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Messages - jdallen

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Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 19, 2018, 06:15:57 PM »
Suddenly a really cold spell in the northern Bering Sea and into the Chukchi ?
From the looks of it, not really.

The satellites show a far amount of anchored pack ice along the Bering shore of Alaska, which explains some of the"blue", but actually mostly the image suggests mostly normal to warm temps over the Bering. 

Interior AK looks colder, but not over the water. 

The Chukchi looks slightly cooler, but doesn't exactly look like a cold snap.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 18, 2018, 09:57:55 PM »
One has to wonder how the volume being exported over the last 50 days compares to that newly created (and retained) by ice thickening.
Your Kara ice intrusion animation speaks to that.  It's new ice which is displacing 2nd year+ ice in the CAB, quite definitively.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 18, 2018, 05:12:14 AM »
Dawn at Little Diomede yesterday (arrow). WorldView will be showing some of the Chukchi soon in its visible and IR channels. That may be soot in the lower left and center, third image.
Indeed, returning with effectively no ice in the Bering to keep albedo high and prevent heat uptake.

The exchange is still strongly postive outbound, but in a few weeks it will start to balance out, sooner if we continue to see moisture and heat inputs from further south into the Bering.

I'm wondering now if we may see exceptionally early opening of the Bering strait and Chukchi - possibly as early as late March.  I'm also wondering what consequences *that* could have on the ESS and Beaufort as a cascade.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 18, 2018, 04:57:45 AM »
The thermal conductivity of snow is highly variable, just one among all the other variables quoted by A-Team. Given the paucity of data (rightly often bemoaned by A-Team) those teams doing the modelling are right on the edge of doability. But more credit to them for giving it a go.
The Beaufort Sea study I referenced elsewhere came up with an averaged value of about .33, which generalized effect of drifting, compaction, etc.

The value for new snow (A-Team's "powder") is much lower - .071.  Even slab snow (which has compacted into sheets which resist blowing is lower at .29.  However, the extra I think accommodates what A-Team was driving at in his comments.

As I'm pondering ways to apply this to gridded data, I will have to fudge and will likely choose to err in favor of the effective measured coefficient, as it similarly summarizes widely varying conditions across the pack.

As imperfect as that is, If we can start from some sort of direct measurement I agree with A-Team that this would put estimation a step up from the models, however clever.

Arctic sea ice / Re: Latest PIOMAS update (January update)
« on: January 16, 2018, 05:44:23 AM »
Having a mad thought (tm) about ice thickness calculations/estimation, as I ponder ways to track heat transfer through the arctic..  It ties back to a few questions.  Bear with me, this may be redundant.

(1) Is snow depth on ice something which can be easily derived?  Are there gridded data sets which are able to provide that based on some sort of reasonably reliable sensor?

(2) Can we reasonably derive the ice/snow surface temperature either through estimated 2M temperatures?

(3) Alternatively, how good is the gridded temperature as derived from observed upwelling IR?

(4) Under the ice, can we reasonably assume the ice-water interface temp to be -1.8C?

It follows by this that we may be able to proxy ice thickness by comparing the heat flow as indicated by the observed temperature of the snow surface and subtracting out estimated flow through the snow using an average thermal transfer value, and then plugging that into an inverted equation for heat flow through ice, solving instead for thickness.

Anyone aware of research/modelling utilizing something like this strategy?  I'd rather not re-invent the wheel here.

I may want to start a separate thread for this, but I wanted to plant a seed here first.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 16, 2018, 04:59:50 AM »

...this is very incorrect.

Snow in southern latitudes does a much better job of reflecting sunlight back into space and reducing overall heat anomalies vs. snow in sunless high-latitudes (that are probably covered anyways).

Additionally, snowfall over thin ice can do a better job of insulating heat underneath, paradoxically creating warmer conditions if heavy snows occur when initial refreeze completes.

Yeah, then we should be heading into a Rebound Year according to ur Analysis.

All that snow and cold should have stayed inside the Arctic Fridge. But no, it is escaping into lower latitudes, where it will disappear and fast. Causing flash floods, inundations and a lot of erosion- not to mention wildlife damage.
Snow isn't escaping, cold is, which effectively detonates on contact with moist air at the mid latitudes when the air masses collide.  There's still plenty of moisture of snow pack on the ice, as this chart below seems to indicate.  20-40CM is plenty of blanket to slow down heat transfer significantly.  That's equivalent to a 10CM thick wall filled with fiberglass insulation, more or less.

Also found this cool article studying thermal transfer through snow on ice in the Beaufort:

Over all, average thermal conductivity  of snow pack on arctic ice is about half that of the ice beneath it.  QED/Rule of thumb would be - 40CM of snow slows down ice thickening about as much as 80CM of ice.

