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Tigertown

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Re: The 2017 melting season
« Reply #2950 on: July 19, 2017, 06:33:00 AM »
McClure Strait and Parry Channel.
Too big of a file. I had to Youtube it.





« Last Edit: July 19, 2017, 07:06:53 AM by Tigertown »

S.Pansa

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Re: The 2017 melting season
« Reply #2951 on: July 19, 2017, 07:46:58 AM »
Here are the latest TOPAZ4 volume forecasts, in pictures and numbers (by pixel-count)

(T4 volume 071517: 7440 km³)
T4 volume 071817: 7220 km³
T4 volume 072617: 6270 km³ (loss rate 18th to 26th: ~120 km³/day, 1st half of July 170km³/day)

Two remarks.
- Speaking in relative terms, the Topaz4 volume loss for the fist half of July mimicked the Piomas one pretty closely (~26% - if my math is correct). Will be interesting to see if this continues. The June-losses were also very close, the relative losses in May though showed a huge difference .

- While the forecasts for the 23rd and especially the 27th are probably too fare out, I think they highlight how vulnerable the ice currently is, especially in the sector north of the Wrangle Island. 
The predicted changes in this area (red polygon in the third pic) are staggering. All it needs is a unspectacular low (990hPa) in the latest ECMWF run (12h, see last image).

This might or might not come to pass. But I think it shows how assailable the ice there is. If we are unlucky we could see a lot of open water there by early August.
And then, just imagine a strong low over this area in the weeks that follow. It would have a lot of relatively warm water to play with (what A-Team called the dangerous zone?). ... but we'll see.
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Tigertown

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Re: The 2017 melting season
« Reply #2952 on: July 19, 2017, 08:03:28 AM »
S.Pansa,
Quote
(T4 volume 071517: 7440 km³)


That is awfully close to JAXA right now, and it seems that PIOMAS is coming up a little thick in spots. Either way, there is a good deal of warm rain still falling hither and thither. It may just be more damaging to thickness than extent, and it could potentially continue even after insolation begins to wane. Imagine what a big loss of volume in August, it being thirty one days long, could do.

bairgon

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Re: The 2017 melting season
« Reply #2953 on: July 19, 2017, 08:48:22 AM »
McClure Strait and Parry Channel.

This shows that the ice has collapsed almost overnight, fracturing at both the western and eastern end of this channel.

As this is my first year watching a melt season via satellite, I have no experience of whether this is normal or not.

What mechanism could account for this? Is it bottom melt which has thinned the ice to a critical point?

JayW

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Re: The 2017 melting season
« Reply #2954 on: July 19, 2017, 09:35:29 AM »
dprog/dT has been to increase the strength of this cyclone according to the ECMWF, still 96+ hours away however.


http://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=nhem&pkg=z500_mslp&runtime=2017071900&fh=24&xpos=0&ypos=524
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Tigertown

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Re: The 2017 melting season
« Reply #2955 on: July 19, 2017, 10:13:57 AM »
 

This shows that the ice has collapsed almost overnight, fracturing at both the western and eastern end of this channel.

As this is my first year watching a melt season via satellite, I have no experience of whether this is normal or not.

What mechanism could account for this? Is it bottom melt which has thinned the ice to a critical point?

There has been a warm breeze blowing over land, including the CAA for weeks now, sometimes up to 10oC in some areas. Plus, waves contributed.

Thawing Thunder

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Re: The 2017 melting season
« Reply #2956 on: July 19, 2017, 11:09:39 AM »
On the atlantic side seems something to happen I rather expected on the pacific side. The storms must have caused a lot of damage. Also, the supposedly abnormally thick ice next to FJL turns out to consist of polynyas (which, admittedly, is better visible on the Uni Hamburg image) ...
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liefde

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Re: The 2017 melting season
« Reply #2957 on: July 19, 2017, 11:18:02 AM »
2016 was hottest or second hottest on record across the arctic from Sep to  Dec and in the top  5 from June - Aug.  This year is unlikely to be anywhere near that hot and I would expect  the October peak to be much closer to  normal than last year.
Have you taken into consideration how there has not been any growth to speak of in 2017? There has not been one month of 'normal' ice since about mid September 2016. So if 2017 would have to pick up in being cold enough for new ice, it sure is taking long..
Seen this latest graphing by Gavin? https://twitter.com/ClimateOfGavin/status/887522165196820480/photo/1

meddoc

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Re: The 2017 melting season
« Reply #2958 on: July 19, 2017, 11:59:02 AM »
On the atlantic side seems something to happen I rather expected on the pacific side. The storms must have caused a lot of damage. Also, the supposedly abnormally thick ice next to FJL turns out to consist of polynyas (which, admittedly, is better visible on the Uni Hamburg image) ...

