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magnamentis

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Re: The 2016 melting season
« Reply #3250 on: July 12, 2016, 07:08:36 PM »
Melting momentum is really low according to Dr. Schröder's melt pond fraction simulation:

i think this is because there are many more smaller pieces between which the water that would usually
be kept as melt ponds drains to the ocean underneath.

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Re: The 2016 melting season
« Reply #3251 on: July 12, 2016, 07:18:25 PM »
I believe the model is entirely based on weather conditions, so that can't be the reason for a small melt pond fraction during June (never mind the fact that the pack was less broken up than it is now).
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Richard Rathbone

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Re: The 2016 melting season
« Reply #3252 on: July 12, 2016, 07:55:35 PM »
I thought that. Then I checked how long ice lasted in the Hudson in the past few years. The model has it right. There is a non-zero chance of ice into September there.

The methodology was presented (poster) at AGU 2013 and its beaten every other method in SIPN over the past three years for predicting minimum extent from 50 days out. Predicting what it will say in 3 weeks time is fairly dodgy, but what it says the minimum will be once we get to August is not worth betting against.

Richard - I am not aware of _any_ sea ice surviving in the main Hudson Bay over the past 30 years. Are you possibly mixing this up with the Foxe Basin?

Wipneus's home brew extent for the Hudson Bay region was non-zero last year. It goes eventually, but there's still there at the end of August. Over the next week you'll likely see the Slater probabilities tumble in Hudson Bay as the forecast date moves into September, but as of today, its quite reasonable to expect a bit of ice still in the Hudson Bay in 50 days time.

seaicesailor

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Re: The 2016 melting season
« Reply #3253 on: July 12, 2016, 08:09:45 PM »
I believe the model is entirely based on weather conditions, so that can't be the reason for a small melt pond fraction during June (never mind the fact that the pack was less broken up than it is now).

I am not sold to this model. Why that big difference in the CAB precisely in a location where the final extent in 2012 was not so distinguised? Why all that white in Beaufort and Chukchi? I never get it.
Among other things, it has had a tendency to overestimate ice extent in September (CPOM in the graph)
« Last Edit: July 12, 2016, 08:22:25 PM by seaicesailor »

Tigertown

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Re: The 2016 melting season
« Reply #3254 on: July 12, 2016, 08:19:30 PM »
recall that area of warm water at the Siberian Islands:
compare July 8 with July 12


plinius

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Re: The 2016 melting season
« Reply #3255 on: July 12, 2016, 08:22:22 PM »
Wipneus's home brew extent for the Hudson Bay region was non-zero last year. It goes eventually, but there's still there at the end of August. Over the next week you'll likely see the Slater probabilities tumble in Hudson Bay as the forecast date moves into September, but as of today, its quite reasonable to expect a bit of ice still in the Hudson Bay in 50 days time.

Richard - a) false assertion that there was ice last year in Hudson. Look here
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20150805.jpg
The ice disappeared in the first week of August. Completely.
b) You missed that typical region statistics, like cryosphere and Wipneus' analysis add other regions to the greater Hudson area. This includes Foxe Basin, which is not what we are discussing here, and which is also officially not part of Hudson Bay.

And no - it is fully unreasonable to expect any significant ice in Hudson Bay for end of August. Happy to offer you a 5:1 bet, which is double the quote that Slater's model would take for that bunch of ice in the southern part.

Neven

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Re: The 2016 melting season
« Reply #3256 on: July 12, 2016, 08:34:44 PM »
I am not sold to this model. Why that big difference in the CAB precisely in a location where the final extent in 2012 was not so distinguised?

Mind you, below the image it says in the blog post:

Caveat: This is a model result, and so the distribution of melt ponds doesn't necessarily reflect reality.

Quote
Among other things, it has had a tendency to overestimate ice extent in September (CPOM in the graph)

I believe Schröder only started to participate in the SIPN SIOs last year. I don't know what the CPOM predictions before that were based on.
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S.Pansa

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Re: The 2016 melting season
« Reply #3257 on: July 12, 2016, 08:41:51 PM »
Wipneus's home brew extent for the Hudson Bay region was non-zero last year. It goes eventually, but there's still there at the end of August. Over the next week you'll likely see the Slater probabilities tumble in Hudson Bay as the forecast date moves into September, but as of today, its quite reasonable to expect a bit of ice still in the Hudson Bay in 50 days time.