Now to find some of last year's snow thickness plots from around this time...

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 14, 2018, 10:48:39 PM »
According to Environment Canada the southernmost of the two cyclones off Greenland was down to a MSLP of 942 hPa at 12:00 UTC:
I've been browsing the various model runs for 500hpa on tropical tidbits, and they're very consistent.  There's a persistent trough that for the next few days is going to rapidly transport warmer mid-latitude air masses past NW Europe into the Barents/Kara and then into the central Arctic proper.  The longer term/less reliable (96 hours +) models have the trough oscillating back and forth across the N. Atlantic, but generally persisting with a deep flow from further south into NW Europe and the Atlantic front of the Arctic.

On the Pacific side the trough(s) are not quite as persistent, but are sending consistent flow into the Bering and Alaska proper, but with some transport of heat across to the Beaufort and Chukchi.  Between waves, heat and rain, we may actually see serious decreases in extent in the Barents between Svalbard and FJL.  Even though the "cyclone cannon" of 2016 and 2017 has slowed it's rate of fire, what we have now is plenty troublesome.

The counter-flow appears to be across the CAA into the Canadian shield on one side, and across Eastern Siberia on the other.  I anticipate another Arctic break out across the Eastern US, and eastern China and Japan may find themselves unusually chilly as well.

I expect we'll see little to no net increase in extent on either side of the Arctic basin proper, but modest increase in extent in the Baffin and Labrador seas, the Greenland sea (driven mostly by Fram export, and the Sea of Okhotsk.  Unfortunately, none of the increases here will be useful for overall ice health.

While the FDD deficit this year is much less troubling than last, it's still bad.  With the marginal seas still taking such a beating from weather I'm not sure the improvement will really do us much good.

So, how can we explain that the volume drop is decreasing, on August and September? Any negative feedback that you know, that could explain this behavior?
I'll offer three hypotheses, none of which are exclusive.

1) The drop is decreasing because there is an overall decrease in available ice.
2) The new distribution of ice is such that there is less vulnerable volume after the Solstice.
3) Ice preserving feedbacks (increased moisture/cloud cover, snowfall/increased albedo) decrease late season heat uptake.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: January 05, 2018, 05:46:37 AM »
NH snow cover is also interesting right now:

That is very interesting..., and I'm not sure of the correct way to take it.  Is there less humidity all of a sudden?

not less humidity but perhaps more rain instead of snow ?
Exactly my thoughts.  Cover may be down because cover may have been melted.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: December 31, 2017, 09:43:47 PM »
I wonder how that might impact sea ice formation ?

I also wonder what it will mean for precipitation (snow) on the sea ice in the Pacific side of the Arctic? Last year, we saw what the train of Atlantic storms eventually meant for the melting season.
Indeed - that snow provided significant protection for the ice.

I think on the Pacific side, there is a very important difference - That snow is being deposited further south by 5-15 degrees of latitude.  It will start seeing warmer temperatures and significant sunlight earlier in the process and have longer to melt.  It will also have less time to thicken before the net energy balance shifts to where we have little to neutral heat exchange in that part of the Arctic.

Similarly, that snow is landing on ice which formed later, and which now will be further insulated from the remaining cold season.  I'm wondering if we will see large stretches of the Beaufort and Chukchi *starting* the melt season at less than 1.5 M thickness, possibly < 1. 

Time soon to start tracking albedo and estimating heat uptake vs radiative loss.

Put somewhat differently - favorable melt season temperatures and albedo won't be as much help if we start with significantly less ice in the first place.

Arctic sea ice / Re: 2017 sea ice area and extent data
« on: December 31, 2017, 09:08:33 PM »
Wow, the year will end below 12 million km2 for the first time on record:
And that, is now Exhibit "A" for why I didn't vote on the max extent poll.

Arctic sea ice / Re: Arctic Image of the Day
« on: December 17, 2017, 09:07:14 AM »
...looks to me like an old bear dying naturally.
You base you conclusion on what evidence?

Arctic sea ice / Re: JAXA Arctic Sea Ice Extent Ranking - end of 2017
« on: December 17, 2017, 08:52:41 AM »
I'm not even going to hazard a guess. Pure. Dice. Roll.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: December 13, 2017, 08:58:07 PM »
Although two years, statistically, won't determine a new state, it has only gotten 'cold' once in almost two years, according to the DMI 80N graphs.