And that Hole just keeps on growing, eating up MYI in the right upper Corner of Greenland.
Meanwhile, from Portugal across France, Italy, Croatia and into Montenegro Wildfires are raging.
Not to mention the usual Suspects: Siberia, Canada NW & Alaska.

DrTskoul

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Re: The 2017 melting season
« Reply #2959 on: July 19, 2017, 12:01:08 PM »
2016 was hottest or second hottest on record across the arctic from Sep to  Dec and in the top  5 from June - Aug.  This year is unlikely to be anywhere near that hot and I would expect  the October peak to be much closer to  normal than last year.
Have you taken into consideration how there has not been any growth to speak of in 2017? There has not been one month of 'normal' ice since about mid September 2016. So if 2017 would have to pick up in being cold enough for new ice, it sure is taking long..
Seen this latest graphing by Gavin? https://twitter.com/ClimateOfGavin/status/887522165196820480/photo/1

Distributions look like worms or slugs moving forward....

Andreas T

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Re: The 2017 melting season
« Reply #2960 on: July 19, 2017, 01:59:34 PM »
...

This shows that the ice has collapsed almost overnight, fracturing at both the western and eastern end of this channel.

As this is my first year watching a melt season via satellite, I have no experience of whether this is normal or not.

What mechanism could account for this? Is it bottom melt which has thinned the ice to a critical point?
This can be seen on worldview clicking back through the years back to 2009. 2010 is interesting when after an early (May!) start to the breakup from the east to Stefanson island, a line held across Parry channel for a month.
The mechanism behind this is that the ice is not uniformly thick and has some cracks from movement during the winter. As it weakens from thinning and softening (due to warming, enlarging of brine channels) it will initially be supported along the coasts of several islands. When one of these supports (the ice along the coast) gives way the stresses in the remaining ice become stronger so that it is most likely that everything becomes mobile in a very short time.


Steven

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Re: The 2017 melting season
« Reply #2961 on: July 19, 2017, 02:28:26 PM »
Latest weekly MODIS 7-day composite image from Environment Canada:
I've converted this to an animation to enable easier comparison to 2012. What strikes me is how different the two years are. 2012 seems to have a lot more ice (though I know extent metrics say otherwise), but also has areas of much lower concentration inside the pack on the Pacific side.

Sea ice compactness at this moment seems to be substantially higher than in 2012, 2015 and 2016.

That is also the case for NSIDC sea ice compactness, which suggests that 2017 has fewer melt ponds and/or fewer holes in the ice pack than 2012, 2015 and 2016.




DavidR

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Re: The 2017 melting season
« Reply #2962 on: July 19, 2017, 02:57:36 PM »
Have you taken into consideration how there has not been any growth to speak of in 2017? There has not been one month of 'normal' ice since about mid September 2016. So if 2017 would have to pick up in being cold enough for new ice, it sure is taking long..
Last years October figure was a consequence of an exceptional decline in the September Ice in the Antarctic and an exceptionally low rate of growth in the Arctic in October.  I expect both areas to be more normal this year with the likely extent reaching about 25 million in October.  Not as high as previous years but higher than the low of 2016. which after all followed on the end of a long and virulent El Nino with global sea temperatures well above previous records. 
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gerontocrat

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Re: The 2017 melting season
« Reply #2963 on: July 19, 2017, 03:40:20 PM »
Have you taken into consideration how there has not been any growth to speak of in 2017? There has not been one month of 'normal' ice since about mid September 2016. So if 2017 would have to pick up in being cold enough for new ice, it sure is taking long..
Last years October figure was a consequence of an exceptional decline in the September Ice in the Antarctic and an exceptionally low rate of growth in the Arctic in October.  I expect both areas to be more normal this year with the likely extent reaching about 25 million in October.  Not as high as previous years but higher than the low of 2016. which after all followed on the end of a long and virulent El Nino with global sea temperatures well above previous records.

