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Aluminium

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Re: The 2018 melting season
« Reply #1500 on: June 21, 2018, 08:12:50 AM »
June 16-20.

deconstruct

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Re: The 2018 melting season
« Reply #1501 on: June 21, 2018, 09:40:13 AM »
<snip. This response is both too long and off-topic. This forum is for discussions on the current melting season, not diatribes on the invalidity of certain computer models. Please post those elsewhere. Thanks. JP>
« Last Edit: June 21, 2018, 11:57:59 AM by Jim Pettit »

uniquorn

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Re: The 2018 melting season
« Reply #1502 on: June 21, 2018, 01:06:06 PM »
Another surge of warm winds from the Pacific forecast from Sunday. ECMWF warmer than GFS this time.

Daniel B.

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Re: The 2018 melting season
« Reply #1503 on: June 21, 2018, 02:24:09 PM »
Happy solstice.  Thus far, the 2018 melt season has been fairly average.  According to NSIDC, melt is about 4% below the long-term average, and 6% below the 10-year average.  Interestingly, only two years this century have had less melt at solstice, 2007 and 2015. 

Lord M Vader

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Re: The 2018 melting season
« Reply #1504 on: June 21, 2018, 04:01:23 PM »
While the sea ice is melting in the Arctic basin it is still winter conditions and about 1 meter of snow on the ground in the far eastern Canada(!)

https://www.wunderground.com/news/2018-06-18-labrador-canada-snow-igloo-lake-lodge

About the melting season, there might be some changes during the next few weeks or so.

1) The GFS ensemble forecast for the next 4 weeks depicts more high pressure dominated weather over Beaufort and CAB.

2) According to Dr. Mike Ventrice,  as the standing La Niña wave has waned and a shift in the tropics is occurring, it will play a "a major role in changing weather patterns across the Northern Hemisphere later this Summer through Fall into Winter."

https://twitter.com/MJVentrice/status/1009187292232192002

If such shift is going to emerge, we may very well see a repeat of July 2015. I still don't see a new record low as likely due to the lack of melting momentum in May-June, especially in the high Arctic above 80N.

A-Team

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Re: The 2018 melting season
« Reply #1505 on: June 21, 2018, 05:45:08 PM »
Jaxa RGB has some promise for melt pond delineation despite the complexity of its color. Below, a fiducial reddish gray was picked (as a 7x7 average) that seemed to correspond to WorldView bluish melt.

It has been propagated across the 28 day time series in Gimp using the non-contiguous color picker at color space width of 20. Jaxa 'melt ponds' are shown in conjunction with imagery from the same dates from Ascat roughness (which transitions mightily after day 153 June 2nd) and UH AMSR2 sea ice concentration.

The most surprising melt feature is the principal Northwest Passage. This was pointed out up-forum by Oren (#?) based on cloud-free areas in WorldView. The Nares Strait is softening somewhat but not clear to ice export. Baffin Bay ice is rapidly disappearing.
« Last Edit: June 21, 2018, 05:59:14 PM by A-Team »

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Re: The 2018 melting season
« Reply #1506 on: June 21, 2018, 05:47:48 PM »
Here is a bigger version of that 2x2 of Jaxa, Jaxa melt ponds, Ascat, AMSR2. It provides twice the resolution of the 2x2 above suitable for download (though it is displaying, too widely, in my web browser and won't open in a separate tab in mac Opera, Chrome, Firefox or Safari though the latter will open it properly in QuickTime).
« Last Edit: June 21, 2018, 06:06:09 PM by A-Team »

magnamentis

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Re: The 2018 melting season
« Reply #1507 on: June 21, 2018, 06:57:34 PM »
it has certainly been mentioned but i think that it could be useful to pay more attention to cloud cover.

reason is that each time i look at the cloud cover, on first glance one gets the impression that most of the arctic ocean is cloud covered and this could explain, similarly to last year, why melting, the starting conditions and temps considered, is not exactly performing as many of us expected.

keyword is the surprise many expressed once the melting motor started to stutter, perhaps, paying more attention to cloudyness could take some of that surprise away.

for me it's the only explanation i found after the theory of flawed algorithms and questioning the 15% threshold (whether it's still contemporary or should sooner or later be thought over) did not find many supporters in this forum ;)
« Last Edit: June 21, 2018, 08:47:23 PM by magnamentis »

Hyperion

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Re: The 2018 melting season
« Reply #1508 on: June 21, 2018, 07:45:15 PM »
When you look at the sea level change since early may, the appearance to me is the Beaufort gyre is pushed up against the Chukchi plateau and unwinding. The tail of the comma shape is the combined outflow mixed with Pacific and Atlantic inflows and coincides with the region of -1.8C waters extended from north Chukchi to the elsmere island region of the CAA, this is why the Beaufort to Chukchi multi year stringer turns north and goes poof,  and why the extent loss has not progressed east in the Chukchi or north in the Beaufort. Melt is happening stronglynin the swath of the Comma and the result is the much larger than the Arctic basin negative SSTA area of the Atlantic. and nares spewing melt but not unclogging. If someone wants to enhance the -1.8 SST in a nullschool screenshot perhaps this would be clearer. Its easiest to see in their SSTA maps.
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Hyperion

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Re: The 2018 melting season
« Reply #1509 on: June 21, 2018, 07:50:10 PM »

http://robinwestenra.blogspot.com/2017/12/the-collapse-of-arctic-beaufort-gyre.html
The collapse of the Arctic Beaufort Gyre and what it means

Paul Beckwith describes this most serious of positive feedbacks in which a reversal in the Beaufort Gyre means that rather than ice being taken via the Fram Strait into the Atlantic warm water from the Pacific is being taken into the Arctic Basin via the Bering Strait.