I wonder what the atmospheric physicists and climate modelers and such have to say about what could steadfastly maintain North Pole winter 'warmth'.
I'll hazard a predictive summary of their comments- warmer water, thinner ice, far greater inputs of moisture from lower latitudes.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: November 08, 2017, 02:58:41 AM »
The post by Numerobis above shows the FDD anomaly, which though high is significantly below 2016. The first image below shows 2017 and 2016 Daily Mean Temperatures North of 80 degree North, so far somewhat colder this year though still well above average.

The second image shows temperature anomalies forecast for the next few days, which indicate the continuation of high positive anomalies on the extreme Atlantic and Pacific sides of the Arctic, as has been the case for some time.

Will this pattern persist and what will be the effect on the where and when of freezing in extent and volume?
I think the pattern will persist as long as we have so much open water in the Beaufort and Chukchi.  They're a powerful heat engine right now dumping energy directly into the Arctic.

The higher FDD's are a relief, but we're still below pretty much everything but 2016-2017.  We have an additional wildcard I'm going to be keen about - snowfall.

All of that open water combined with intrusions of moisture on the Pacific side are bound to increase the snowcover we have over the re-frozen ice.  This is translating into much more snowfall, and each additional inch of snow conservatively has 5+ times the insulative value of ice.  I will be interested in snow depth anomalies as much or more than I'll be interested in FDD's. 

Early deep snowfall has the potential to seriously impede late season thickening of the pack.

Aggregate depths in the past came later in the season and were typically below 40CM:

Arctic sea ice / Re: 2017 sea ice area and extent data
« on: November 08, 2017, 02:16:04 AM »
(Two years to go, but I'm not holding my breath.)
True enough, but I think both 2013 and 2017 started low enough that without cooperation from the weather, it could have happened.

We haven't gotten there, we probably won't, but I still think we've had what could be considered near misses.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 31, 2017, 07:07:56 AM »
trying to model heat flow

That sounds very interesting.

With all this talk of early ice growth trapping summer heat in the water underneath the ice, I've been wondering what data there is on that... and at what depth the water temperature is most relevant for a seasonal ice outlook.

I know ARGO floats have some capability to operate under sea ice and save up the data until it's safe to transmit... but I've never seen any actual data beyond 65N.
Itp 95 hovering around 84nth polewards of svalberd has been showing some regular overturning to below 700m with above the scale temps and salinity rising from deep to replace surface to depth downwelling as the surface cools. This location being well inside the pack, this cannot be good for atlantic side ice formation/survival. Particularly over deep ocean as tis. As of day 304:

They have some new buoys itps 100,101,108 out on the central beaufort. They appear to be showing the halocline stabilising there, after a shaky period before it crusted over, not much salinity differential compared to a decade back.
It is on the Atlantic side that I think most desperately needs instrumentation, to track exactly the kind of overturning and changes in the water column you are mentioning.  While the Bering and increased captured insolation are important to what we see playing out, I think input from warm more saline Atlantic water is really what will tip the balance in the Arctic's heat budget.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 29, 2017, 07:45:56 AM »
Much better depiction of cloud cover to be had here :

Can be broken down into low,middle and high cloud also.
Incredibly useful!  Thanks!

Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 28, 2017, 01:03:26 AM »
trying to model heat flow

That sounds very interesting.

With all this talk of early ice growth trapping summer heat in the water underneath the ice, I've been wondering what data there is on that... and at what depth the water temperature is most relevant for a seasonal ice outlook.

I know ARGO floats have some capability to operate under sea ice and save up the data until it's safe to transmit... but I've never seen any actual data beyond 65N.
Almost by definition there will be guess work involved regarding water temperatures, as once the ice is in place we no longer have satellite data.  For data on temperatures at depth, we're much worse off - but that's exactly one of the factors I need for following what I think is a key metric - total arctic ocean enthalpy.  I'm mulling how to source that, and I think it's key to the refreeze as well.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 28, 2017, 12:42:25 AM »
The farmers almanac has a proprietary method for predicting the weather with good results.

Ok, I'll overlook that, but I agree that we will see rapid recovery of SIE and commensurate trapping of enthalpy in the Arctic Ocean.

SIE *will* appear to recover faster against past years and the average *exactly* because as per the last 10 years, there is far more open water to be covered.

I keep seeing this sort of thing cited as recovery.  It isn't.

Here are the *only* things which I think can be accurately described as Arctic "recovery":

1) Net multiple (at least 3, preferably 5) year over year decreases in Arctic Ocean total enthalpy.
2) Net multiple year over year increases in total Arctic sea ice volume.

That's *it*.

