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Lord M Vader

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Re: The 2017 melting season
« Reply #3800 on: August 15, 2017, 05:45:01 PM »
While the DMI graph is notoriously unreliable the graph now shows 2017 to be behind both 2015 and 2016 wrt to the volume. Waiting for the mid-month update from PIOMAS will be very interesting now!

Neven wrote in his post that we dodged a cannonball this year, which I agree. But this luck can't go on forever, sooner or later we'll get a brutally bad melting season. Not to mention what will happen to the Arctic after next bigger El Niño which I think will emege by 2018/2019 and make the global temperature anomaly to overpower 2016 by 2019. That should be followed by a moderate to strong La Niña in 2019/2020.


VeliAlbertKallio

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Re: The 2017 melting season
« Reply #3801 on: August 15, 2017, 05:48:15 PM »
This year has seen Chukchi-East Siberian Sea having the 'blue ocean' season moving earlier melting, could this be partly due to prevailing winds pushing the ice edge towards FJL-Svalbard at the Atlantic edge. May be there is a connection: late onset of the winter ice on the Atlantic front, preconditioning ice movement (weak ice therein), causing the Pacific end of ocean clearing early. Is the winter ventilation gained on the Atlantic > than insolation gain in the Beaufort-Chukchi-ESS? May be this is just related to something like warm winter in Russia, is cold winter in Canada, vice versa type of thing? May be it isn't lopsided atmospheric polar hat, but same with sea ice as well?

<snip>
<snip> Indeed, it appears that the 'blue ocean' season is primarily extending in the opposite direction, towards Oct-Nov-Dec rather than Aug-Jul-June. If so, then encroaching atlantification is becoming a key driver of observed sea ice trends, at least around to the Laptev.

Here, we show that recent sea ice reductions, weakening of the halocline, and shoaling of the intermediate-depth Atlantic Water layer in the eastern Eurasian Basin [Laptev] have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin [Barents]. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin.


weatherdude88

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Re: The 2017 melting season
« Reply #3802 on: August 15, 2017, 06:14:21 PM »

Neven wrote in his post that we dodged a cannonball this year, which I agree. But this luck can't go on forever, sooner or later we'll get a brutally bad melting season.

I would argue the arctic got hit by Curlin's Proverbial "cannonball" this past winter. So if we had below average winter temperatures, with above average summer temperatures, would we have dodged the "cannonball"? I hypothesize the warm winter temperatures and their corresponding cooler summers over the last decade are a result of the same mechanisms. Weather patterns do not get stuck months let alone a year at a time. Classifying this as "luck" is nothing more than wishful thinking.

VeliAlbertKallio

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Re: The 2017 melting season
« Reply #3803 on: August 15, 2017, 06:19:38 PM »
The explanation for the current Laptev polyna is here: Even back in early 2000's when the Laptev Sea to north area was covered by very strong MYI, there appeared a tunnelling water current beneath sea ice that weakened it from that line. The sea ice began splitting down from the riparian deltas across the sea all the way to Canada. I believe that the shallow Siberian sea bed may also have additional subterranean rivers transport of water which takes water north. It could also be the collision of riparian discharges to saline oceanic water that causes turbulence that extracts heat from underlying warmer water source. Even a very thick and hard MYI could not prevent ice weakening and breaking in this area in 2000's, so the Laptev polnya isn't a miracle.  ;)

Does anyone have an explanation for the Laptev polyna? Considering how mobile the ice appears to be, I'm surprised not just that a hole would appear way off in the pack, but how persistent it is.

numerobis

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Re: The 2017 melting season
« Reply #3804 on: August 15, 2017, 06:56:11 PM »
Record-breaking temperatures across Nunavut:
http://www.nunatsiaqonline.ca/stories/article/65674arctic_heat_wave_sweeps_over_western_nunavut/

Daily records set Saturday and Sunday. A station record got set on Saturday

Looks to be centered around Queen Maud, which is where the ice blocking the NWP remains. Fair bit of ice there. Will the heat affect the extent much in that region, or only the volume?

werther

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Re: The 2017 melting season
« Reply #3805 on: August 15, 2017, 08:40:44 PM »
Numerobis, did you see yesterday's and today's MODIS tiles?
A weird layer of dust and smoke is colouring Victoria and Banks Island. It looks like terrible wildfires, for instance N of Lake Athabasca, are choking Nunavut and the CAA.
August is 6-9 dC warmer than normal in that region.
The taiga is burning, as well as the tundra....

