.)

Yes, Slow Wing, all of that; further, at any given moment there is more than ample energy in the Arctic Ocean to melt *all* of the ice, even in the middle of winter. 

It is a question of how probable that event would be.

We are arguing semantics over usage of a word.  Let us agree to disagree here. I think if we compared notes, we'd find we both think the same thing; we just have different ideas over word choice to describe it.

[slow wing]

Fair enough