So far Antarctic Sea Ice is failing to oblige by returning to normal. Indeed, if refreezing from now to max is about average, a max of around 18 to 18.5 million km2 seems likely (Jaxa data). Assuming an Arctic (jaxa) minimum of around 4 to 4.5 million km2 gives a total of 18 to 19 million km2. It is therefore quite possible that global sea ice extent may continue to decline for the time being.
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Pmt111500

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Re: The 2017 melting season
« Reply #2964 on: July 19, 2017, 03:42:45 PM »
Have you taken into consideration how there has not been any growth to speak of in 2017? There has not been one month of 'normal' ice since about mid September 2016. So if 2017 would have to pick up in being cold enough for new ice, it sure is taking long..
Last years October figure was a consequence of an exceptional decline in the September Ice in the Antarctic and an exceptionally low rate of growth in the Arctic in October.  I expect both areas to be more normal this year with the likely extent reaching about 25 million in October.  Not as high as previous years but higher than the low of 2016. which after all followed on the end of a long and virulent El Nino with global sea temperatures well above previous records.
We'll see if the Weddel and Ross Gyres partially responsible for the flatlining last autumn have recovered to their former levels of ice. I wouldn't be surprised by large gains there compared to last year. But arctic is another matter. I expect the autumn peak be a bit higher than 2016 but not back within the main pack.
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oren

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Re: The 2017 melting season
« Reply #2965 on: July 19, 2017, 04:09:35 PM »
Gents, could I kindly ask to put some limit on discussing Antarctic/global sea ice in this high-profile thread? Not that it's not interesting, but I feel it's veering OT.

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Re: The 2017 melting season
« Reply #2966 on: July 19, 2017, 05:23:11 PM »
Sea ice compactness at this moment seems to be substantially higher than in 2012, 2015 and 2016.
That is some good news at least. Thanks.
Could slow down the rest of the melt-season. A huge area of icepack towards 'west' side of the NP looks somewhat integrated from looking at Worldview.

Tigertown

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Re: The 2017 melting season
« Reply #2967 on: July 19, 2017, 05:37:06 PM »
Sea ice compactness at this moment seems to be substantially higher than in 2012, 2015 and 2016.
That is some good news at least. Thanks.
Could slow down the rest of the melt-season. A huge area of icepack towards 'west' side of the NP looks somewhat integrated from looking at Worldview.
I would have to trust my own eyes on that(compactness of any measure), among other sources.


PS   Unrelated.

NSIDC SIE
2017,    07,  17,      7.765  x 106 km2
2017,    07,  18,      7.640

Following a couple of nominal drops, yesterday saw a 125 k drop in extent.


« Last Edit: July 19, 2017, 05:46:17 PM by Tigertown »

magnamentis

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Re: The 2017 melting season
« Reply #2968 on: July 19, 2017, 05:41:57 PM »
Sea ice compactness at this moment seems to be substantially higher than in 2012, 2015 and 2016.
That is some good news at least. Thanks.
Could slow down the rest of the melt-season. A huge area of icepack towards 'west' side of the NP looks somewhat integrated from looking at Worldview.

would be good news if it were true while the exact opposite is the case IMO. looking at the entire remaining ice as a whole, compactness is poorest ever and meltponds are water ON ice and for that the ice most be relatively homogeneous and "compact" which it is not and besides other factors meltwater is often draining throuch fissures and holes.

ice is fragmented like never before which is the opposite of compact.

according to that the opposite will happen, the ice, despite the relatively cool and often overcast weather, will melt from the bottom and because its thinner than usual (a lot thinner in fact) and then considering that huge areas of ice have a similar thicknes, namely FYI, it could well happen that once zero thickness is reached, that huge areas will be affected quasi overnight.

last but not least we are at all times close to lowest even though the weather and temps are not especially melt-boosting for quite some time now. the worse it will be once that would change again with strong winds and wave action as nasty helpers to destroy ice.

i will happily stand corrected but let's see.

BTW it would be nice if we could have a link of the source for "high compaction" for further assessment of accuracy and reliability of that source.

any good points to proof me wrong are very welcome, facts should prevail ;)

EDIT: it has to be put into account where what happens, since the polar region is not expected to go generally ice-free. it's the latitudes between 77 and 82 north that count, the more southern rest will mostly melt anyways

Tigertown

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Re: The 2017 melting season
« Reply #2969 on: July 19, 2017, 05:58:05 PM »
magnamentis,
Quote
BTW it would be nice if we could have a link of the source for "high compaction" for further assessment of accuracy and reliability of that source.