A-Team

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Re: The 2017 melting season
« Reply #3806 on: August 15, 2017, 09:32:56 PM »
The first image below indicates that mid-August 2017 is not noteworthy compared to the finishing dates of 2016. These latter (right two columns) give some idea what the next 32 days might bring.

The animation of UH AMSR2 non-zero concentration ice runs from the 15 Sep 16 minimum to 13 Aug 17 at five day intervals. It is followed by a variation that shows open water as yellow, 0-50% UH AMSR2 concentration as purple (there's very little of it), and the rest as black. The final frame averages over the 67 days used to sample since the 2016 minimum. The two-frame shows remarkable retreat of the ice pack over the last month.
« Last Edit: August 15, 2017, 11:50:07 PM by A-Team »

numerobis

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Re: The 2017 melting season
« Reply #3807 on: August 15, 2017, 11:11:43 PM »
Numerobis, did you see yesterday's and today's MODIS tiles?
A weird layer of dust and smoke is colouring Victoria and Banks Island. It looks like terrible wildfires, for instance N of Lake Athabasca, are choking Nunavut and the CAA.
August is 6-9 dC warmer than normal in that region.
The taiga is burning, as well as the tundra....

Yukon and NWT have been burning all summer (along with BC, and I would assume Alberta). And with the heat wave there was an expectation that it would get worse. But I haven't read anything about it today.

numerobis

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Re: The 2017 melting season
« Reply #3808 on: August 15, 2017, 11:25:37 PM »
Kugluktuk current conditions is "smoke", and Taloyoak it's "haze".

The forecast calls for near-record temperatures throughout western Nunavut for the next several days yet, with a dump of black carbon as soon as it rains. "Wonderful."

Clyde River was near 20 C yesterday, snowing tonight apparently; back to warmth for the rest of the week according to the forecast. There's not much ice left there, this is just warming up the sea.

Dharma Rupa

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Re: The 2017 melting season
« Reply #3809 on: August 16, 2017, 12:26:50 AM »

Neven wrote in his post that we dodged a cannonball this year, which I agree. But this luck can't go on forever, sooner or later we'll get a brutally bad melting season.

I would argue the arctic got hit by Curlin's Proverbial "cannonball" this past winter. So if we had below average winter temperatures, with above average summer temperatures, would we have dodged the "cannonball"? I hypothesize the warm winter temperatures and their corresponding cooler summers over the last decade are a result of the same mechanisms. Weather patterns do not get stuck months let alone a year at a time. Classifying this as "luck" is nothing more than wishful thinking.

I'd tend to agree with this, with the mechanism being water vapor.  Remember that this Summer has only been a couple of degrees cooler than what we would call a Hot Arctic summer, and the poles are warming 10 times as fast as everything else.

Won't take much to have both a foggy Winter and a foggy Summer.  At that point I think we will have achieved WACC.

(I'm still not convinced this melting season ends in September -- at least for bottom melt.)

numerobis

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Re: The 2017 melting season
« Reply #3810 on: August 16, 2017, 02:54:10 AM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Csnavywx

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Re: The 2017 melting season
« Reply #3811 on: August 16, 2017, 02:59:03 AM »
Numerobis, did you see yesterday's and today's MODIS tiles?
A weird layer of dust and smoke is colouring Victoria and Banks Island. It looks like terrible wildfires, for instance N of Lake Athabasca, are choking Nunavut and the CAA.
August is 6-9 dC warmer than normal in that region.
The taiga is burning, as well as the tundra....

Yukon and NWT have been burning all summer (along with BC, and I would assume Alberta). And with the heat wave there was an expectation that it would get worse. But I haven't read anything about it today.

1.19 million acres burned over the last day in the NWT, so there's a massive smoke layer now. It's being advected directly into the CAA and will make it into the CAB with this heat wave. Temps are already soaring and should make it into the 70s tomorrow over the land portions of the CAA and into the 40s over ice.