Paul Beckwith on Loss of Arctic Air Inversion + Halocline


https://paulbeckwith.net/2017/12/13/unprecedented-collapse-of-the-arctic-beaufort-gyre/

Most significantly, the Arctic’s Beaufort Gyre collapsed. This unprecedented event in late 2016/early 2017 occurred with rapidly declining sea-ice, letting ever increasing numbers of stronger storms from the Atlantic to enter the Arctic, bringing moisture and more warming. A vicious cycle of cascading feedbacks…
JEC says:
May 24, 2018 at 7:07 am
Is the Beaufort Gyre reversing? June 2018 modeling suggests a low formation, but cant tell if its enough to kick out the strong high pressure in Arctic. Our trip around Hatteras last week, the north adverse currents very very strong, over 2 knots. Unusual as the Gulf Stream seems to be pushed more easterly due to it. West wall especially.


Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
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dosibl

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Re: The 2018 melting season
« Reply #1510 on: June 21, 2018, 07:53:13 PM »
magnamentis, is there any product for measuring cloud cover? I'm loathe to try and eyeball worldview pictures and draw any conclusions.

Hyperion

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Re: The 2018 melting season
« Reply #1511 on: June 21, 2018, 07:57:39 PM »
Wipneus excellent animation shows this also.
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
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A-Team

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Re: The 2018 melting season
« Reply #1512 on: June 21, 2018, 08:06:31 PM »
While the rain and melt events in early June have obliterated almost all trackable ice features on the 'upper' half (Siberian side) of Ascat imagery that are needed to follow wind-driven bulk motion, deformation and dispersion of the ice pack, one of them has persisted north of Severnaya Zemlya.

It originated in mid-September northeast of the New Siberian Islands, probably as a left-over stringer of thick CAA ice from two years ago. It has not travelled all that far since Jan 1st but still might make it out the Fram by this fall.

Some individual floes in the 'lower' half can still be followed even though most of them are reversed in roughness. The web of lineations seem to be shear lines rather than pressure ridges and they too have been stable since the melt transition, though they can't be tracked long-term without going to the more difficult Sentinel-1AB.

It would be great if people saying the Beaufort Gyre has reversed could explain why direct observational data doesn't support that idea -- talking about ice movement as there's no recent data on what's going on below. The motion of the Arctic ice pack is very complicated though still vaguely clockwise since mid-Sept 2017.
« Last Edit: June 21, 2018, 09:30:21 PM by A-Team »

oren

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Re: The 2018 melting season
« Reply #1513 on: June 21, 2018, 08:35:17 PM »
So I've been thinking about the apparent "slowness" of this year's extent behavior, and have come to the conclusion that a lot of it has to do with the Kara Sea. This is something that has been predicted in advance - a high volume calculated by PIOMAS during the max volume season made the ice less susceptible to early melting.
I've compiled a few charts to help drive that point home. Almost regardless of the current conditions, Kara volume and extent are expected to mostly disappear by September, potentially putting 2018 back in the race among the low extent years.
The first chart shows how 2018 maxed out very high on volume. But June started with impressive melting, and I expect this year to join all other recent years at the bottom later in the summer. Data courtesy of Wipneus.
The second chart shows how on day 135 (mid-May) 2018 had the highest Kara volume since 2005, even though on day 45 it was among the 5 lowest years. But on day 166 (mid-June) it's already correcting, though still very far from the leaders such as 2012 and 2016. And on day 260  (~minimum), all years since 2004 had virtually zero volume.
The third chart shows how extent in June has started to be highly variable in the Kara since 2010, but regardless of this variability has been highly consistent and very low at minimum.
Bottom line - 2018 has a "bank" of 300-400k km2 of extent that it could use to get back in the leading pack.
« Last Edit: June 21, 2018, 08:53:08 PM by oren »

magnamentis

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Re: The 2018 melting season
« Reply #1514 on: June 21, 2018, 08:51:00 PM »
magnamentis, is there any product for measuring cloud cover? I'm loathe to try and eyeball worldview pictures and draw any conclusions.

perhaps a few of the "Pros" know better sources but what i mean, beside the fact that
it applies today as well as each time i was looking in the past 2 weeks, are the ones
linked below.

i hope the link takes you directly to the right page and zoom level

https://www.windy.com/?clouds,66.089,-1.846,3

http://cci-reanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-tcld-topo

as neven said recently somewhere else, it's all about the weather and clouds to my limited understanding are part of that weather.