Any other metrics are going to be derivative of and affected by other forces in play which are far more volatile.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 28, 2017, 12:28:47 AM »
Very few of our registrants seem to take any substantive interest in the 2017/18 freezing season, the topic of this forum. Sharing of ungrounded speculation and personal hunches is very boring. Maybe we should just shut it down and come back in May. Visitation levels don't justify the effort.
Please continue.  I apologize for my lack of participation over the last few weeks - personal events have overtaken me (including surgery and full recovery from thereof).  I hope to be back on the saddle shortly.

I've been catching up on your graphing A-Team, and rolling around in my noggin is a notion of trying to model heat flow via a comparison of sea water temperatures, estimates of sea ice and snow thickness, sea surface temperatures and net atmospheric moisture content.

It is ambitious, but I'm going to start looking on in the developers forum for standards, sources and methods to assemble gridded data.

With that, the next set would be to apply various heat flow equations to each of the layers to come up with a composite heat loss number for each grid cell.  I think an average over time is indicated here.

Overall goal is to have that as a tool we can use which would help understand the refreeze dynamics.  Net heat loss I think is key.

Arctic sea ice / Re: Latest PIOMAS update (October, mid month update)
« on: October 27, 2017, 11:44:03 PM »
AGU17 Search “piomas”

GC43J-04 PIOMAS-20C: Variability of Arctic sea ice thickness and volume over the 20th Century.
Axel J B Schweiger UW-APL
C33C-1205 Seasonal evolution of the Arctic marginal ice zone and its power-law obeying floe size distribution
Jinlun Zhang  UW-APL
C21B-1119 Winter Arctic sea ice growth: current variability and projections for the coming decades
Alek Petty
C33B-1201 The Impact of Moisture Intrusions from Lower Latitudes on Arctic Net Surface Radiative Fluxes and Sea Ice Growth in Fall and Winter
Bradley M Hegyi
C21D-1144: Anomalous circulation in the Pacific sector of the Arctic Ocean in July-December 2008
Gleb Panteleev
A series of papers that marvelously quantify what we've been observing the last few years, most dramatically the last 2 1/2 or so.  I look forward to more.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: October 10, 2017, 08:52:00 AM »
That animation is mildly encouraging.
Gonna throw some cold water at you.  The sooner the ice shows up, the sooner it locks accumulated heat in the water.

Arctic sea ice / Re: JAXA 2017 Arctic SIE September daily minimum: June poll
« on: September 24, 2017, 09:58:52 PM »
The JAXA extent minimum for 2017 was 4.47 million km2 on 9 September 2017.  So the correct bin in this poll was 4.25-4.5.

This means that 96.8 percent of the votes in this poll were too low, 2.4% were too high, and 0.8% were in the correct bin.  Moreover, the median of the votes in this poll was about 2.93 million km2, which is 1.54 million km2 too low.

Compare with previous years:

June 2013 poll:  99% of predictions were too low, 0% were too high
June 2014 poll:  98% too low, 0% too high
June 2015 poll:  73% too low, 18% too high
June 2016 poll:  91% too low, 3% too high (JAXA),  and 94% too low, 2% too high (NSIDC)

Thanks for pointing out the obvious. For 5 years in a row now the large majority of posters on this site have been wrong about the ice. This isn't random bias either, as they are always overestimating melt. It's past time for most people here to adjust for their bias and follow the data more closely.

Adjustment needed.  Truedat
Now hang on just a minute.  The June poll is absolutely not intended to be definitive, and for many of us is our best guess based on previous behavior of the system. 

For example, my guess (3.25-3.5 million) was based on the application of a statistical expectation of typical summer melt behavior going back to 1980.  What made my guess wrong was something that hasn't been predictable - peak melt season weather.

I'll also say that my later season estimates have been much closer - even dead on (IJIS extent).

There may be bias, but most of the guesswork being done *is* founded on reasonable expectations.  With the ice in its current state, as it has been since after 2007 and more so after 2012, each season is a dice roll.  If we'd had conditions like 2007 or 2012, no doubt my estimate this year would have been on the *high* side, and we all be talking about how our bias was wrong in the opposite direction.

Arctic sea ice / Re: The 2017/2018 freezing season
« on: September 23, 2017, 03:13:17 AM »
Looking at dmi forecast you can see that the pacific side is still melting a bit, it will take maybe 2-3 weeks before we see big refreezes here.
In my opinion after this year we can see, that very often the effect of open ice in september in many years like last years may have a positive effect of next years ice.
Maybe the water just cools down more if it refreeze later.
So many years with catastrophic ice and regain the next year now.
South of 80N will refreeze more slowly, possibly not refreeze for quite a while.

Not sure if the heat loss will make up for the net increase in enthalpy.

We may see a lot of imported heat from cyclonic storms pulling moisture north from tropical and mid latitutdes.