Edit: This may end up being a significant meteorological event in terms of both melt and soot deposition over older ice areas. While it's late in the season for this soot/BC to really impact melt this year, excessive deposition over MYI will remain until the following melting season, when snowmelt uncovers it next year. Typically fires aren't big enough for this to be that much of an issue, but this event is 1) close by, 2) extreme in magnitude, 3) being advected over the ice in question for many days, so it might have an unusually big impact compared to normal.
« Last Edit: August 16, 2017, 03:08:05 AM by Csnavywx »

Kate

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Re: The 2017 melting season
« Reply #3812 on: August 16, 2017, 04:12:22 AM »
It has certainly rained a lot in Barrow this year. The grass has flourished and spread... and rain keeps falling


Csnavywx

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Re: The 2017 melting season
« Reply #3813 on: August 16, 2017, 05:43:48 AM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

1rover1

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Re: The 2017 melting season
« Reply #3814 on: August 16, 2017, 06:52:07 AM »
At risk of getting too far off topic, but noting the discussion of the Canadian wildfire smoke and trajectory, affecting melt, there is a website which forecasts hourly smoke levels in Canada based on the inputs of known fires, location, size, and weather.  Forecast does not extend all the way into the CAA, but some indication.

http://firesmoke.ca/forecasts/viewer/run/ops/BSC-CA-01/current/

Regarding the number of fires mentioned by Werther, Alberta has had a below average number of hectares burn this year (14,794 ha compared to 5 year average 294,000 ha).  Alberta sitrep here:  http://wildfire.alberta.ca/reports/sitrep.html

Somewhat more detailed, but here is Canada's national wildfire sitrep. http://www.ciffc.ca/firewire/current.php



greatdying2

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Re: The 2017 melting season
« Reply #3815 on: August 16, 2017, 07:10:52 AM »
Big drops in extent on the Pacific side again. Some also Atlantic and Russian sides, and a big area drop on the Russian side. The frequency and amplitude of area drop episodes on the Russian side are increasing and my guess is that it will start melting out within a week.

Attached Bremen 1 week 5-day 90 filter. See here for explanation and caveats:
http://forum.arctic-sea-ice.net/index.php/topic,2131.0.html .
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

Glenn Tamblyn

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Re: The 2017 melting season
« Reply #3816 on: August 16, 2017, 11:18:10 AM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

Question. What impact might so much open water appearing across the high CAB have in delaying this? Decreased albedo, ocean warming in those polynyas. How much does concentration have to drop before the coupling between the ice and 2m air temperatures starts to break down?

Bill Fothergill

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Re: The 2017 melting season
« Reply #3817 on: August 16, 2017, 12:26:39 PM »
...it appears as if they mechanically break when pulverizing. This surface topology of ice objects is an important cue that points towards mechanical breakage as the primary, driving mechanism...

VAK, have you seen this paper which deals with the variation in mechanical strength with temperature?

https://link.springer.com/article/10.1023%2FA%3A1021134128038

One snippet from there reads as follows...

2.3.1. Effects of temperature

Generally, the strength of ice increases with decreasing temperature in both tension and compression, as shown in Fig. 1. This temperature effect on strength is more prominent in compression than in tension. Haynes reported that the compressive strength of ice increased by approximately a factor of 4 from 0◦C to −40◦C. However, he indicated that the tensile strength of ice increased by only a factor of 1.3 over the same temperature range. Schulson has suggested that the temperature dependence of compressive strength of ice is related to ice dislocation and grain boundary sliding phenomena that lead to temperature-dependent damage accumulation. . The much more limited temperature dependence of tensile strength is related to the localisation of stress-accommodating mechanisms at the tips of tensile flaws.


With increased temperatures, there is a concomitant reduction in the mechanical strength of the sea ice, and this would tend to lead towards, in your words, "pulverisation". As progressively more energy is getting stored in the oceans, it would seem reasonable to hypothesise that this "pulverisation" may show an increasing trend with each passing melt season.

Niall Dollard

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Re: The 2017 melting season
« Reply #3818 on: August 16, 2017, 12:49:27 PM »
It has certainly rained a lot in Barrow this year. The grass has flourished and spread... and rain keeps falling

Not really on topic of the 2017 melt season, but feel I should reply to this with the actual rainfall stats for Barrow/Utqiaġvik.