johnm33

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Re: The 2018 melting season
« Reply #1515 on: June 21, 2018, 09:17:38 PM »
On A-teams post 1505 ^ on day/frame 160 and onwards there's a feature which suddenly appears and stretches from FJL to Alaska, any ideas what that, or it's cause, is?
 added the Ascat 28 days animation.

uniquorn

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Re: The 2018 melting season
« Reply #1516 on: June 21, 2018, 10:01:24 PM »
<snippage>If someone wants to enhance the -1.8 SST in a nullschool screenshot perhaps this would be clearer. Its easiest to see in their SSTA maps.
It looks a lot prettier but I'll let you interpret it.

tech notes:
chose nullschool waves rather than currents - more on topic to recent forum comments
imagej brightness/contrast 11,191 clahe 63,256,2.2

Hyperion

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Re: The 2018 melting season
« Reply #1517 on: June 21, 2018, 10:08:43 PM »
magnamentis, is there any product for measuring cloud cover? I'm loathe to try and eyeball worldview pictures and draw any conclusions.

perhaps a few of the "Pros" know better sources but what i mean, beside the fact that
it applies today as well as each time i was looking in the past 2 weeks, are the ones
linked below.

i hope the link takes you directly to the right page and zoom level

https://www.windy.com/?clouds,66.089,-1.846,3

http://cci-reanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-tcld-topo

as neven said recently somewhere else, it's all about the weather and clouds to my limited understanding are part of that weather.
The situation with clouds and inbound/outbound energy fluxes is far more complicated than what you can tell by eyeballing visible spectrum. I learnt a lot from working with prof emeritus Steven Salter on his cloud brightening proposal back in 13/14 on this matter, and frankly when frivolous goes crowing about no chance of a record year because he sees cloud across most of the basin on worldview he is talking through the proverbial hole that ain't his mouth.  There is only a narrow range of very small liquid water droplet cloud at that has a beneficial effect on radiation fluxes and it must be at least a kilometer up to not be subject to wind waves that are rolling it down on the ice surface. Ice crystal cloud is always bad as it let's in most of the high energy part of the spectrum but blocks outgoing long wave. It may feel cooler to you under ice crystal cloud than a clear sky but you will sunburn just as fast. And bottom melting is likely to be enhanced. Low-level large water droplet cloud like fog or anything even a little gray, also blocks outgoing long wave, and very efficiently absorbs all incoming solar spectra but for a few narrow bands of visible spectrum. If there is any air movement then the droplets and worse liberated vapour transfer the energy to the ice. And the absorbed spectra are reradiated as long wave that half of get down to the surface anyway. So if it is below freezing at 850hpa you can pretty much guarantee there is no cloud beneficial to ice. And any significant air movement near surface ditto. If you compare total atmospheric column total cloud water numbers with total precipital water you will realise that there is far more water as vapour than cloud these days over the Arctic. This is very bad as its latent heat when it condenses and/ or crystallises is enormous. Whether its directly on the ice at altitude where the long wave can deeply penetrate the ice this is very bad. You may not feel the heat of being cooked by microwaves but you are. And you may feel cold in humid or foggy conditions when the air temp is low but above freezing but you are warmer, the ice is colder, so it feels warm.
Regarding Neil repeatedly bringing up solar minimum as beneficial for ice retention. My understanding is that the large number of sunspots and solar storms during minimum with the high flux of very high energy particles striking the upper atmosphere cause it both to down radiate more long wave, and expand increasing its insulation properties, trapping more heat in the lower atmosphere. So not good for ice, but I believe the magnitude of this effect is small less than one percent over a year. But it could be much higher for shorter periods during and after solar events.
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A-Team

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Re: The 2018 melting season
« Reply #1518 on: June 21, 2018, 10:09:36 PM »
Quote
frame 160 and onwards there's a feature which suddenly appears and stretches from FJL to Alaska, any ideas?
If you are talking about the sudden, persistent dark band on Ascat-AB on June 10th (day 162), that appears to have been a squall line (rain) that you can watch transiting across the Arctic from SZ-FJL towards the Bering Strait on GFS nullschool. It had the effect of taking out surface roughness (ie smoothing ice and snow features at the characteristic dimensions that give rise to backscatter at this radar's wavelength).

There's no support for localized melt from a passing swath of warm temperature (ie without rain or associated water vapor) though those did affect, differently in Ascat appearance, a large area south of the dark band on the Siberian side. This was an unusual event as nothing similar has happened since mid-September. MSLP was in sort of a quadrapole configuration centrally at the time, https://tinyurl.com/y9v6sdhb.
« Last Edit: June 22, 2018, 06:31:50 AM by A-Team »

Hyperion

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Re: The 2018 melting season
« Reply #1519 on: June 21, 2018, 10:29:07 PM »
<snippage>If someone wants to enhance the -1.8 SST in a nullschool screenshot perhaps this would be clearer. Its easiest to see in their SSTA maps.
It looks a lot prettier but I'll let you interpret it.

tech notes:
chose nullschool waves rather than currents - more on topic to recent forum comments
imagej brightness/contrast 11,191 clahe 63,256,2.2

I actually ment SST but I'm not sure if there's anything that could be drawn out in their color key anyhow. Thanks though. I'm sure that the better resolution of your image looks much better than my phone screen images. One thing though. I chose a SSTA image from 2 days ago. The melt shown in wipe animation seems to have lowered surface salinity and raised the temp to about -1.7 across the central region, other than these extremities.
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
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Hyperion

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Re: The 2018 melting season
« Reply #1520 on: June 21, 2018, 10:32:09 PM »
Itp 108 has been showing lots of deep mixing for months and a rise in near surface salinity recently.
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
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Frivolousz21

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Re: The 2018 melting season
« Reply #1521 on: June 22, 2018, 05:12:52 AM »
The 12z gfs has a major game changing dipole anomaly in the long range.