That will slow heat loss from the Arctic.

Arctic sea ice / Re: The 2017 melting season
« on: September 20, 2017, 06:01:31 AM »
We may simple by in a holding pattern.  The summer minimum in extent may be constrained by the water and air temperatures and circulation.

There could be a 'pause' (dare I use that term?!) in volume loss due to changes in global energy distribution
I think it will transfer, and that's will be what kills the pack.

I think it will take some time - possibly decades as others have suggested.

Even without a sub 1 million KM2 melt year, I think the trend is going to be very bad for life in the northern hemisphere.

I think we are starting to see the wild oscillations in climate that will by typical until the heat redistributes propotionately in the system.

It's not clear to me how the Pacific and Atlantic can both get hotter without that heat transferring to the Arctic, but assuming it can happen, the Antarctic is screwed worse than I thought.

Arctic sea ice / Re: The 2017 melting season
« on: September 18, 2017, 08:52:23 PM »
Probably my final 2017 descent to the min graph update. Probably.
I find it interesting that only 2007, 2011, 2012, 2015 and 2016 are lower, and we are in the "pack" for most of those save 2012.

In volume, we are lower, and in average ice quality, I think we have to go back to 2013 end of season to see anything approaching what we have now - but 2013 still had more thick ice than we have now.

A fascinating year so far, and one which may possibly reflect a new transitional pattern where feedbacks from increased water vapor like cloud cover and increased snowfall attenuate summer extent loss.

I think this will continue for some time, possibly even decades.  I think it will be punctuated at intervals by deeper meltouts to near or under 1M KM2 area, possibly under 1MKM2 extent, but will recover.

I think the transition to fully, seasonally "ice-free" Arctic conditions won't happen until we see water temperatures at depth in the basin rise at least a degree C.  At that point, there will be sufficient energy to continue vigorous bottom melt long enough that even the cloud and snow cover feedbacks won't reduce albedo enough to save the ice.

(Edit) A caveat to the ice's survival is tied to the refreeze rather than the melt season.  With Arctic amplification and the disruption the Hadley/Ferrell/Arctic cell circulation, winter temperatures will be crucial to the ice's survival.  If we start seeing winters which consistently follow 2015/2016 and 2016/2017 temperature pattern, the pack will be come far more vulnerable to factors which previously were marginal, such as Fram export which carries off the remaining thick MYI.  A bad refreeze leaving ice in the state it was this year in May then means that even what was a normal melt season prior to 2007 could become catastrophic.

We are very fortunate I think, that recent melt seasons have been anemic.

Arctic sea ice / Re: IJIS
« on: September 15, 2017, 07:44:55 AM »
This sucks so much!  I, like all on this forum, need ZERO ice!  Those damn denialists have to be proven wrong!  Our earth is going to go ice free and they have to pay!!
Life's hard, but we need to go on in a way or another...
Beyond the absurdity of somehow making denialists pay, I have to say I'd love nothing better than to to have them proved right... but I won't be, nor will the climate cooperate.

What we are seeing is the climate equivalent of a fugue, as we go through a period of chaotic behavior as we transition from year round ice coverage to seasonal coverage.

Arctic sea ice / Re: The 2017 melting season
« on: September 13, 2017, 07:32:06 AM »
Arctic is certainly an eye catcher. So are polar bears, although they have lost their luster as the "canary in the mine" since by all accounts their population is stable and they are not drowning or starving.
<raised eyebrow> 
You may want to defend that statement ... in a different thread.

Arctic sea ice / Re: The 2017 melting season
« on: September 06, 2017, 02:14:12 AM »
no net refreezing growth anywhere

Yes, which is starting to be harder to reconcile with observational products, areas shooting up by some 100k's in a few days and things like that.
... which I think in fact may be related to limitations of those products trying to measure what are threshold conditions in the Arctic.

They were designed to analyze the ice based on a multi-KM grid, and I submit have serious challenges acurately representing the atomized slush we see in the region currently.

I also wonder if they are able to deal accurately with increased snowfall, which is also a new feature of seasonal behavior.  As someone else said in the forums, the Arctic is no longer (or at not completely) a desert.

I think we've already seen a few years of this, with increasing destruction of ice quality starting in 2013 - which was a watershed for quality even as it was a rebound.

We have a fraction of 2012's MYI, which has been distinctly decreasing in thickness as well as area.  We are now moved state in the system behavior where the total effective ice coverage will match very closely the total annual flux in heat entering the region.  It's only by grace of the weather we haven't passed our 1 million KM2 "Ice free" state.

The feedbacks which are preventing that are going, some year, to be overwhelmed, and that sometime is getting very close.