It says NSIDC on the charts and the percentages are probably correct in and of themselves. I believe the problem may be that the percentage of compactness now compared to what we started out with is not saying much. If we had started the season out with a strong pack and still had a strong percentage of compactness, that would be a whole different situation. I am sure someone will correct me if I am wrong on how the NSIDC does their figuring.

Pavel

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Re: The 2017 melting season
« Reply #2970 on: July 19, 2017, 06:13:40 PM »
Quote
huge areas of ice have a similar thicknes, namely FYI, it could well happen that once zero thickness is reached, that huge areas will be affected quasi overnight
That's what I expect in August. I don't belive the FYI that formed after october-november can really survive the melting season.

greatdying2

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Re: The 2017 melting season
« Reply #2971 on: July 19, 2017, 08:06:03 PM »
NSIDC area/extent  is disproportionately affected  by melt polds
Because of this, "compactness" is a misleading name for this metric, which combines two distinct phenomena: the ratio of ice to open sea area (bona fide compactness), and the ratio of melt ponds to ice area.

This makes interpreting NSIDC area/extent tricky at best. It is entirely possible that reduced melt ponds due to increased fragmentation may be a negative feedback, slowing melt. Or, it may be the opposite. I haven't seen anything beyond speculation to resolve this important question.
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seaicesailor

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Re: The 2017 melting season
« Reply #2972 on: July 19, 2017, 08:35:12 PM »
I had removed my original comment, I was thinking it didn't add anything new. Anyway I'll just say the NSIDC compactness (derived from Wipneus processed data, I believe) support, for me, what I could perceive from the Canadian Servive composite images of a colder state of the Arctic ice pack in general compared to 2012.
See oren's gif and comment here
https://forum.arctic-sea-ice.net/index.php/topic,1834.msg121401.html#msg121401
« Last Edit: July 19, 2017, 08:43:03 PM by seaicesailor »

Thomas Barlow

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Re: The 2017 melting season
« Reply #2973 on: July 19, 2017, 08:51:10 PM »
Sea ice compactness at this moment seems to be substantially higher than in 2012, 2015 and 2016.
Quote
Thomas Barlow
That is some good news at least. Thanks.
Could slow down the rest of the melt-season. A huge area of icepack towards 'west' side of the NP looks somewhat integrated from looking at Worldview.

Quote
magnamentis
would be good news if it were true while the exact opposite is the case IMO.
Quote
Tigertown
I would have to trust my own eyes on that(compactness of any measure), among other sources.

Here you go.
Shows nearest least-cloudy day in 2016 ( bottom), compare to July 17 2017 (on top),
« Last Edit: July 20, 2017, 05:36:58 AM by Thomas Barlow »

Neven

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Re: The 2017 melting season
« Reply #2974 on: July 19, 2017, 08:53:03 PM »
would be good news if it were true while the exact opposite is the case IMO. looking at the entire remaining ice as a whole, compactness is poorest ever and meltponds are water ON ice and for that the ice most be relatively homogeneous and "compact" which it is not and besides other factors meltwater is often draining throuch fissures and holes.

ice is fragmented like never before which is the opposite of compact.

i will happily stand corrected but let's see.

You're not correct and need to do more comparing. Start here, Uni Bremen comparison maps for July 19th. Look for yellow and green in 2012, 2007, 2015 and 2016. Now compare to this year.

Quote
BTW it would be nice if we could have a link of the source for "high compaction" for further assessment of accuracy and reliability of that source.

Here's the Regional Graphs page on the ASIG, which contains a Wipneus graph with Uni Hamburg, JAXA and NSIDC compactness. As you can see, this year is highest for NSIDC and JAXA, but third highest for Uni Hamburg (highest resolution), not much above 2012.

This makes interpreting NSIDC area/extent tricky at best. It is entirely possible that reduced melt ponds due to increased fragmentation may be a negative feedback, slowing melt. Or, it may be the opposite. I haven't seen anything beyond speculation to resolve this important question.

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:
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Steven

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Re: The 2017 melting season
« Reply #2975 on: July 19, 2017, 08:57:00 PM »
Quote
BTW it would be nice if we could have a link of the source for "high compaction" for further assessment of accuracy and reliability of that source.