Richard - a) false assertion that there was ice last year in Hudson. Look here
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20150805.jpg
The ice disappeared in the first week of August. Completely.
b) You missed that typical region statistics, like cryosphere and Wipneus' analysis add other regions to the greater Hudson area. This includes Foxe Basin, which is not what we are discussing here, and which is also officially not part of Hudson Bay.

And no - it is fully unreasonable to expect any significant ice in Hudson Bay for end of August. Happy to offer you a 5:1 bet, which is double the quote that Slater's model would take for that bunch of ice in the southern part.
And you perhaps missed what Slater's extent probability plot is acutally showing. To quote Dr. Slater himself:
Quote
Remember that there is no single correct answer; colors show expected probabilities only. One way to think about the plot is that for the area that shows 80% probability of being ice covered on the forecast date, 20% of that area is expected to be ice free. Do not mistake the blue colored areas as being a simplified extent forecast.

The projected probabilities can also contain error. For example, in August and September, the projections are overconfident at the mid-range probability levels. In hindcast simulations (2005-2011), where the projections expected there to be ice 50% of the time, ice was only present 40% of the time; that's a non-trivial error. Reliability is computed for days within a given month over the whole period indicated (2005-2012); individual days may do better or worse. Some months do better than others.

But why have a closer look when bitching about is so much easier ... on the other hand. What is the chance that plinius could have missed something? I am sure it is less then 0,001% (Edit: The chance that I have missed something is of course nearly 100%  8)). 

It seems that the heat has missed the Artic this summer and has gone straight into this melting thread ;D
« Last Edit: July 12, 2016, 08:49:23 PM by S.Pansa »

seaicesailor

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Re: The 2016 melting season
« Reply #3258 on: July 12, 2016, 08:56:48 PM »
https://www.arcus.org/sipn/sea-ice-outlook/2014/august
They predicted above 2013. Then 2015 above 2014 and now 2016 above 2015. At this rate Arctic would be fully recovered. They nailed it in 2013 though (no wonder, it was cold and then cold with some brief heat breaks). So if this year stays as 2013, then 2016 will end up in 5 million km2 (the SSTs and NH heat in general say otherwise but who knows)
It is like they consider sort of weather snapshots, May was warmer? there goes half a million less. June cooler hey put 1 million more.
Slater may be not that correct regionally but ice concentration tendencies already include melt ponds, ice conditions, melting in polynya...
Rob Dekker does not predict regionally but adds on top land snow anomaly which is a cause, if not the cause, of Arctic amplification.
Sorry but every year I contemplate these maps a bit lost in perplexity. I dont doubt they have a scientific value.
Edit: regardless of my rant, thanks for bringing this information to us, Neven and for your blog post
« Last Edit: July 12, 2016, 09:07:58 PM by seaicesailor »

Neven

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Re: The 2016 melting season
« Reply #3259 on: July 12, 2016, 09:34:15 PM »
I just see the model results as an indicator of melting momentum, not as the Holy Grail per se. I believe that - all circumstances, especially volume, being equal - melting momentum tells us a lot about the (im)possible. Last year was interesting in this respect, because an extremely hot July made up quite a bit for the lack of melting momentum. Maybe this year's spectacular start (after a very mild winter) may prove to be another factor to overcome the same lack of melting momentum.

Imagine a year with such a spectacular start, then a decent build-up of melting momentum, interspersed with a couple of periods of divergence and then a very hot July and stormy August. That could well be the first ice-free year.
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jai mitchell

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Re: The 2016 melting season
« Reply #3260 on: July 12, 2016, 09:52:18 PM »
Maybe this year's spectacular start (after a very mild winter) may prove to be another factor to overcome the same lack of melting momentum.

Imagine a year with such a spectacular start, then a decent build-up of melting momentum, interspersed with a couple of periods of divergence and then a very hot July and stormy August. That could well be the first ice-free year.