It's way out there and will likely change.

But this is the only out come we see even a top 3 finish in lowest extent.


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cesium62

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Re: The 2018 melting season
« Reply #1522 on: June 22, 2018, 07:23:34 AM »
So I've been thinking about the apparent "slowness" of this year's extent behavior, and have come to the conclusion that a lot of it has to do with the Kara Sea.
...
Bottom line - 2018 has a "bank" of 300-400k km2 of extent that it could use to get back in the leading pack.

And it's not just the Kara.  Hudson Bay and Baffin Bay are still holding onto a lot of southern ice.  While those three cul-de-sacs might not heat up as much while the sun is high in the sky, they are also relatively isolated, so the current lack of heat in the cul-de-sacs shouldn't greatly influence the melt further north.

While the Pacific side might not be warming up as fast from the sun as in some years (the southern Beaufort, Chukchi, and ESS), the Atlantic side and Laptev has plenty of "momentum".

Certainly the Slater probabilistic prediction has 2018 with a bit higher extent than other recent years through early August, but 2018 is still well positioned to have a lower minimum extent than 2016 and 2007, especially if a hole opens up in the north Chukchi by the middle of August.

oren

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Re: The 2018 melting season
« Reply #1523 on: June 22, 2018, 08:33:39 AM »
Indeed both Baffin and Hudson are on the high-ish side of things, though bear in mind both have not had a downward trend since a phase change 15-20 years ago. Baffin is 170k/200k above 2016/2012, and Hudson is 60k/220k above the same years. In September both will reduce to near-zero.
OTOH, it doesn't mean this will be an especially low year. This year's advantage in the CAB is in a peculiar area (off-Svalbard) which does not have the same characteristics as the proper CAB. All it means is that the race is still open despite what appears to be an apparent slowdown. And viewers would do well to track Wipneus' great chart which provides all data relevant to the min (excepting CAA) and removes all the noise.

subgeometer

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Re: The 2018 melting season
« Reply #1524 on: June 22, 2018, 09:32:53 AM »
magnamentis, is there any product for measuring cloud cover? I'm loathe to try and eyeball worldview pictures and draw any conclusions.

perhaps a few of the "Pros" know better sources but what i mean, beside the fact that
it applies today as well as each time i was looking in the past 2 weeks, are the ones
linked below.

i hope the link takes you directly to the right page and zoom level

https://www.windy.com/?clouds,66.089,-1.846,3

http://cci-reanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-tcld-topo

as neven said recently somewhere else, it's all about the weather and clouds to my limited understanding are part of that weather.

Clouds are not all equal, some are thick blankets, than exclude the sun, and others thin wisps that maybe more effective in trapping the solarenergy that gets in .  WindyTV shows all sorts of cloud parameters, they are complicated things

The CAB has been obscured by thick cloud, which I think would restrict melt in that region. The Beaufort has also been cloudy over recent weeks, but you can still often see the ice dispersing through it, so I doubt those clouds have been as effective in stopping insolation.  I've included a gif of the 'cloudy' Beaufort over the past 10 days

Frivolousz21

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Re: The 2018 melting season
« Reply #1525 on: June 22, 2018, 10:32:35 AM »
The 00z gfs and euro...


Both show ridging slowly building the next 5 days over the central Arctic.

The Beaufort and poleward Atlantic side warm up the quickest.

Expect sunnier conditions to spreadout over the Arctic the next week.

After day 5 the gfs continues to show a dipole anomaly. 

Then the gfs in clown range around day 10-11 brings theoretically possibly the warmest intrusion of contenential air we have ever seen right through the central basin.

The euro is slower to build the dipole but does towards next weekend.

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a Desert Eagle that I call Big Pun
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my TEC 9 Imma call T-Pain
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subgeometer

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Re: The 2018 melting season
« Reply #1526 on: June 22, 2018, 10:40:47 AM »
Grey and blue darkening the ice everywhere on the Russian side now. There are particularly deep blues on coastal ice in the northern/eastern Kara sea and Laptev.

The ice front keeps coming back to a remarkably steady smooth line(eg at about 82.3N north of eastern Svalbard)

Neven

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Re: The 2018 melting season
« Reply #1527 on: June 22, 2018, 12:49:42 PM »
Expect sunnier conditions to spreadout over the Arctic the next week.