See this file on Wipneus' website for Arctic sea ice extent and area data calculated from NSIDC gridded sea ice concentration.  The numbers in the third column of that file corresponds to sea ice extent, the fourth column to area, and the last two columns correspond to the extent and area anomalies respectively. 

From those data you can then calculate NSIDC compactness = area divided by extent.

See also the compactness graph in the top post of Wipneus' home brew thread:



There are 3 groups of curves in this graph.  The red/purple NSIDC curves correspond to the graph I posted upthread.  The green JAXA curves lead to the same conclusion, namely that compactness in 2017 is currently higher than in 2012, 2015, and 2016.  Finally, the third group of curves in the graph (blue Uni Hamburg curves) also show that compactness is currently higher than in 2015 and 2016.  Note that comparisons with 2012 cannot be made from Uni Hamburg data, since the Uni Hamburg AMSR2 data are only available from August 2012 onward.  (The graph does show some Uni Hamburg SSMIS data for July 2012, but that is not directly comparable to AMSR2).

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Re: The 2017 melting season
« Reply #2976 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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Re: The 2017 melting season
« Reply #2977 on: July 19, 2017, 09:43:08 PM »
There are 3 groups of curves in this graph.
Since no one has attempted to address the important issue of melt pond fraction vs. true compaction, and since many people seem to be jumping on the "2017 is more compact" bandwagon, I will make this further point: Look at how noisy these plots are.

I would speculate that a large part of this high short-term variability (aside from the part due to measurement error, etc.) is due to melt ponds. Weather can cause melt ponds to form and refreeze quickly over large areas. Bona fide compaction requires ice to be pushed around, so it takes longer (how long?).

If so, the contribution of melt ponds appears to be of the same order of magnitude as the difference between years in bona fide compaction.

Personally (and scientifically), I have a very hard time placing much weight on such noisy and AFAIK unsupported metrics. I'm not saying that this year bona fide compaction is less or more than other years, I'm just saying that IMHO, based on this metric, we don't really know. (Or perhaps I am just ignorant about the relevant scientific literature...?)
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magnamentis

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Re: The 2017 melting season
« Reply #2978 on: July 19, 2017, 10:54:16 PM »
magnamentis,
Quote
BTW it would be nice if we could have a link of the source for "high compaction" for further assessment of accuracy and reliability of that source.

It says NSIDC on the charts and the percentages are probably correct in and of themselves. I believe the problem may be that the percentage of compactness now compared to what we started out with is not saying much. If we had started the season out with a strong pack and still had a strong percentage of compactness, that would be a whole different situation. I am sure someone will correct me if I am wrong on how the NSIDC does their figuring.

good explanation, makes totally sense, thanks a lot, i did not consider that :-)

magnamentis

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Re: The 2017 melting season
« Reply #2979 on: July 19, 2017, 10:55:45 PM »
NSIDC area/extent  is disproportionately affected  by melt polds
Because of this, "compactness" is a misleading name for this metric, which combines two distinct phenomena: the ratio of ice to open sea area (bona fide compactness), and the ratio of melt ponds to ice area.

This makes interpreting NSIDC area/extent tricky at best. It is entirely possible that reduced melt ponds due to increased fragmentation may be a negative feedback, slowing melt. Or, it may be the opposite. I haven't seen anything beyond speculation to resolve this important question.

thanks a lot, today adds a lot to my learning curve thanks to many thoughtful feedbacks ;)

@neven

thanks for the links, i'll do as suggested (more comparison and the likes ) ;)

VeliAlbertKallio

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Re: The 2017 melting season
« Reply #2980 on: July 20, 2017, 12:17:30 AM »
The mysteries of the pulverized sea ice may continue. But there is one thing certain. It the open water between ice floes is large, the overall surface colour darkens (hence more sunlight retention). Despite seeing pulverized and fractured sea ice almost everywhere, huge areas appear still relatively white --> This means that sunlight continues to be dumped into space. If the whole ocean gets darker hues due to pulverization and/or ponding, then it will be bye-bye  ;)


... 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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Re: The 2017 melting season
« Reply #2981 on: July 20, 2017, 12:54:34 AM »
Quote
Personally (and scientifically), I have a very hard time placing much weight on such noisy and AFAIK unsupported metrics. I'm not saying that this year bona fide compaction is less or more than other years, I'm just saying that IMHO, based on this metric, we don't really know. (Or perhaps I am just ignorant about the relevant scientific literature...?)