Perhaps I am not really up on your term "melting momentum"  it seems to me that previous melt rates can easily be overcome by regional conditions.  For example, your most recent blog talks about the very low compaction in the arctic at this time.  It seems to me that a strong compaction event followed by 2 weeks of clear sky would produce all of the 'momentum' you would need for a new low. 

Another idea:  is it possible that the higher rate of fracture (smaller average floe size) contributes to reduced melt-pond size/persistence leading to significantly reduced melt pond area?
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Richard Rathbone

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Re: The 2016 melting season
« Reply #3261 on: July 12, 2016, 10:53:15 PM »
Wipneus's home brew extent for the Hudson Bay region was non-zero last year. It goes eventually, but there's still there at the end of August. Over the next week you'll likely see the Slater probabilities tumble in Hudson Bay as the forecast date moves into September, but as of today, its quite reasonable to expect a bit of ice still in the Hudson Bay in 50 days time.

Richard - a) false assertion that there was ice last year in Hudson. Look here
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20150805.jpg


The ice disappeared in the first week of August. Completely.
b) You missed that typical region statistics, like cryosphere and Wipneus' analysis add other regions to the greater Hudson area. This includes Foxe Basin, which is not what we are discussing here, and which is also officially not part of Hudson Bay.

And no - it is fully unreasonable to expect any significant ice in Hudson Bay for end of August. Happy to offer you a 5:1 bet, which is double the quote that Slater's model would take for that bunch of ice in the southern part.

The Sept 1st archive on Neven's graphs page shows ice in the southern part of the Hudson in 2015 (and several other years).

Neven

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Re: The 2016 melting season
« Reply #3262 on: July 12, 2016, 11:21:03 PM »

Perhaps I am not really up on your term "melting momentum"  it seems to me that previous melt rates can easily be overcome by regional conditions.  For example, your most recent blog talks about the very low compaction in the arctic at this time.  It seems to me that a strong compaction event followed by 2 weeks of clear sky would produce all of the 'momentum' you would need for a new low. 

First of all, a strong compaction event would already entail clear skies. There I saved you two weeks. ;-)

I think the timing of build-up is also important. If it builds up too late, a lot of the ice (inner core of ice pack, not periphery) will still be there when the freezing season starts. Melting momentum is simply something that prevents extent/area decrease from stalling abruptly when weather conditions switch.

Quote
Another idea:  is it possible that the higher rate of fracture (smaller average floe size) contributes to reduced melt-pond size/persistence leading to significantly reduced melt pond area?

It depends on the size of the floe, I guess. What we consider small floes watching satellite images can actually span many miles. In fact, the transition from multi-year to first-year ice has caused much more widespread melt ponding, because first-year ice is much flatter than MYI, I believe.

And a highly dispersed, broken up pack can also soak up a lot of solar radiation. But the solar radiation would have to be there, of course. And that's the point with this melting season: things have been too cloudy during this crucial period, and still are, so not enough solar radiation has been absorbed to sustain high melting rates in July and August (which is what we are seeing already on some graphs). I'm not sure if the mild winter, the spectacular start to the melting season and relatively high SSTs can compensate for that, especially given the fact that volume/thickness isn't significantly lower in the places that matter, than it was during years when this kind of weather conditions put a stop to everything (2010, 2011, for instance).

I know, boring. But that's what I think the data is saying. There is no data on everything (ocean heat flux in particular), so that leaves the door slightly ajar.
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Paladiea

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Re: The 2016 melting season
« Reply #3263 on: July 12, 2016, 11:23:30 PM »
Quote
I'm not sure if the mild winter, the spectacular start to the melting season and relatively high SSTs can compensate for that

Heat is heat. As long as there is a mechanism to get the heat to the ice, then it doesn't matter the source.
The most enjoyable way to think about heat transfer through radiation is to picture a Star Wars laser battle, where every atom and molecule is constantly firing at every other atom and molecule.

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Re: The 2016 melting season
« Reply #3264 on: July 12, 2016, 11:30:20 PM »
Quote
I'm not sure if the mild winter, the spectacular start to the melting season and relatively high SSTs can compensate for that

Heat is heat. As long as there is a mechanism to get the heat to the ice, then it doesn't matter the source.