That's right. ECMWF still has high pressure creeping over the Beaufort, connecting all the way to the Kara, and then a low pressure area hanging over the Pole. Not a classic dipole, but one nonetheless that is bound to open the Laptev gap wider. Still, it's the sunshine that counts most.
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johnm33

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Re: The 2018 melting season
« Reply #1528 on: June 22, 2018, 02:30:40 PM »
Thanks A-team, that thing persisted for about 18 3hr. periods on nullschool.
Subgeometer Thats more or less where the waves meet the continental shelf and dissipate.

Shared Humanity

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Re: The 2018 melting season
« Reply #1529 on: June 22, 2018, 02:32:45 PM »
Clouds are not all equal, some are thick blankets, than exclude the sun, and others thin wisps that maybe more effective in trapping the solarenergy that gets in .  WindyTV shows all sorts of cloud parameters, they are complicated things

The CAB has been obscured by thick cloud, which I think would restrict melt in that region. The Beaufort has also been cloudy over recent weeks, but you can still often see the ice dispersing through it, so I doubt those clouds have been as effective in stopping insolation.  I've included a gif of the 'cloudy' Beaufort over the past 10 days

All other things being equal, a cloudy Arctic in May, June and July will retard melt and the season so far has been very cloudy. If this continues for a few more weeks, we should not be surprised to see a relatively high minimum.

RoxTheGeologist

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Re: The 2018 melting season
« Reply #1530 on: June 22, 2018, 05:16:19 PM »

All other things being equal, a cloudy Arctic in May, June and July will retard melt and the season so far has been very cloudy. If this continues for a few more weeks, we should not be surprised to see a relatively high minimum.

Yes, and I think we shouldn't underestimate the effect of snow fall on the Arctic in the summer. Even a thin layer of snow will have a strong effect. It may not provide much insulation but it dramatically increases the albedo. Bare ice absorbs 5x the amount of energy from sunlight that snow will absorb.

 https://nsidc.org/cryosphere/seaice/processes/albedo.html.


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Re: The 2018 melting season
« Reply #1531 on: June 22, 2018, 05:45:28 PM »


... If this continues for a few more weeks, we should not be surprised to see a relatively high minimum.

I would be very much surprised to see a high minimum. As per Wipneus' wonderful graphs the CAB is well on its way to new lows. And since everything else (well, mostly, these days) melts out anyway, why would there NOT be a new minimum?

I do know that it is a chaotic system, so forecasts are almost impossible even for 2-3 months ahead, but on the graphs I see that it is mostly the Kara and Hudson that distort the total numbers - and they do not matter much...

A-Team

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Re: The 2018 melting season
« Reply #1532 on: June 22, 2018, 06:06:47 PM »
Quote
The ice front keeps coming back to a remarkably steady smooth line about 82.3N north of eastern Svalbard
The record ice retreat north of Svalbard does not correlate with bathymetric boundaries, notably with neither Yermak Plateau nor Barents continental shelf. The edge positions of open water and floey ice result from a variable combination of wind, warm air temperatures, eastern surface currents and effects from incoming Atlantic Waters (normally at ~300m depth). Winds have not contributing decisively to drift over the last five days.

Technical note: the second gif deepens contrast of pure white (solid ice) on each AMSR2 date by saving an effective setting in gimp and applying it consistently to the co-registered bathymetric layer (which required a -45º rotation). The Svalbard data would benefit from an inset map showing exactly what region is being measured. The two-day Osi-Saf drift vectors are 3x their actual length; purple indicates guesswork rather than measured feature displacement.

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« Last Edit: June 22, 2018, 06:44:56 PM by A-Team »

RoxTheGeologist

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Re: The 2018 melting season
« Reply #1533 on: June 22, 2018, 06:33:22 PM »
Quote
The ice front keeps coming back to a remarkably steady smooth line about 82.3N north of eastern Svalbard
The record ice retreat north of Svalbard does not correlate with bathymetric boundaries, notably with neither Yermak Plateau nor Barents continental shelf. The edge positions of open water and floey ice result from a variable combination of wind, warm air temperatures, eastern surface currents and effects from incoming Atlantic Waters (normally at ~300m depth).


That's really interesting! From what I have read the pycnocline is usually dominated by salinity changes. As soon as you get to continental shelf the denser Atlantic waters 'should' be sinking down below the fresher but colder surface waters. Does this imply that the Arctics protective freshwater lens is fraying at the edges?

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Re: The 2018 melting season
« Reply #1534 on: June 22, 2018, 07:12:33 PM »
Quote
Does this imply that the Arctics protective freshwater lens is fraying at the edges?
The Mercator Ocean site is probably the best place to pursue that idea. It presumably folds in the vast observational literature for this region. The last 60 days has seen a lot of interesting papers posted at The Cryosphere' but nothing specific to this, ditto GoogScholar.

The July 1st forecast of ocean temperature is also an ice edge forecast; nothing dramatic is foreseen.

http://bulletin.mercator-ocean.fr/en/PSY4#4/59.04/-58.32

https://www.the-cryosphere.net/recent_papers.html

Quote
snow fall on the Arctic in the summer? Even a thin layer of snow dramatically increases the albedo.
There's a very readable March 2018 paper on the whole snow business:

A Distributed Snow-Evolution Model for Sea-Ice Applications(SnowModel)
GE Liston et al
https://doi.org/10.1002/2017JC013706

"Snow-depth distributions on sea ice have substantial impacts on winter ice growth and summer ice melt. There are two types of wind-related snow distributions in this environment: snowdrifts that form around ice pressure ridges; and snow dunes and other snow bedforms that form on relatively level, undeformed ice.  A snow-evolution modeling system was tested against winter snow observations collected during the Norwegian young sea ICE expedition north of Svalbard.