Definitely in agreement on this. I think its very hard to pin down where we are by comparing any conventional metrics with past years. For a start perhaps as much as fifty percent of the "extent" being charted is a mobile mix of rounded off floes and rubble. And unless I'm mistaken these rubble areas which could be half of the actual area of these zones are below the resolution of algorithms being used to generate the data we are receiving. So (as an extreme example) say 100 sq km containing on average a football sized chunk or two per square meter dispersed evenly over the whole area could conceivably count as a solid 100 sq km of area and extent.
And my perception when I try to logic out the differences in the state of the ice from the massively different freeze season is that a lot of the Ice that is in the reasonably cohesive section nth of the CAA would have started its life near the Russian coast in Autumn conditions that were characterized by snowfalls on the water oscillating with sleet and above freezing temps and "snow-floes" might be a better description of them than Ice-Floes. These would have had difficulty building bottom thickness later in the season due to insulation properties of the "layercake" Then from February on when dry and cold conditions returned, the mobile snow-floes would have been set into a mesh of more saline late first year ice. which may well have built more thickness bottom down than earlier stuff with its snow blanket insulation. This sort of scenario could reduce meltponding via several mechanisms. Porosity of the "snow-floe" subset, Different elastic properties, and little strength in either set compared to previous years causing far more fracturing and drainage potential. And if there is less salinity in because of a lot of snow and sleet contributing to the early season stuff, then the lower melting point of the late FYI would, as it melts, tend to suppress water and air temperatures and retard melt in the earlier stuff .
Also regarding compaction metrics. previous years have been more characterized by the fringes being chiseled away and dispersed over relatively large areas. Giving large areas easily recognized as low concentration. Where as this year the increased mobility and fragility is causing a general sprawl out of rounded off floes and rubble fields.
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Ice Shieldz

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Re: The 2017 melting season
« Reply #2982 on: July 20, 2017, 03:10:14 AM »
As far as nullschool is concerned 2016 atlantic-side SSTAs were hotter than 2017's, while 2016 pacific-side SSTAs were significantly cooler. Not sure of the climatology or the weather that created this difference, but over the last 30 days, 2017's pacific-side SSTAs are clearly heating at a faster rate than 2016's, and therefore 2017 is closing the gap.

As someone alluded to earlier, an atlanticpacific-side warm ocean is said to drive WACCy like weather responses in fall-winter, but how will this effect summer-time systems in-bound from russia to the greenland sea?



Disclaimer: At least one poster commented that they don't trust nullschool's SST data. Not remembering why? I'm assuming that because we are comparing data from 2 different years in the same product, the differences in temps between now and 2016 are accurate enough as a measure of relative change.
« Last Edit: July 20, 2017, 05:10:51 AM by Ice Shieldz »

Tigertown

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Re: The 2017 melting season
« Reply #2983 on: July 20, 2017, 05:02:40 AM »
A fair amount of rain lining up with warm 850 mb temperatures today.
CLICK IMAGE

Hyperion

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Re: The 2017 melting season
« Reply #2984 on: July 20, 2017, 05:14:24 AM »
Heres a look at the Atlantic side 2015,2016,2017. SSTs and currents

To me there actually seems to be more gulfstream inflow this year than the two preceding. And definitely a lot more meltwater eviction down both of Greenlands coasts. and a substantial cold meltpool establishing this year to the south and east of Greenland also. Its interesting to see the ramp up of temperature from 8.7 to 9.2 to 15.8 degrees in the warm blob next to Svalbard.
Hansen 2015 warned about the danger of the meltpool south of Greenland. predicting that by covering the gulf-stream it could produce a world wide global warming effect up to ten times as much as our current greenhouse gas overburden. By reducing its ability to radiate heat away into space. If this effect is kicking in, then we might have an explanation for why there appears to be a lot less ice nth of Svalbard and Franz Josef Land than Piomass is claiming. Theres been persistent southerly's there for a while now, and waves created by them up to 3m spanking the ice in the vicinity. With the fragmented pack they are capable of penetrating perhaps 100km into the ice, and if gulf-stream waters are lurking below the cooler surface then considerable heat may be attacking the ice from below due to mixing processes. That meltpool also seems  effective in pinning a low pressure system to itself and with the high pressure stalled over western Europe, the southerly's have been and look to want to continue winching all the air and humidity all the way up from the Caribbean and gulf of Mexico.
Click to animate.
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Hyperion

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Re: The 2017 melting season
« Reply #2985 on: July 20, 2017, 05:20:32 AM »
A fair amount of rain lining up with warm 850 mb temperatures today.