I think Rob Dekker is on to something watching albedo and snowfall.  Unlike the pre-2007 years, I don't think the Arctic has the buffer any more which can soak up excess heat.  We've been steadily losing ground in the refreeze.  Warmer winters are going to end up what kills the Arctic, not summer heat, I think.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 03, 2017, 05:29:55 AM »
Interesting watching the pull-back from Svalbard and the Barentsz.  Perhaps Atlantic water is making itself felt again now that the thickest of the MYI in the area has melted out, and is no longer being replenished from the pack.

If we get cyclones rolling up the coast, it will be interesting to see if the edge retreats back as it did last year, even as the interior froze.

Arctic sea ice / Re: IJIS
« on: September 03, 2017, 05:23:02 AM »
There was a lot of compaction in my view due to the persisting action of an HP on beaufort sea. This is also causing a sisignificant temperature drop though. As usual in this part of the season we're probably having refreezing on the CAB and melting/compaction of peripheral ice. They will tend to offset each other as we move towards the minimum...
To add - there are large areas of thin, highly fractured ice as well, which is vulnerable to bottom melt, even as air temperatures drop.  Until they drop down to -5/10C, that can continue to happen.

Arctic sea ice / Re: The 2017 melting season
« on: August 31, 2017, 03:45:56 AM »
Would not take much for most of the ice in that image to disappear
True, but not much action seen out to day 5 in either of our ice thickness and ice boundary predictions systems, ESRL and Hycom, though note the suggestion of CAA garlic press onset in the latter which could potentially break up what little remains of the very thickest ice.

Indeed very little happened by way of trend in the 13-29 Aug 17 time frame for UH AMSR2 sea ice concentration, which mostly wobbles between dispersion, compaction, and bulk ice pack displacement.
I expect it all got thinner however.

Right now, I'm watching the eastern seaboard of North America as I think the first of what will become a regular series of tropical depressions will start sweeping NE to eventually descend on the Barentsz, taking in train massive amounts of moisture.

At some point, the remains of Harvey will emerge from the Mississippi/Ohio watershed and similarly start a more rapid northeasterly trajectory.

If the Cyclone Cannon starts up, that will push the minimum out, possibly quite a ways, as the heat they carry will slow loss to atmosphere and permit more bottom melt.

If it does not, then we may see an "early" start to the refreeze, which may still be bad news, as it will tend to trap more of this season's heat.

Regardless,  anything beyond 2nd year ice will be at historically low levels, and none of it particularly robust, even as it puts a lid on the arctic.

Arctic sea ice / Re: IJIS
« on: August 26, 2017, 02:07:11 AM »
That seems about right.  If melt picks up then 4th place is likely, otherwise 6th.

I think it is worth noting, that all of the years in question which will likely exceed 2017's melt, have occurred in the last decade.

If this were 2007, everyone would be fairly complete shock over how low extent is, much less volume or area or quality of ice.

Recent years have innured us to just how incredible these seasons are.

Arctic sea ice / Re: IJIS
« on: August 22, 2017, 05:16:42 AM »
Too less of easy ice to melt remain. I don't expect any significan decline further.
Where is the heat?
The main thing of this melting season could be the Arctic SSTs. It's worse than last year and we remember what was the 2016 fall
The effect of insolation on the ice North of 80 is pretty much done, so the end of season story will be whether or not heat loss out of the main pack will be fast enough that it can compensate for bottom melt.

As various images indicate, there is a whole lot of extent which scarcely qualifies as such.  That what is in play.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 18, 2017, 12:54:40 AM »
Crazy fluctuations in CAB area. Last three days: +95k, -117k and now +111k. I will say more about it in a second post. Extent is more reasonable, Greenland Sea drops most with smaller contributions on several fronts.

Update 20170816.

Extent: -82.2 (-45k vs 2016, -210k vs 2015, -697k vs 2014, -619k vs 2013, +721k vs 2012)
Area: +67.5 (+318k vs 2016, +130k vs 2015, -684k vs 2014, -416k vs 2013, +777k vs 2012)

I'm wondering if the fluctuation is a side effect of how granular the pack has become? Is it perhaps tied to the resolution limits of the sensing and computational systems? (E.g 12.5 KM grid)

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 13, 2017, 10:09:38 PM »
Amazing drop in area today, mostly thanks to a regional century drop in the CAB.
Not unexpected, though, as large patches of the ice pack look very iffy.

The region was full of sub-1.75 meter ice.  The bottom melt is now catching up with that.  I expect us to see continuing major SIA losses over the next few weeks for the same reason.