Snow covering Arctic sea ice plays critical roles in sea-ice evolution and numerous other Arctic climate related processes. This snow is an effective insulator that strongly governs heat transfers through the ice. In addition, the spatial distribution of snow properties and depths plays a large role in controlling energy exchanges and winter ice growth. An uneven snow thickness distribution, which occurs when snow is blown into drifts and dunes, allows more heat loss than would occur if the same volume of snow were uniformly distributed on the ice surface, resulting in enhanced winter ice growth.

Summer albedo and snow and ice melt is often governed by melt pond formation and total pond area on the ice surface, and these distributions are strongly tied to the previous winter’s snow redistribution. In addition, relatively small-scale snow surface features control aerodynamic surface roughness and the associated turbulent energy transfers at the snow-atmosphere interface. Through these impacts on turbulent fluxes, heat conduction, and melt pond formation, minor changes to snow distribution have major impacts on ice mass balance and must be considered in any effort to evaluate local and regional energy balances and fluxes.

Unfortunately, Arctic snow-depth observations on sea ice are limited. Using snow depths and densities measured over level and deformed multiyear sea ice (MYI) at Soviet drifting stations, Warren et al. (1999) provided the most comprehensive analysis of Arctic Ocean snow depths currently available. However, that climatology was developed using data collected between 1954 and 1991 and was from a limited number of stations.

Recent snow and ice field measurements have shifted from MYI to relatively new ice, because the predominant ice types have become younger over much of the Arctic. Both observations and models indicate a reduction in mean snow depth associated with the transition from MYI to first year sea ice). In addition to the transition to younger ice, changing seasonality, particularly the observed later onset of ice freeze up and snow accumulation, will likely impact total snow accumulation, snow distributions, and snow evolution on sea ice.

When seasonal sea ice is thinner than MYI, it is typically more sensitive to snow accumulations in several ways. First, snow has a thermal conductivity approximately an order of magnitude lower than sea ice. When sea-ice cover is thin, the thermal resistance of the snow cover becomes an increasingly dominant control over winter ocean-atmosphere conductive heat fluxes, and hence ice growth .

Second, since the buoyancy force of thin ice is not as large as thicker ice, snow can more easily depress the ice surface below sea level, resulting in surface flooding and snow-ice formation. Third, the albedo of bare FYI is approximately 0.1–0.15 lower than bare MYI, while the albedo of optically thick (~10 cm) snow covering FYI and MYI is the same.

Therefore, the energy balance impact of retaining an optically thick snowpack on top of FYI is greater. Finally, recent work indicates that freshwater from snowmelt may impose important controls on FYI melt pond formation, and earlier work indicates that snow distributions on sea-ice control melt pond location and morphology."

https://www.researchgate.net/publication/323968261_A_Distributed_Snow_Evolution_Model_for_Sea_Ice_Applications_SnowModel
« Last Edit: June 22, 2018, 07:32:53 PM by A-Team »

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Re: The 2018 melting season
« Reply #1535 on: June 22, 2018, 07:14:38 PM »
Quote
Does this imply that the Arctics protective freshwater lens is fraying at the edges?
The Mercator Ocean site is probably the best place to pursue that idea. It presumably folds in the vast observational literature for this region. The last 60 days has seen a lot of interesting papers posted at The Cryosphere' but nothing specific to this, ditto GoogScholar.

The July 1st forecast of ocean temperature is also an ice edge forecast; nothing dramatic is foreseen.

http://bulletin.mercator-ocean.fr/en/PSY4#4/59.04/-58.32

https://www.the-cryosphere.net/recent_papers.html
Those Mercator maps are garbage.

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Re: The 2018 melting season
« Reply #1536 on: June 22, 2018, 07:17:40 PM »
Copernicus is fantastic. Norwegia's petrodollars go much farther than whatever France extracts from their cheese exports.


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Re: The 2018 melting season
« Reply #1537 on: June 22, 2018, 07:37:16 PM »
Careful there, from the fine print it appears that the Copernicus and Mercator Ocean sites are both using similar models and data sets from OSI-SAF. Mercator has a much better interface and display than the broken-feature Copernicus. Both wander off-science into marketing applications.

If there are significant differences, you would have to locate and drill into the netCDFs of both and prepare comparison maps for us in Panoply, then look at what can be directly observed from daily satellite images to determine actual accuracy of either, both or neither.

Sea surface temperatures (#1534) are the easy part. Underwater? Nobody has been retrieving mooring data the last ten months; those plus CTD casts sample very sparsely in space and time. While this area has been studied very intensively from shipboard, what is going on today (and in near-term forecasts) remains to be determined.
« Last Edit: June 22, 2018, 07:56:44 PM by A-Team »

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Re: The 2018 melting season
« Reply #1538 on: June 22, 2018, 08:21:40 PM »
Yes, be careful there folks. Notice that the two images above of SSTs in the Barents sea don't have the same baseline. It may have warmed more than you think it did.