The best mechanism to get heat to the ice is solar radiation, in the short term. Especially if it's helped by melt ponds and open water within the pack.

The best mechanism is out of play this melting season. Make of that what you will.
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Paladiea

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Re: The 2016 melting season
« Reply #3265 on: July 12, 2016, 11:34:10 PM »
Most efficient, I would definitely agree.

But what level of efficiency is required to melt the ice remains to be seen. :)
The most enjoyable way to think about heat transfer through radiation is to picture a Star Wars laser battle, where every atom and molecule is constantly firing at every other atom and molecule.

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Re: The 2016 melting season
« Reply #3266 on: July 13, 2016, 12:08:55 AM »
There will be a year when low efficiency will be sufficient, but I don't think this is the year.  ;)
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Paladiea

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Re: The 2016 melting season
« Reply #3267 on: July 13, 2016, 12:13:04 AM »
As a counterpoint, 2012 depended on a very low efficiency mechanism to achieve its record.  ;D
« Last Edit: July 13, 2016, 12:46:39 AM by Paladiea »
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Re: The 2016 melting season
« Reply #3268 on: July 13, 2016, 01:02:51 AM »
You can go broke in the export business if you are too slow.
18 days

seaicesailor

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Re: The 2016 melting season
« Reply #3269 on: July 13, 2016, 01:20:24 AM »
recall that area of warm water at the Siberian Islands:
compare July 8 with July 12


May give a bad surprise for the ice in the coming weeks

plinius

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Re: The 2016 melting season
« Reply #3270 on: July 13, 2016, 01:56:02 AM »
@Pansa: Really? Do you think you enrich the discussion by explaining to me what a probability is? And what I can see is that the questioned model predicts 40% survival probability in regions that have close to 0%. So something is going wrong. Perhaps you find something constructive, then we can talk.

@Rathbone: It's part of good conduct to back your claim with a link so that your discussion partner does not have to search. Yet, I found the map you seem to allude to (which is not Neven's, but the AMSR evaluation by Uni Bremen). Very simple - those maps show no ice in Hudson either. In case you got mistaken by the couple of smudges on the map - that's weather. Bremen maps sometimes have spurious ice detections, frequently in shallow waters (I hope you don't think that the ice they show in the north atlantic or also baltic sea is real...). You can easily cross-check by comparing different dates - if a patch of ice does not show up in two subsequent maps, it'll be an artifact.

JimboOmega

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Re: The 2016 melting season
« Reply #3271 on: July 13, 2016, 02:50:41 AM »
The best mechanism to get heat to the ice is solar radiation, in the short term. Especially if it's helped by melt ponds and open water within the pack.

The best mechanism is out of play this melting season. Make of that what you will.

Out of play? I was under the impression that albedo-anomaly accumulated solar energy was higher than ever before.

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Re: The 2016 melting season
« Reply #3272 on: July 13, 2016, 03:12:54 AM »
When I first de-lurked in May, I asked about the ideal set-up for a new record melt. The wisdom was that the set-up was pretty good but late June/early July were critical --- peak Sun after all. This year got a reprieve.  Secondary was strong export through the Fram, or maybe even more important. Why melt the ice in-situ if you can export it? I've been greatly puzzled by those who pooh-pooh export, especially when they say it's not "necessary". Just can't make sense of "necessary". Necessary for what? Seems to me that an added mechanism to remove ice, especially one that doesn't consume resident heat will remain a major factor in the state of the Arctic in Sep.

Question. I've skimmed a few papers on Fram export, and it's deepened my confusion (so that's progress of a sorts). Is there a chart of monthly export that is somewhat current? Thanks in advance.

plinius

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Re: The 2016 melting season
« Reply #3273 on: July 13, 2016, 03:17:37 AM »
Out of play? I was under the impression that albedo-anomaly accumulated solar energy was higher than ever before.

Maybe, maybe not. I thin that statistics do not figure in the snow area, which has fluctuations at least the same size as arctic sea ice. Also the amount of heat sounds large, but I would doubt that it makes heat transfer fluctuations insignificant.
And possibly most important point: You have to get the heat to the central pack, and as interesting as tealight's statistics might be, they do not bridge the gap to cross from getting your bit of extra heat from say the sea of Ochotsk to the CAB... similarly - a little open patch in the Beaufort might still not kill the ice near the pole.