June : Total = 0.25" (Avg=0.31"). 4 days with 0.01" or more precipitation (some of which was snow)

July : Total = 1.60" (Avg =0.98"). 13 days with 0.01" or more.

So unless August produces significantly wetter figures, it doesn't look particularly out of the ordinary.

F.Tnioli

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Re: The 2017 melting season
« Reply #3819 on: August 16, 2017, 01:17:34 PM »
This recent interesting paper, published online yesterday, may help further our understanding of the melting season a bit.

numerobis

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Re: The 2017 melting season
« Reply #3820 on: August 16, 2017, 01:39:35 PM »
Niall: total precip 50% higher than normal is notable.

In Iqaluit it was the number of days of precip that was particularly notable: instead of 40%, it was 87% (just four days without rain).

The impact on ice seems to be debated here. From walking the beach with growlers on it, it's clear to me that sun melts a heck of a lot faster than rain.

Niall Dollard

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Re: The 2017 melting season
« Reply #3821 on: August 16, 2017, 03:38:41 PM »
Niall: total precip 50% higher than normal is notable.


When monthly totals are low, percentage figures can run high/low very easily. eg. it could be said that June was "only" 81% of normal.  :)

Edit: I've attached the Alaskan precip percentiles for June & July. I don't see anything extraordinary. (other than record driest in central Alaska for July and record driest June in parts of the north slope).

I will though be closely watching the snowfall figures up north this autumn. 
« Last Edit: August 16, 2017, 04:00:50 PM by Niall Dollard »

oren

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Re: The 2017 melting season
« Reply #3822 on: August 16, 2017, 05:54:31 PM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

Question. What impact might so much open water appearing across the high CAB have in delaying this? Decreased albedo, ocean warming in those polynyas. How much does concentration have to drop before the coupling between the ice and 2m air temperatures starts to break down?
2016 was the first year that had widespread melting in the "high CAB", more noticeable in area stats than in extent numbers. On Sep 10th and Sep 11th the whole center refroze, while extent continued dropping for a few more days thanks to the periphery.
In order to delay refreezing I believe the whole area has to be clear of ice for at least a few days (weeks?) to allow mixing of the cold fresh water layer.
This year looks quite similar to 2016 around the pole. I therefore expect this year to have an early refreeze as well, before Sep 15th, unless some major compaction event magically brings all the ice to the center and clears the periphery.

VeliAlbertKallio

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Re: The 2017 melting season
« Reply #3823 on: August 16, 2017, 06:06:48 PM »
The rear-end (Pacific side) is far from the North Pole. Around the Bering end of the sea, the sun appears early but the 24-hour sunshine season is least pronounced. At NP midsummer insolation is the most intense, but very brief. So far, the North Pole's ice misses strongest sun way before surface melting starts. The cooling arrives there first and ice movement is most constricted - quite the opposite to the most extreme southern reaches around the Bering Straits end. Thus this may not be extrapolated indefinitely towards NP: "Findings from this study show that the feedback effect triggered by early-season divergent ice motion plays a key role in the seasonal evolution and interannual variation of sea ice retreat in the Pacific Arctic, particularly since the early 2000s."
This recent interesting paper, published online yesterday, may help further our understanding of the melting season a bit.
« Last Edit: August 16, 2017, 06:28:41 PM by VeliAlbertKallio »

VeliAlbertKallio

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Re: The 2017 melting season
« Reply #3824 on: August 16, 2017, 06:25:31 PM »
The reduction in compressive strength is crucial during warm winter and subsequent spring like 2016/2017 winter. In addition, pulverization itself leads to further weakening as sides and the ice fractures sitting in water leak in heat from sides and thus this a positive ice pulverization feedback.

I suspect, PIOMAS underestimates importance of switchover from 2D melt to 3D melt - as the sides have become far greater to add "side melt" to the "bottom melt". Notably, bottom melt and side melt continues weeks after surface melting has ended and I suspect PIOMAS isn't geared to see into 2D bottom melt becoming a 3D event. Ice may continue to soften too - keeping it fragile.