All of these models of the Arctic are limited by the need for more and better data. The Mercator models are science based, but without better coverage of the Arctic ocean by buoys the model maps could have some large deviations from reality. We'll never know better without better data coverage.

Interpreting oceanographic maps is not simple. They are useful but they are easily misinterpreted. I have been looking at them and reading papers about oceanography for years, but self-education is not easy even for someone trained in a related scientific discipline. I have made interpretation errors in the past.

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Re: The 2018 melting season
« Reply #1539 on: June 22, 2018, 09:24:56 PM »
Someone noted above that the graph of Wipneus which restricts to the 7.1 kkm2 Arctic Basin is probably the best way to track the melt season and compare to earlier years and methods. (Note it isn't suitable for monitoring overall loss of NH planetary heat reflector because decline in permafrost land albedo also contributes.)

Below, I made a rough effort to add a percent scale to the right side as that seems more relevant to degree of 'blue ocean' attainment than sq km numbers. On average, there is 67% extent over the May 1st to Sept 15th insolation season so we are something like a third of the way there already in years like 2012.

This could have been weighted by TOA insolation which of course is less by September when open water is more. Then an imponderable cloud correction would be needed as not all the sunlight reaches the ice and not all the insolation reflected from the ice escapes back to space as the undersides of the clouds send some of that back down. So the one-third of 'blue ocean already' might be too high but one-fifth might be about right (details left to other posters).

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Re: The 2018 melting season
« Reply #1540 on: June 22, 2018, 09:42:08 PM »
Meanwhile, a weather forecast.

For the last week or so lows from the Atlantic have not been blocked so the UK and NW Europe have had cool westerlies.

But now a big fat blocking high is developing over the British Isles, sending Atlantic weather up twixt Greenland and Scandinavia. The UK met office are saying this high is here for the next two weeks at least, and a shift in the jet steam is the culprit. A fairly substantial low is coming in and should reach Svalbard on Wednesday (27 June) and sort of peter out close to the North Pole at the weekend.

Maybe we will see a bit of Fram Strait ice export next week?
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Re: The 2018 melting season
« Reply #1541 on: June 22, 2018, 09:50:36 PM »
Yes, be careful there folks. Notice that the two images above of SSTs in the Barents sea don't have the same baseline. It may have warmed more than you think it did.

Yes, I find changing colour keys on maps of things like temperature and salinity Intensely irritating. I even found nullschool was doing it when I wrote a pixel counting program to try and track sea level pressure changes over the Arctic basin. No where near as bad as the Itp buoy charts, where the key is different for different buoys and even shallow and deep charts on the same image. That Mercator one takes the prize. This sort of thing can only be regarded as deliberate misinformation and misdirection. Makes me want to try and recolour and rekey and republish all their charts. But it also damages my confidence in their models to the point where I won't bother. In a world where 12 year old kids are putting rPis and satellite telemetry and control transceivers in solar powered model boats to complete with each other in ocean crossings, why does it cost a million bucks for self powering wave glider submersibles that could autonomously map salinity, temp, currents etc and be launched at any convenient beach. The parts cost would be a few hundred dollars. With the hotter water at depth in the Arctic you don't even need waves to power them. A skin with a suitable low melting point wax molded into it would make transition from glide down to glide up mode and back automatic. A cheap cellphone has all the electronics you need for comms Navigation, data processing. I don't believe finding leads to transmit their data from would be a difficult programming job.

Meanwhile the North Atlantic warm blob and Gulfstream definitely seem to be surging north into the North sea. The prolific outflow from the Labrador sea, seem to be getting forced north too, so it will have plenty of opportunity to mingle with, freshen, and make more buoyant the massive incoming energy in the stormy shallows near the faroes. Big heat is knocking at the Chukchi gate from the Pacific also.
The mixing at both ends spells big danger for the halocline as the salinity at surface and 50-200m become similar.
« Last Edit: June 23, 2018, 01:20:00 AM by Hyperion »
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Hyperion

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Re: The 2018 melting season
« Reply #1542 on: June 23, 2018, 01:43:34 AM »
The -1.8C anomalously cold SST regions are back, extending across from the new Siberian islands to Elsmere island and also Chukchi to inner CAA on the Pacific side, seeming to correspond with where outflow plumes from the Beaufort gyre, entraining Atlantic, and Pacific inflows. Except for a spot of warmer than normal sst, that may be the energy overcoming the ices resistance or the main fresher outflow current.

Lathing away its deep circulation on the Chukchi plateau and transferring momentum to the warm salty inflows its sucking, this is a gyre in deep trouble. This setup of suction, reaction mass and shallow and highly textured bottom bathometry will likely keep it rammed up against the Chukchi shallows and shredding itself and the Amerasian basin halocline. The Atlantic side halocline looks in even worse shape. Right out to the North pole extending to the Lomonsov ridge its -1.8C SST, corresponding to at least 33psu surface salinity within the pack.
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Re: The 2018 melting season
« Reply #1543 on: June 23, 2018, 03:53:15 AM »
Mercator gives you the option of a fixed baseline. Mercator is NOT the worst about this.
Use the fixed colorbar option.