Yer. And quite heavy over the best stuff we got north of the CAA too!
 :'(
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subgeometer

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Re: The 2017 melting season
« Reply #2986 on: July 20, 2017, 06:07:40 AM »
Windy TV predict persistent waves around 2m north of Svalbard this week while warm air is drawn over the Atlantic sector. Also plenty of waves on the Pacific front at various times

I'm not sure how this is determined but it's scary how far into the pack the model sees waves propagating

Tigertown

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Re: The 2017 melting season
« Reply #2987 on: July 20, 2017, 06:32:33 AM »
@subgeometer

It looks like that is going to continue around the Svalbard area for several days, with some ups and downs in wave heights, of course. This should move some of the warm water around, and there is plenty in the area.

subgeometer

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Re: The 2017 melting season
« Reply #2988 on: July 20, 2017, 11:04:24 AM »
@subgeometer

It looks like that is going to continue around the Svalbard area for several days, with some ups and downs in wave heights, of course. This should move some of the warm water around, and there is plenty in the area.

Thanks TT

It would also be interesting to see a few profile from the huge swathe of open water  around the coast from Canada to the Laptev.

The waves at Svalbard are being driven by persistent warm southerlies. This low could have a bad effect on the now peripheral Atlantic fringe, while the cold is blown to already melted areas on the Pacific side.


oren

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Re: The 2017 melting season
« Reply #2989 on: July 20, 2017, 02:59:27 PM »
Animation of Uni Bremen's concentration on the pacific side, July 13-19.
Note how floes are winking out north of Barrow and the front is receding, while the Gyre is pushing ice south in the eastern Beaufort, and what seems like dispersion north of Wrangel.

numerobis

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Re: The 2017 melting season
« Reply #2990 on: July 20, 2017, 04:05:21 PM »
Southern Baffin Island has had a cool, cloudy, and rainy July so far, so there's a fair bit more sea ice than normal. Cloudy is the main thing stopping sea ice from melting.

It's complicating the shipping season. The Amundsen is going to be stuck breaking ice for a bunch of ships in and out of Frobisher Bay over the next couple days -- the Mitiq, Qamutik, Zélada and Taiga all arrive and/or leave this week, along with a tanker whose name I've forgotten that's been filling up our huge diesel tanks.

Rumor is the Mitiq won't be able to get to Pangnirtung, so that town just won't get its scheduled shipment on Monday. That's not yet reflected in the schedule, so I guess the company is still holding up hope.

http://ice-glaces.ec.gc.ca/cgi-bin/getprod.pl?prodid=WIS33CT&wrap=1&lang=en
http://www.neas.ca/pdf/sailing_schedule.pdf
https://www.arcticsealift.com/schedule.php

Andreas T

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Re: The 2017 melting season
« Reply #2991 on: July 20, 2017, 04:22:18 PM »
nullschool predicted strong winds from Baffin into Frobisher Bay on the 18th, if I remember correctly. Did that happen and cause problems?

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Re: The 2017 melting season
« Reply #2992 on: July 20, 2017, 04:28:12 PM »
Southern Baffin Island has had a cool, cloudy, and rainy July so far, so there's a fair bit more sea ice than normal.
https://www.arcticsealift.com/schedule.php

some more here, some less there ;)

for the south it's true but the, close to land the average shows ice at this time of the year, nothing out of the ordinary really once we look at landlocked ice IMO, just some very local differences.
« Last Edit: July 20, 2017, 04:34:41 PM by magnamentis »

FishOutofWater

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Re: The 2017 melting season
« Reply #2993 on: July 20, 2017, 05:10:20 PM »
Judah Cohen made an excellent forecast of the Arctic weather on 2 July. The positive AO he predicted has kept the central Arctic cool and cloudy, preserving the central core of the sea ice.

Longer Term

30–day

The latest plot of the tropospheric polar cap geopotential heights (PCHs) shows cold/below normal PCHs in the stratosphere and in the troposphere over the next two week (Figure 10).   The cold/negative PCHs are consistent with the predicted positive AO and low heights in the Arctic basin.  Cold/negative PCHs does favor ridging and warmer temperatures at lower latitudes across Europe and the US though at this time of year the relationship is not strong.  The cold/negative PCHs could also help retard the rate of Arctic sea ice melt through the summer months.