Tigertown

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Re: The 2016 melting season
« Reply #3274 on: July 13, 2016, 05:50:49 AM »
Big drop today. Doesn't mean much by itself, but if it becomes a trend, look out!

P.S. Didn't know CR had this.
Note the big area that looks like a holiday between the Beaufort and the North Pole:
Apparently the area has 25% thickness +/-
« Last Edit: July 13, 2016, 06:13:14 AM by Tigertown »

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Re: The 2016 melting season
« Reply #3275 on: July 13, 2016, 06:29:18 AM »
The Beaufort did this, I believe.Warm water that makes it out that far would not show up on a SST map because the energy would be consumed melting ice. I had to go back a while to get good view of this. I did not how accurate the CR image was. I guess I probably saw it but then it got cloudy and did not realize how bad the spot had gotten. If it gives in the near future, things will really get opened up.
Note the 800N line in the center of pic on first and far left on second one


« Last Edit: July 13, 2016, 07:00:16 AM by Tigertown »

Tigertown

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Re: The 2016 melting season
« Reply #3276 on: July 13, 2016, 07:15:51 AM »
Follow up. Not saying the insolation in the open waters didn't do most of the heavy lifting,but adding the influence of the Mackenzie River makes for a one-two knockout punch with land temps being as they are.
 A 2008 image of the river's plume and another image with bold arrows where currents are. I did not compare 2008 to present land temps(project for someone later maybe).


6roucho

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Re: The 2016 melting season
« Reply #3277 on: July 13, 2016, 07:39:09 AM »
As a counterpoint, 2012 depended on a very low efficiency mechanism to achieve its record.  ;D
Low efficiency but high energy: 6.0 x 10^14 Watts for a typical hurricane according to NOAH's Hurricane Research Division. That number's a proxy obtained by measuring the total amount of energy released by the condensation of water droplets.

"This is equivalent to 200 times the world-wide electrical generating capacity."

http://www.aoml.noaa.gov/hrd/tcfaq/D7.html


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Re: The 2016 melting season
« Reply #3278 on: July 13, 2016, 08:16:12 AM »
After reading the entire thread and reviewing every bit of data posted here, - I'm afraid Bbr may be more than just an alarmist. It seems most people keep gravitating towards a handful of old-school models, focusing their full attention on ice and weather conditions in the region ONLY. Would you want a doctor to only focus on your sore throat when you are sick and running a high fever? The analogy may not be perfect, but the point should be clear enough.

Has anyone actually been looking into air and sea surface temperature trends below 80°N and closer to 60°N? The entire region (Alaska, Northern Canada, Northern Russia) is basically a ring of fire compared to previous years. Some of this heat sooner or later finds its way above 80°N both above and below the ice.

Do we have any data on changes in air/water content due to changes in the biosphere (oxygen and methane levels, salinity, SO4, SO2, H2S, CO2), human activities etc? And how these changes would affect the existing models (pink algae anyone?)

How many feedback loops are at play?

   

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Re: The 2016 melting season
« Reply #3279 on: July 13, 2016, 09:07:34 AM »
That's all true, and there might be a phase change, as Professor Wadhams has argued, but we have no way of predicting the timing of such an event. One day soon the ice might split apart, and be melted in the warm waters of the north Atlantic, and no one here will deny that's happening. In the meantime, people will continue to observe the real state of the ice.

I think people's main argument with Bbr is about what the real state of the ice is, and Bbr's specific predictions of what will happen this year.
« Last Edit: July 13, 2016, 11:40:41 AM by 6roucho »

seaicesailor

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Re: The 2016 melting season
« Reply #3280 on: July 13, 2016, 09:16:34 AM »
Big drop today. Doesn't mean much by itself, but if it becomes a trend, look out!