Don't click "Download".
Click "Download (fixed colorbar)".

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Re: The 2018 melting season
« Reply #1544 on: June 23, 2018, 04:04:09 AM »
Expect sunnier conditions to spreadout over the Arctic the next week.

That's right. ECMWF still has high pressure creeping over the Beaufort, connecting all the way to the Kara, and then a low pressure area hanging over the Pole. Not a classic dipole, but one nonetheless that is bound to open the Laptev gap wider. Still, it's the sunshine that counts most.

The 12z euro, gfs, and gem are all in agreement to bring a partial dipole anomaly after day 5.

Tho not to also dismiss that warming will already be underway by this time tomorrow with warm are being pumped in from Alaska and Western Russia.

After day 5 the sole warmth comes from a large Western CAB ridge.

The gfs keeps showing an epic land to ice pulse of record heat.


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bbr2314

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Re: The 2018 melting season
« Reply #1545 on: June 23, 2018, 04:53:03 AM »
The land-to-ice pulse has already been record-setting. The heat has been slightly less widespread but more focused than 2012.

This has led to the anomalous situation where the high latitude ice is actually worse than any other year by a wide mile (IMO), but the snow extent residuals have held up Hudson Bay and Kara, UNLIKE 2012 where those areas were the first regions to melt out.

This change has resulted in lower continental temperatures but increased efficiency of oceanic heat distribution as higher albedos overwhelm all other factors when it comes to energy input / output, allowing the atmosphere to balance the ever-increasing heat load with higher positive AND negative departures.

Residual 500MB anomalies / blocking due to the albedo situation has turned the continental heat cannons into overdrive since 2012, so while the distribution of anomalies has become alarmingly different, their new organization is a visible and natural evolution and not some kind of black swan event.

While the NHEM's efficiency of resolving +GHG heat anomalies has increased due to the albedo anomalies of both Greenland and the mid-high continental latitudes, this has come at the expense of the failing Arctic Ocean cryosphere, which bears more direct / continuous oceanic heat burden under the increasingly +GHG regime.

Copernicus is interesting in its 7/1 area % forecast as it shows the "division" between the Siberian and CAA packs gaining increasing momentum. It seems that as the Atlantic-side ice melts away from the Arctic islands entirely, the loss of tension will allow the pack to truly begin to cleave between the Siberian and Canadian sides, with millions of square KM of poorly formed FYI making up the "glue" in the middle set to melt out entirely by 8/1.

Call me crazy but checking EOSDIS, 2018 is only a few days of melt away from 2012 appearance wise in terms of coherency. But the amount of open water is already much higher. This additional momentum will give 2018 an even larger boost than the situation year to date. July is going to be horrific IMO.

bbr2314

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Re: The 2018 melting season
« Reply #1546 on: June 23, 2018, 05:06:14 AM »
Here is open ocean with 2016's albedo map overlaid with areas open in 2018 (expected as of 7/1). Blue is where we have more ice this year. The difference will be absurd in the Highest Arctic and the residual accumulations of insolation will mean the CAB is hit harder than ever this summer.

The thickness maps are worse. Could this be the year we lose the CAB almost entirely?

« Last Edit: June 23, 2018, 05:14:08 AM by bbr2314 »

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Re: The 2018 melting season
« Reply #1547 on: June 23, 2018, 06:19:47 AM »
the CAB is hit harder than ever this summer.

The thickness maps are worse. Could this be the year we lose the CAB almost entirely?


Jeez man, looks like bar a few bergs calved from Greenland, Outer CAA, and Svalbard, we'll be lucky if we don't lose the whole lot.
Look at the SMOS from the 21st. Its like between the Atlantic inflows towards the Pole north of Svalbard, and towards nares from the ESAS, and the Pacific inflow over the Chukchi to inner CAA, and those outflows into the inner Beaufort, and nares region. The packs being carved into five separate chunks.
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Re: The 2018 melting season
« Reply #1548 on: June 23, 2018, 06:30:43 AM »
The ARCUS SIPN report is out for predictions of Sept SIE based on May data :

https://www.arcus.org/sipn/sea-ice-outlook/2018/june

Median projection this year is 4.6 M km2.
Incidentally, that is pretty close to my estimate of 4.65 M km2 which was based on the Northern Hemisphere albedo (snow cover, ice 'area' and 'extent') in the report.

« Last Edit: June 23, 2018, 06:44:03 AM by Rob Dekker »
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Re: The 2018 melting season
« Reply #1549 on: June 23, 2018, 07:20:48 AM »
The ARCUS SIPN report is out for predictions of Sept SIE based on May data :

Median projection this year is 4.6 M km2.
Incidentally, that is pretty close to my estimate of 4.65 M km2 which was based on the Northern Hemisphere albedo (snow cover, ice 'area' and 'extent') in the report.


What about Volume? It won't mean any good if we have a - 2 SD Extent made up of Slush floating around.