Curiously, because of the highly random distribution of fractured MYI, we may not see the same impact on extent.  We could see much of the basin at very low levels of concentration.

Arctic sea ice / Re: Gulf Stream stall
« on: August 02, 2017, 12:39:36 AM »
I'm still not convinced of the "slowdown" hypothesis.

Annual flow of it into the Arctic is greater that the total winter ice volume by a factor of 20.  I have a hard time believing brine expulsion is the primary driver of that.  Even without that, even at higher temperatures, thermal contraction will provide a huge amount of energy to drive the current.


I think the ice will be more dispersed, which follows the poor quality we have seen.

Much still depends on weather.  I am keen to see what the next storms do, as badly placed, the could radically change the outcome.

Arctic sea ice / Re: IJIS
« on: July 31, 2017, 08:17:49 PM »
IJIS looks stubborn cause I was expecting bigger drops. Thin ice, probably strong storms till the end of melting season. Let's see what will happen
It's turning to slush and spreading out.  Seems to be a side effect of the weak pack we have, as the ice appears to be breaking up into smaller pieces far more readily, which reduces melt ponding.  The cloudiness then prevents sunlight from providing the coup de grace.  So far, it looks like a strong ice supporting feedback mechanism.  However, that storm... we will see how it deals with that.

Arctic sea ice / Re: The 2017 melting season
« on: July 31, 2017, 08:13:05 PM »
20 days in the Beaufort Sea. The area shown is from about 73-77N, 137-157W.

To my eye concentration increases as melt sets in, before catastrophically collapsing
Dovetailing with subgeometer.

This is the Beaufort on the 29th, a still, and shows about a quarter million KM2 of extraordinarily weak ice.  I'm doubting it will survive the coming storms/dipole, which at 72 hours out, the first one looks pretty certain.

Generally when Ice looks like that, I give it about a week before most of it is gone.

Arctic sea ice / Re: The 2017 melting season
« on: July 25, 2017, 05:37:23 PM »
Mostly clear view of the Atlantic side today and wow look at those holes opening up!
Aside from embedded MY I, most of that extent finished the freeze under 1.75M as I recall.  I expected the holes and am glad there aren't more.

More generally, I'm anticipating a reestablishment of the "Atlantic melt front" we've seen from NE Greenland running north of Svalbard and FJL, opening up a couple 100KM into the CAB proper.  I expect all the peripheral seas to melt out almost entirely.  In short, I think the end of the year will see the ice circling the wagons in the CAB at the finish, somewhere close to or slightly below 2007/2011/2016.

Arctic sea ice / Re: Latest PIOMAS update (mid July update)
« on: July 25, 2017, 05:26:00 PM »
What I notice on Wipneus's graph is the September 10 plots used to be (1980 & 90s) consistently above the 0.26m plot <snip>

Disclamer:  Wipneus's graph shows the trends.  Weather will determine the details.  :)
Very much in accord with this.  I think the key here is, unlike measuring area or extent, wip's strategy is actually a proxy for estimated heat uptake.  If I were building and placing buoys, I'd add sensors to measure full spectrum radiation.   There is a *partial proxy for *that* in the form of the voltages coming off of buoy solar arrays, but that's not complete. 

Arctic sea ice / Re: IJIS
« on: July 24, 2017, 08:03:10 AM »
What I've seen is an almost "compressive" feedback behavior, where other forces come into play slowing the melt.

I remember bbr2314 talking this fall and winter about the possible ice-age inducing effects that extra snow would have on the arctic. I dismissed his zeal around the cooling effect it would have - esp. during fall and winter. However, in hindsight the extra snow, and other related negative atmospheric feedbacks, seemed to have slowed melt in 2017 and 2016(more because of clouds, etc).

Have we entered a new phase of the arctic? Cloudy-cool-summers, Stormy-warm-winters. AKA the Wimpy Ice Phase, where sea ice extent hangs on while ice thickness plummets. How long will this phase last?

One thing seems sure to me given the decadal trend of sea ice volume loss, we are rapidly approaching the point when one ice unfriendly winter followed by an ice unfriendly summer will yield a BOE for the Arctic.

In the meantime, perhaps nature might give us a few more years to figure things out before we reach the end of the whip. In other words, ongoing BOEs, a highly-disrupted atmospheric circulation and a planetary energy budget that's running away from us at an unstoppable rate.
Snow cover is a highly volatile and vulnerable negative feedback sadly.  Unlike ice which is realtively durable vs. things like air temperature and rain, snow can vanish in a matter of hours completely changing a major system dynamic (albedo) literally overnight.  As such, it is much more at the mercy of chance, which over the last 5 years following 2012 has managed to work more in our favor.