P.S. Didn't know CR had this.
Note the big area that looks like a holiday between the Beaufort and the North Pole:
Apparently the area has 25% thickness +/-

I'd say these areas are close to 2015F buoy but have to confirm later.
BTW when you write CR for a sec I thought you referred to Cristiano Ronaldo. Second thought was Chris Reynolds :)

Jim Hunt

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Re: The 2016 melting season
« Reply #3281 on: July 13, 2016, 10:43:39 AM »
Note the big area that looks like a holiday between the Beaufort and the North Pole:
Apparently the area has 25% thickness +/-

The Beaufort did this, I believe.

Please do me a favour. Show me on MODIS "the big area... between the Beaufort and the North Pole" that "has 25% thickness +/-". I presume you meant 25% concentration?

If it's too cloudy for your taste show me on SAR instead. Perhaps the Canadian Ice Service can help you?

http://iceweb1.cis.ec.gc.ca/Prod/page2.xhtml?CanID=10062&lang=en

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Richard Rathbone

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Re: The 2016 melting season
« Reply #3282 on: July 13, 2016, 12:20:31 PM »
@Pansa: Really? Do you think you enrich the discussion by explaining to me what a probability is? And what I can see is that the questioned model predicts 40% survival probability in regions that have close to 0%. So something is going wrong. Perhaps you find something constructive, then we can talk.

@Rathbone: It's part of good conduct to back your claim with a link so that your discussion partner does not have to search. Yet, I found the map you seem to allude to (which is not Neven's, but the AMSR evaluation by Uni Bremen). Very simple - those maps show no ice in Hudson either. In case you got mistaken by the couple of smudges on the map - that's weather. Bremen maps sometimes have spurious ice detections, frequently in shallow waters (I hope you don't think that the ice they show in the north atlantic or also baltic sea is real...). You can easily cross-check by comparing different dates - if a patch of ice does not show up in two subsequent maps, it'll be an artifact.

So what? The question for Slater's method is whether satellite microwave measurement shows there is extent in September in the Hudson. It does. It might be weather, it might be low concentration rubble, but that's irrelevant, he's predicting what the measured extent will be and thee is measured extent in the Hudson in September.

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Re: The 2016 melting season
« Reply #3283 on: July 13, 2016, 01:09:39 PM »
Andrew Slater's method of calculating survival probabilities over all the ice, area by area, is invaluable in my view for predicting area, extent and volume at the end of the melt season.

  Global discussions of weather, melt momentum etc. can only get one so far. In the final analysis, it needs to be pointed out where the ice is likely to survive and where it isn't.

  In the spirit of AS, but without detailed modelling, I would suggest that the ice in the Arctic Basin can be roughly divided into 6 regions of melt vulnerability, as shown in the accompanying figure.

  Only in the region next to the Canadian Arctic coast is the ice likely to survive, in my view. For the sake of argument I roughly demarcated a region where all the ice has a probability greater than 80% of surviving the melt season.

  Observe that this region is relatively small - eyeballing, I would say around 2.0 million square kilometres.

  That is essentially the basis for my continued predictions of record low area, extent and volume this year, below the 2012 values, even as June 2016 did not much impress most as conducive to records.

  I invite people to discuss the plot and point out where they disagree with the analysis. As a question: where, outside the demarcated region, do you yourself assess a greater than 80% chance of the ice surviving? How big then is the total such region as you assess it?

iceman

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Re: The 2016 melting season
« Reply #3284 on: July 13, 2016, 01:12:30 PM »
  ....
- There appears to be about 70% chance that a large chunk of ice in the ESS may be cut off from the main pack
  ....

Curious, that's about the same location as the large detachment following the 2012 cyclone.
But the forecast for the coming week shows snow and cooler temperatures between there and the pole, which would seem to diminish the odds.

jplotinus

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Re: The 2016 melting season
« Reply #3285 on: July 13, 2016, 01:34:25 PM »
Slow wing

At first glance, I can only quibble with Laptev portion of your Siberian area. Laptev ice has been stubborn this year. At September minimum, there could well be a 200k extent remnant there.

slow wing

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Re: The 2016 melting season
« Reply #3286 on: July 13, 2016, 02:01:52 PM »
Thanks for the feedback. Yes, I agree - the Laptev is the region I am most uncertain about.