<snip>
<snip>the variation in mechanical strength with temperature https://link.springer.com/article/10.1023%2FA%3A1021134128038 <snip>
« Last Edit: August 16, 2017, 06:30:51 PM by VeliAlbertKallio »

Thomas Barlow

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Re: The 2017 melting season
« Reply #3825 on: August 16, 2017, 06:26:40 PM »
While the DMI graph is notoriously unreliable the graph now shows 2017 to be behind both 2015 and 2016 wrt to the volume.
I believe it is well within the margin-of-error of all the other institutions' data/graphs, and it is interesting to look at the trajectory of 2016.
2017 is actually catching up with it a little in the last week or so. If the melt-season extends, I could see it getting close. Only time will tell.
Neven wrote in his post that we dodged a cannonball this year, which I agree.
I'm not 100% convinced yet. This year looks like it could still be the lowest extent on record that occurred without without a major storm to assist the loss. Therefore, it is as bad as it can be. 
But this luck can't go on forever, sooner or later we'll get a brutally bad melting season.
I think the volume of the whole Arctic Ocean itself this year (not the N. Hemisphere, not the CAA, not Fram, not Baffin, etc.) will be at the lowest on record. That would be a disastrous outcome. Worse than 2012.
(Oren was tracking that Arctic Ocean volume - with CAA included - at one point)
Not to mention what will happen to the Arctic after next bigger El Niño which I think will emege by 2018/2019 and make the global temperature anomaly to overpower 2016 by 2019. That should be followed by a moderate to strong La Niña in 2019/2020.
I agree, more frequent El Nino's/La Nina's will get very disruptive. Although globally, some positive effects may occur in the very short-term, that will allow people to remain complacent for a bit longer.

Volume:
« Last Edit: August 16, 2017, 11:56:41 PM by Thomas Barlow »

Dharma Rupa

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Re: The 2017 melting season
« Reply #3826 on: August 16, 2017, 07:01:07 PM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

Question. What impact might so much open water appearing across the high CAB have in delaying this? Decreased albedo, ocean warming in those polynyas. How much does concentration have to drop before the coupling between the ice and 2m air temperatures starts to break down?
2016 was the first year that had widespread melting in the "high CAB", more noticeable in area stats than in extent numbers. On Sep 10th and Sep 11th the whole center refroze, while extent continued dropping for a few more days thanks to the periphery.
In order to delay refreezing I believe the whole area has to be clear of ice for at least a few days (weeks?) to allow mixing of the cold fresh water layer.
This year looks quite similar to 2016 around the pole. I therefore expect this year to have an early refreeze as well, before Sep 15th, unless some major compaction event magically brings all the ice to the center and clears the periphery.

That would be after the Dec 2015 switch to a maritime climate.

I'd not be suprised by an early refreeze near the pole.  It is not at all clear to me that really means anything.  I will be looking at areal temperature over Winter....   Ooops Off topic.

I want to know what this season looks like....after the end.


Shared Humanity

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Re: The 2017 melting season
« Reply #3827 on: August 16, 2017, 08:00:12 PM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

Question. What impact might so much open water appearing across the high CAB have in delaying this? Decreased albedo, ocean warming in those polynyas. How much does concentration have to drop before the coupling between the ice and 2m air temperatures starts to break down?
2016 was the first year that had widespread melting in the "high CAB", more noticeable in area stats than in extent numbers. On Sep 10th and Sep 11th the whole center refroze, while extent continued dropping for a few more days thanks to the periphery.
In order to delay refreezing I believe the whole area has to be clear of ice for at least a few days (weeks?) to allow mixing of the cold fresh water layer.
This year looks quite similar to 2016 around the pole. I therefore expect this year to have an early refreeze as well, before Sep 15th, unless some major compaction event magically brings all the ice to the center and clears the periphery.

As the sea ice has become increasingly fractured and mobile, there is a 4 decade trend towards increased dispersion at minimum. Do not expect a compaction event this fall. This is the new Arctic.

Pavel

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Re: The 2017 melting season
« Reply #3828 on: August 16, 2017, 08:16:50 PM »
The north of Greenland cools now, it's about -10 °C today. Air temperatures in the ocean still above melting point.
The animation below shows snapshots in 8 AUG and today.
Need a click

Pi26

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Re: The 2017 melting season
« Reply #3829 on: August 16, 2017, 09:08:53 PM »
The north of Greenland cools now, it's about -10 °C today. Air temperatures in the ocean still above melting point.
The animation below shows snapshots in 8 AUG and today.
Need a click


And in 13th august the situation there was also clearly visible.