The energy budget and total enthalpy in the system is The Thing.  In a sort of inverse Pit and the Pendulum, that heat raises the target for each swing of the annual solar "Pendulum".  Eventually, however much the Arctic manage to suck in its belly, it will not be able to avoid getting cut lethally; at least, not without some sort of stupendous intervention.

We're not going to see it coming, as our current metrics like IJIS extent can't "see" that heat, and the nature of the ice and the system are changing in ways that we can't quantify.  Right now, I think anyone making a definitive prediction of the year of the ice's disappearence is throwing darts blindfolded.  We simply don't have all of the data we need to predict that.

Arctic sea ice / Re: IJIS
« on: July 24, 2017, 07:52:32 AM »
My current working hypothesis about this can be summarized thus:  <snip>
Thus, everything points to an Arctic which very suddenly changes -- even if we cannot tell when this will happen.
There is much merit to your observation, Dharma Rupa.  The Arctic has become a very chaotic system, with the potential to tip over into a very different regime very quickly.

I think we need to be tracking other dimensions more closely - sea water heat distribution, albedo, rate of thermal transfer between water and atmosphere, water vapor, total system enthalpy among others - as I think they would give us more insight.  It would be better if we had history for all of those things, but sadly, we do not.  If wishes were horses, beggars would ride.

Arctic sea ice / Re: IJIS
« on: July 23, 2017, 07:17:16 PM »
The mistake you and others make is the assumption that this year's ice is anything like previous years.  Or that this year's climate is anything like previous years.   Or that atmospheric circulation or ocean currents and temperatures are anything like previous years.

You can crunch numbers all you want, but if circumstances in the past in no way resemble current circumstances, then it's just GIGO.

You can't treat a transforming system as if it's a static one and derive anything useful.

We have variations on this post LITERALLY EVERY YEAR.  One year they will be right, much like a stopped clock. When that year comes, don't delude yourself that you deserve credit for your foresight.
To underscore Peter's point, I've made similar assertions, presented similar tables of data, made similar dire observations about the ice, only to have it act inconsistent with my predictions.

In short, in spite of the state of the ice, in spite of previous years behavior, because of the state changes taking place in the system at this level of coverage and volume, those statistical analyses lose their predictive power.  What I've seen is an almost "compressive" feedback behavior, where other forces come into play slowing the melt.

My current working hypothesis about this can be summarized thus:  once melt retreats past about 75N over all, the system dynanimics change sharply. My thought is, that open water becomes a buffer which more efficiently and evenly redistributes heat.  I think the dynamics of phase change come into play as well, with heat which previously melted ice, taken up by evaporation, which in turn further contributes to increased albedo.  To summarize, we see increasing feedbacks from different mechanisms that don't exist or are retarded at higher levels of ice coverage.  I think they are the only reason we aren't seeing open water at 90N by early August.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: July 23, 2017, 01:50:16 AM »
The ice in Kara shows how fast it can disappear suddenly.
The ice generally really is following my expectations.

Arctic sea ice / Re: The 2017 melting season
« on: July 21, 2017, 09:20:20 PM »
<snip: Too many nested OT comments. Leaving your relevant notice intact. JP>

Back to topic please.  Discussion of the relative accuracy and merit of various organizations data belong elsewhere on the forums.  Ad hominem attacks belong nowhere in our discussions.

Arctic sea ice / Re: The 2017 melting season
« on: July 21, 2017, 05:05:55 PM »
I agree with 2015 and 2016, not so much with 2013, at least not on the base of a single image.

Here's a second image, showing some open holes on July 6th 2013:
2013 was terrifying. Cloudy weather and calm conditions are the only reasons we didn't have a crash that year.

Arctic sea ice / Re: The 2017 melting season
« on: July 19, 2017, 09:33:34 PM »

Conventional wisdom tells us that years with high compactness ratios generally don't break records. At some point conventional wisdom no longer applies. We don't know if that point has been reached this year. Doesn't look like it to me, but you never know (volume is still record low, according to PIOMAS).

The current weather forecast is perfect for ice retention. Conventional wisdom says that at some point this will cause hiccups in extent decrease. Greenland surface melt may show a spike though:

It is hopeful that the weather is good for retention.  OTOH, pertinent to our understanding of compactness,  what's N and E of Svalbard I think contributes significantly to that high ratio, and isn't exactly reassuring, considering the image I captured below.

I will add, that recent changes and melting out in the Barents are starting to show a return to both higher SST's, and a reassertion of the "Atlantic Front" we saw last year.  The second image shows how a combination of drift and warmer Atlantic from the south has started opening up the water north of Svalbard as we have seen frequently over the last few years.

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