Tigertown

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Re: The 2016 melting season
« Reply #3287 on: July 13, 2016, 02:19:21 PM »
Note the big area that looks like a holiday between the Beaufort and the North Pole:
Apparently the area has 25% thickness +/-

The Beaufort did this, I believe.

Please do me a favour. Show me on MODIS "the big area... between the Beaufort and the North Pole" that "has 25% thickness +/-". I presume you meant 25% concentration?

If it's too cloudy for your taste show me on SAR instead. Perhaps the Canadian Ice Service can help you?

http://iceweb1.cis.ec.gc.ca/Prod/page2.xhtml?CanID=10062&lang=en
I will let you do that if you wish to. It is just a working theory that I have that the area there is getting damaged heavily right under our noses. I am more than content to wait a couple of weeks to see if I am right or not. My ego is not all blown up believing that I am right and am infallible, so if wrong I don't have far to fall.

Archimid

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Re: The 2016 melting season
« Reply #3288 on: July 13, 2016, 02:32:22 PM »
I think Siberian Heat might be counter acted by ice coming from the CAB piling up over that corner. The rest of the periphery will be gone because of Chukchi SST's.

I think that the survival of the >80%  chunk depends on the weather holding that High pressure ridge right along the Atlantic islands. If that changes ice export from the CAB to the Atlantic could make bbr2314's   Arctic in half a reality.

 
 
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

S.Pansa

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Re: The 2016 melting season
« Reply #3289 on: July 13, 2016, 02:56:22 PM »
@Pansa: Really?  Perhaps you find something constructive, then we can talk.

For sure - as soon as your criticism of the model has some substance. I just don't think it has.

A) As you can see (ok, direct link does not work - you can find it under model performance), Slater's model has shown some pretty good skills in predicting the September Mean Extent for the last 3 years.
1) That seems to be the strength of the model - it has done quite well compared to others.
2) And "Mean Sea Ice Extent" was what people were talking/arguing about ( Reply #3223,  Reply #3235)
B) Then you started to argue about the "strange" Sea Ice Extent Distribution shown in the model, especially in the Hudson.
C) But Sea Ice Extent Distribution is not necessarily a strength of the model. At least that is how I read the paragraph I have cited above. Furthermore I can't see that anyone hast claimed it is.

As far as I can remember, the model has shown some "odd" concentration distributions in the past. But that demonstrably (see A above) has not hindered it to predict the September Mean Extent quite accurately.

So does your reservation about the Sea Ice Extent Distribution in the Hudson really cast doubt on the models capacity to predict the September Mean Extent (as you were looking for some verification)?
I don't think it does. At least the results of the last three years - the timeframe in which we can compare model output and reality - do not support this idea, as it has been one of the best models out there.

If Slaters Model is way off this time wrt to Mean Sea Ice Extent & it shows a huge chunk of ice in the Hudson (where there is none), well then you would have a point. But as we have July ... let's enjoy summer first.

PS: Or to put it simple: Can you show us that Slater's Mean Extent prediction is crap based on the fact that his model predicts some areas to have 20% sea ice concentration in the Hudson by August, 29th?
« Last Edit: July 13, 2016, 03:56:36 PM by S.Pansa »

magnamentis

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Re: The 2016 melting season
« Reply #3290 on: July 13, 2016, 03:30:21 PM »
There will be a year when low efficiency will be sufficient, but I don't think this is the year.  ;)

that's exactly the question behind the ongoing discussion as to how this year will further develop. i think you're right, weather still matters this year but less, means bad melt weather is not as abad as it was 5-10 years ago, else we would probably be far away from 2012 by now.

reading through your various posts i take it you did not buy my theory about melt ponds frequently emptying thorough fissues due to the less solid ice in general? i refer to melt ponds mentioned as above, some say there are less ponds and i say there are more ponds building but discharged frequently because the ice is more leaky and permeable than it once was, mostly due to poor freezing conditions = thinner and wamer ice.

Shared Humanity

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Re: The 2016 melting season
« Reply #3291 on: July 13, 2016, 03:40:47 PM »
With my pencil calculations, I seem to have arrived at the conclusion that a 20% chance of ice in the Hudson in September means that there is an 80% chance that there will be know ice. So the model seems to suggest that there will likely be no ice. Seems the model agrees with my thinking and the pencil calculations.