A-Team

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Re: The 2017 melting season
« Reply #3830 on: August 16, 2017, 11:07:15 PM »
DR wants to know what this season looks like....after the end.
There is still a month to go until last year's minimum, not to mention warm water induced bottom melt that could continue well into October in some regions. We may yet see a surface manifestation of the anomalously mild fall and early winter, unless it has been neatly off-set (in the detrended sense) by cloudy summer weather.

If not, it's already worth contemplating what a hypothetical 'The Year in Review 2016/17' forum might contain.  Since open water on 15 Sep 16 was nearly half the area of the Inner Basin (1st graphic), it's worth tracking what became of it over the yearly cycle.

This region should be called the Arctic Ocean but isn't. Some committee decided in the 1950's to throw in the Barents and Greenland seas and maybe the Bering and inland Canadian waters as well. Consequently to determine an accurate areal figure for the Inner Basin (to enable percentile scoring of sea ice concentration maps), it becomes necessary to mask out extraneous cells on an equal area grid.

By 29 Dec 16, open waters of the Inner Basin had frozen up and so defined the first year ice FYI. Under the cafeteria tray model of the Arctic Ocean (first in, last out FILO or here first freeze, last melt FFLM), the open water latest to freeze (ie the Chukchi) is the first to melt, with the overall annual pattern eFYI .. mFYI .. lFY .. lFYI .. mFYI .. eFYI for early, middle and late ice.

Actually that monthly classification could be refined considerably using the 107 daily maps of the refreeze period, though weekly gives a more manageable partition of FYI ice classes. Bulk and shear movement of the ice pack, along with compaction and dispersion, can confuse the issue in some years though not so much in this one. Note too late-to-form ice can catch and even pass up early ice if transported to colder waters and weather.

The animation below marks up newly formed FYI in 5-day increments for both the freeze and melt seasons (using boolean differencing on a tiled-up overlay that pairs each interval with the previous). Twenty frames in mid-winter were uninformative (stationary) and were dropped.

It would be good to assign distinct colors to new ice to each of the 21 freeze frames to see what becomes of the FYI partition during the 22 melt frames. However that gets complex in a hurry as the melt season only time-reverses the freeze season to a 0th approximation, if that. (However it's not to easy to tell them apart running the animation backwards.)

To a certain extent, this process is captured by the diffuse colors of the annual Hycom thickness maps as there's little confusion between sub-2m FYI and older ice. That's included below for similar dates as the UH AMSR2 animation of FYI ice classes. The latter does not provide support for the Hycom ice finger discussed up-forum.

FishOutofWater

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Re: The 2017 melting season
« Reply #3831 on: August 17, 2017, 12:37:23 AM »
There are subtle cracks through most of the CAA "garlic press" now. The record heat and strong winds that have pounded northern Canada are taking a toll on the ice. It's all going to be moving soon and the Perry channel can move large amounts of fresh water and multi-year ice.

The smoke on the WV Aqua image obscures the surface but there are many growing cracks.

A-Team

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Re: The 2017 melting season
« Reply #3832 on: August 17, 2017, 01:14:15 AM »
Here is another perspective on developments from 14 July to 15 August -- the daily differences as seen with the Bering Strait at bottom. The animation runs forward and back.

Glenn Tamblyn

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Re: The 2017 melting season
« Reply #3833 on: August 17, 2017, 01:09:39 PM »
WTF

Looking at the last few days of Uni Bremen concentration maps. How can it vary so much?

Is this the ice doing something weird? Is this a programming/algorithm issue. How can concentration variations sweep across the basin so radically?

numerobis

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Re: The 2017 melting season
« Reply #3834 on: August 17, 2017, 02:51:25 PM »
The Bremen maps seem pretty vulnerable to clouds IMO.

F.Tnioli

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Re: The 2017 melting season
« Reply #3835 on: August 17, 2017, 02:52:39 PM »
WTF

Looking at the last few days of Uni Bremen concentration maps. How can it vary so much?

Is this the ice doing something weird? Is this a programming/algorithm issue. How can concentration variations sweep across the basin so radically?
I blame the "soup" state for this kind of things. Sensors get crazy when ice is in pieces of all kinds of size, most of them wet, some of them with ponds, and often times with plenty slush around. Plus, now there is dramatic insolation variability within 24h cycle, so some refreezing may change to more melting on hourly basis at places, adding and removing just a bit of ice to step through and back the treshold sensors detect as 'ice'. IMHO... Clouds add even more uncertainty.