With this stormy weather pattern ice along the Atlantic margins of the ice pack is vulnerable because warm water has been entering the Arctic through the Fram straight, flowing in along the west and northern coastline of Svalbard. This weather is not perfect like 2013 for preserving sea ice because the margins on the Siberian and Atlantic sides have seen strong warm air advection, but it has near perfect for preserving the core of ice in the central Arctic.

All in all the cool cloudy weather has been very good news for the ice this summer.

I'm closely watching how much damage is caused by storms and waves along the margins of the ice pack with the open water. I'm expecting a rapid retreat on the Atlantic side over the next 2 weeks.

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Re: The 2017 melting season
« Reply #2994 on: July 20, 2017, 05:24:29 PM »
This +AO/+NAO pattern has been very persistent, with very few breaks since last fall. Quite remarkable.

numerobis

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Re: The 2017 melting season
« Reply #2995 on: July 20, 2017, 06:02:25 PM »
nullschool predicted strong winds from Baffin into Frobisher Bay on the 18th, if I remember correctly. Did that happen and cause problems?

There isn't much ice at the mouth of Frobisher Bay to blow around, so I don't think it's caused any serious trouble. Still probably want an icebreaker nearby.

Pang is on a fjord off the next major bay (Cumberland Sound). There, the ice report has a couple of regions at 70-90% thick first-year ice with "vast" floes (several km wide). That could pretty easily get in the way of the entrance to the sound if the winds come from the north, or to both the entrance to the sound and the fjord if the winds come from the southeast. Presumably that's what's sparking unconfirmed rumours.

Seems the shipping companies expect the Baffin Sea to be navigable (but not necessarily ice-free) all the way up the coast by mid-August only. Qikiqtarjuaq, Clyde River, Pond Inlet, and Grise Fiord don't have deliveries until August 18 or later. Qik and Clyde are locked in by fast ice right now; it's got almost a month still to melt before causing trouble.

After that there's still a full extra month of melt season. Seems unlikely to have any more than a trace of ice survive in the Baffin Sea so long. The weather is "average" by 1980-2010 climatology; that still means it's a lot warmer than the 1980s.

Steven

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Re: The 2017 melting season
« Reply #2996 on: July 20, 2017, 07:26:24 PM »
There are 3 groups of curves in this graph.
Since no one has attempted to address the important issue of melt pond fraction vs. true compaction, and since many people seem to be jumping on the "2017 is more compact" bandwagon, I will make this further point: Look at how noisy these plots are.

NSIDC sea ice concentration should be more sensitive to melt ponds than the JAXA or Uni Hamburg data.  The fact that it is sensitive to melt ponds is actually useful for making predictions.  The NSIDC sea ice area in June (or July) is a good predictor for the September minimum.

Slater's probabilistic method is based on NSIDC sea ice concentration.  People like Chris Reynolds, Rob Dekker and Alek Petty have also been using NSIDC sea ice area (or concentration) to predict the September minimum in one way or another.  I also use it for my own estimates in the polls on this forum.

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Re: The 2017 melting season
« Reply #2997 on: July 20, 2017, 08:04:41 PM »
The Pacifics looking interesting. 8 hurricanes beaded from Japan to Panama. Quite a lot for this early in the season. Greedy looking settup dragging all the tropical air from Africa to Mexico and throwing it up the Asian coast. Looking at the 250hpa jets the polar jet has thrown out an arm and hybridised the second one from the left already. Bizzare cross equatorial backflows south at that level also.

850hpa with MSLP, and 250hpa with TPW
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Re: The 2017 melting season
« Reply #2998 on: July 20, 2017, 08:05:12 PM »
A few days of rough stormy weather ahead in the Beaufort sea, it will get cooler (eventually) as almost the whole Arctic proper, however these storms may disperse the neatly formed pack of broken floes in Beaufort. Still 60-90 days of bottom melt there.
Detail of ACNFS drift forecast for this Sunday, a couple of storms like this might make the thing look really messy as in '15 and '16

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Re: The 2017 melting season
« Reply #2999 on: July 20, 2017, 09:56:39 PM »
I also have this feeling that holes could start to show up in the ice pack real fast, once they get going. But for now, this year isn't looking anything like 2016, 2015, or even 2013. Here's a comparison using Uni Hamburg AMSR2 sea ice concentration maps:
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