Maybe I'm doing the maths wrong. Where's that damn calculator!


Jim Hunt

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Re: The 2016 melting season
« Reply #3292 on: July 13, 2016, 04:03:46 PM »
I will let you do that if you wish to.

I've already done it. However I thought you might find it educational to try the same exercise before relying on CCI/GFS in future?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Shared Humanity

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Re: The 2016 melting season
« Reply #3293 on: July 13, 2016, 04:06:55 PM »
I will let you do that if you wish to.

I've already done it. However I thought you might find it educational to try the same exercise before relying on CCI/GFS in future?

The concentration in those posted images appear to be about 95% give or take a couple of percent.

plinius

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Re: The 2016 melting season
« Reply #3294 on: July 13, 2016, 05:50:09 PM »
So what? The question for Slater's method is whether satellite microwave measurement shows there is extent in September in the Hudson. It does. It might be weather, it might be low concentration rubble, but that's irrelevant, he's predicting what the measured extent will be and thee is measured extent in the Hudson in September.

I would call that an interesting fantasy. The method specifies which pieces of ice are likely to survive and where. It is simply wrong for Hudson. You can of course dream of ice-slush somehow magically hidden under the surface, but I wouldn't call that connected to reality. I am also not judging his method for the CAB - difficult to do, but given that Hudson is just plain wrong, there is likely some important ingredient missing.

Tealight

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Re: The 2016 melting season
« Reply #3295 on: July 13, 2016, 06:23:41 PM »
PS: Or to put it simple: Can you show us that Slater's Mean Extent prediction is crap based on the fact that his model predicts some areas to have 20% sea ice concentration in the Hudson by August, 29th?

I can show you why slaters model is so off in Hudson, but that doesn't prove that his entire model is crap. His predicted area in Hudson is quite small after all.

The predicted remaining ice in Hudson is at about 55N, which is way outside the arctic circle. Therefore the summer/warming time lasts much longer. At the end of August daily insolation is over twice as much as in the high arctic where ice melt slows down significantly.

Looking back at previous years all ice in Hudson is gone by mid August.
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0813
« Last Edit: July 13, 2016, 07:57:11 PM by Tealight »

6roucho

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Re: The 2016 melting season
« Reply #3296 on: July 13, 2016, 07:18:45 PM »
So Slater's model doesn't take into account variation by latitude and thus insolation? That suggests it can't be used to make regional forecasts at all.

Tealight

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Re: The 2016 melting season
« Reply #3297 on: July 13, 2016, 08:26:17 PM »
Yes Slater doesn't consider insolation, because his model is a statistical model based on regression. He mentions this on his SIPN report and on his website with the most up to date data.

Quote
These are probabilistic projections of sea ice extent. I use a very simple regression/projection method based on prior years and assimilation of the latest data - it's not the most sophisticated method but it does have a fair degree of skill.
Website:
http://cires1.colorado.edu/~aslater/SEAICE/about.html

SIPN report:
https://www.arcus.org/files/sio/25659/sio-2016-june_slater-persistence_0.pdf

In my opinion regional forecasts more than 14 days ahead are unreliable anyway because winds can push ice a few kilometers a day and change the distribution significantly.

TerryM

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Re: The 2016 melting season
« Reply #3298 on: July 13, 2016, 10:07:21 PM »
"Only James Bay, the southern two thirds of Hudson Bay, and the Labrador Sea always clear completely of ice"

http://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=4B35305B-1&offset=2&toc=show

I'd assume that any model that placed ice where it can't be has a serious problem. I've sent photos of palm trees and people lounging on the beach at Port Dover when various models have shown lake Erie to be awash with ice. These models also have problems.

Terry

Nick_Naylor

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Re: The 2016 melting season
« Reply #3299 on: July 13, 2016, 11:15:58 PM »
Or, to put it another way, any model that places ice where it can't be has a serious opportunity.

Slater's model has done a good job of projecting a single number - by chance it happens to be the one number everyone on this board is obsessed with :) Is there an opportunity to add skill by adding geographical sophistication? Absolutely.