Sterks

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Re: The 2017 melting season
« Reply #3837 on: August 17, 2017, 04:37:50 PM »
NASA Worldview shows that today (17 Aug 2017) the North Pole (90 North) sea ice has pulverized:
Looking at these images, don't you get a feeling of observing same image and again year after year, since 2013?
I agree the ice is pulverized, but in most of the places it is in a continuous state of pulverization, then it regenerates in Winter (if so happens) and then thicker MYI appears in Spring, less pulverized (if so happens).
No?
So what we just need is a string of cold winters without the stream of storms from the Atlantic that so pervasive they were in 2015 and 2016. Or sufficiently cold winters (if so ever happens)

meddoc

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Re: The 2017 melting season
« Reply #3838 on: August 17, 2017, 04:39:31 PM »

I blame the "soup" state for this kind of things. Sensors get crazy when ice is in pieces of all kinds of size, most of them wet, some of them with ponds, and often times with plenty slush around. Plus, now there is dramatic insolation variability within 24h cycle, so some refreezing may change to more melting on hourly basis at places, adding and removing just a bit of ice to step through and back the treshold sensors detect as 'ice'. IMHO... Clouds add even more uncertainty.

That's why I say as aPhysician, You have got to look at physical Status as well, not just numbers & parameters.
Extreme Weather Frequency and Severity & collapsed Jestream & crossing the Equator indicate significantly worse State of Arctic Ice.

Tigertown

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Re: The 2017 melting season
« Reply #3839 on: August 17, 2017, 05:55:33 PM »
 meddoc
That's why I say as aPhysician, You have got to look at physical Status as well, not just numbers & parameters.
Extreme Weather Frequency and Severity & collapsed Jestream & crossing the Equator indicate significantly worse State of Arctic Ice.
In other words holistic ice diagnostics.

werther

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Re: The 2017 melting season
« Reply #3840 on: August 17, 2017, 06:08:16 PM »
Glenn, hi,
Indeed UniBremen shows variations. Last days compactness seems to have tightened. When MODIS is analysed, it shows that first considerable snow has fallen N of the CAA and Greenland.
The pack is still pretty broken up, but most features are now less visible. The fresh cracks however show up immediately, still indicating the weakness of the pack.
I've compared to MODIS 20 August '13.
Then, there still was a 'safe haven' of about 1,2 Mkm2 structured pack ice N of the CAA. There's nothing left nowadays.
It is a 5 Mkm2 spread out ice debris field.
In all mean yearly averages, this year will show to be the worst since the beginning of satellite survey.

meddoc

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Re: The 2017 melting season
« Reply #3841 on: August 17, 2017, 06:20:56 PM »
meddoc
That's why I say as aPhysician, You have got to look at physical Status as well, not just numbers & parameters.
Extreme Weather Frequency and Severity & collapsed Jestream & crossing the Equator indicate significantly worse State of Arctic Ice.
In other words holistic ice diagnostics.

Not really.
Insurance Companies already state the first 6 Months are already at Last Year's Total Insurance Claims.
US Crops- Production already failed by 50%
Canada NW Wildfires just doubled in a Day.
A lot of Time still to Equinox. The Batteries (Oceans) will be fully charged after that, too, amplified by further Feedbacks (such as Wildfires).
And not to mention uncessated human Fossil Fuel Burning 24/7, all 12 Months on.

JMP

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Re: The 2017 melting season
« Reply #3842 on: August 17, 2017, 07:40:28 PM »
Insurance Companies already state the first 6 Months are already at Last Year's Total Insurance Claims.
US Crops- Production already failed by 50%
Canada NW Wildfires just doubled in a Day.
A lot of Time still to Equinox. The Batteries (Oceans) will be fully charged after that, too, amplified by further Feedbacks (such as Wildfires).
And not to mention uncessated human Fossil Fuel Burning 24/7, all 12 Months on.

Could you please provide something to back up your claims? Now, overall storm activity is likely and so total catastrophic events may indeed be worsening, but if you're going to present statements as facts rather than opinion - we appreciate data to back these up.

For instance, regarding Last Year's Total Insurance Claims -  I'm seeing contradictory information, that overall natural catastrophe claims were actually lower in the first half of 2017. 

Then, saying "US Crops- Production already failed by 50%" seems perhaps an exaggeration at best.  And, since I also see the link below states that "the highest overall losses in the first half-year were caused by the floods in Peru" so, therefore being not any U.S. losses that you mention, this too gives me doubt about this particular claim.   

 
https://www.munichre.com/us/property-casualty/press-news/press-releases/PressRelease-2017/NatCat2017/index.html


<Off-topic, take it elsewhere. Replies to this comment will be snipped; N.>
« Last Edit: August 17, 2017, 10:14:57 PM by Neven »

iceman

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Re: The 2017 melting season
« Reply #3843 on: August 17, 2017, 07:43:43 PM »
This recent interesting paper, published online yesterday, may help further our understanding of the melting season a bit.

Good find, a few notes:
     "... divergent ice motion in the early melt season triggers large-scale feedback which subsequently amplifies summer sea ice anomalies. The magnitude of divergence controlling the feedback has doubled since 2000 due to a more mobile ice cover..."
     They're talking about normal gyre-and-drift-related motion, not owing to larger or more frequent storms. 
     This divergence doesn't make a big difference in early-season ice concentration, but it's amplified by ice-ocean albedo feedback:
     "...although the direct contribution of doubled divergent ice motion after 2000 to the ice concentration reduction is small, this trigger accelerates ice melt through the enhanced solar heat input over the open water fraction..."
      Is it too big an inferential leap to say that trend risks destabilizing the Arctic regime?
      "... heat input through the open water fraction is the primary driver of seasonal and interannual variations in Arctic sea ice retreat..."

Figure 2 from the paper:

Shared Humanity

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Re: The 2017 melting season
« Reply #3844 on: August 17, 2017, 08:43:08 PM »
Great paper! The physical state of the ice is unlike anything we have ever seen, pulverized and highly mobile. This paper helps explain some of what we are seeing. It also has brought us back on topic.

Thank you.

Sterks

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Re: The 2017 melting season
« Reply #3845 on: August 17, 2017, 10:49:14 PM »
Unfortunate selection of wording though, "divergence" where actually the opposite "compaction" due to Beaufort Gyre for example, is what causes early drift of the ice away from the coasts, letting open ocean behind (what they call divergence).

FishOutofWater

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Re: The 2017 melting season
« Reply #3846 on: August 18, 2017, 12:01:14 AM »
Strong high pressure episodes of the Beaufort high cause divergence on the north shore of Alaska. Ekman pumping brings relatively warm water (not very warm actually) up from depths well below the fresh water surface layer after strong wind events.

I suspect that strong high pressure events in September can store a lot of summer's remaining heat in the Beaufort high. One reason that we've seen early melt in the Beaufort is that heat can winter over in the large dome of relatively fresh water in the Beaufort high.

I think that's one reason why this year's melt pattern looks like it does despite a cool July. I think that heat wintered over.
« Last Edit: August 18, 2017, 01:23:28 AM by FishOutofWater »

Sterks

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Re: The 2017 melting season
« Reply #3847 on: August 18, 2017, 12:09:44 AM »
FOOW why do you call it divergence?
Divergence, in geophysics, is an inherited concept from the Mathematics it uses as
                     div • v
where div is the divergence operator and v is a vector.
I am sorry. It is a too frequent concept, they should use another word.
Off topic, my apologies.

J Cartmill

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Re: The 2017 melting season
« Reply #3848 on: August 18, 2017, 12:43:13 AM »
It is divergence. The vector field is the wind field.
More here:
http://glossary.ametsoc.org/wiki/Divergence

FishOutofWater

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Re: The 2017 melting season
« Reply #3849 on: August 18, 2017, 01:32:14 AM »
See http://muenchow.cms.udel.edu/classes/Arctic/05_Ekman.pdf
or look up Ekman pumping on wikipedia

Understanding Ekman pumping and the Beaufort high is the key to understanding the melting patterns we have seen in recent years on the Alaskan side of the Arctic ocean. There have been multiple papers on Alaskan coastal upwelling in recent years. It has been increasing.