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Frivolousz21

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Re: The 2018 melting season
« Reply #1250 on: June 13, 2018, 07:28:13 AM »
Looks like smos is being tricked by water on the ice surface from recent melting
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Aluminium

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Re: The 2018 melting season
« Reply #1251 on: June 13, 2018, 09:30:32 AM »
June 8-12.

Avalonian

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Re: The 2018 melting season
« Reply #1252 on: June 13, 2018, 09:45:29 AM »
Some striking developments there, Aluminium. Interesting crack developing between Laptev and eastern Siberia, apparent open water suddenly appeared in the CAA (southern passages; still cloudy on Worldview); and if it's correct rather than fooled by surface water, then surely the big drops in Kara and Laptev are but days away.

deconstruct

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Re: The 2018 melting season
« Reply #1253 on: June 13, 2018, 09:51:19 AM »
Thank you, seems like it is only a couple years away..




You can't extrapolate the trend like this.
There are some feedbacks, that can move the time when the Arctic is ice free further to the future. One thing - and we seen that IMO in the recent years -  is, that as the Arctic loses more and more ice and gets warmer, there is much more open water and therefore much more evaporation. And that evaporation occurs in fall as snow, so it could be, that we see much higher winter precipitation and snowpack on the ice as well as on the surrounding land area. And that snow protects the ice below by increasing albedo, by insulating it and by the need to melt the snow first to expose the ice below.

When you compare e.g. current snow coverage in the Arctic to previous years, this year is (as is last year) on the higher end. All years that had record or very low ice area recently (like 2007, 2012, 2016) all had a much below average snow-coverage.

Look e.g. at that chart
https://www.ncdc.noaa.gov/snow-and-ice/extent/snow-cover/nhland/4

My guess is, that this year will therefore not set any new record or play in the same ballpark as 2012 or even 2016. Even despite the heat on the Siberian side, there is still much more snow there, than e.g. in 2012. So it takes a lot of heat (and time), to melt all that snow first, and thus the period for real ice melt is shorter this year for much of the Arctic. And on the Canadian side there is even more snow left, as it was much cooler till now. Just compare e.g. that image from the CAA from 2012 to 2018:

aperson

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Re: The 2018 melting season
« Reply #1254 on: June 13, 2018, 10:01:46 AM »
...

Excellent points about snow. It's important to remember that fresh snow has an albedo of around 0.9 while ice has an albedo around 0.5.

I think the best way to start attacking snow-covered ice is with warm air advection that's sufficiently moist to reach the surface layer. Once this lowers albedo, insolation and clear skies from the resulting inversion layer are several times more effective.

SMOS also doesn't handle melt-ponding correctly. It's clear if you look at satellite imagery. I would recommend looking at something like HYCOM thickness instead.


(https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/arctic.html)

oren

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Re: The 2018 melting season
« Reply #1255 on: June 13, 2018, 10:02:21 AM »
June 8-12.
I think this shows very nicely the export of ice on the Pacific and Atlantic fronts over the past few days, and also how the ice edge in those regions is already losing its shape. Extent has stalled, but in the medium term this is bad for ice retention - best to stay on the defensive in a cool place than march offensively to a killing ground of warm water for a temporary advantage.
OTOH, the deep blue areas in Laptev and ESS are water on ice, and could make a comeback before final collapse.

Pagophilus

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Re: The 2018 melting season
« Reply #1256 on: June 13, 2018, 12:58:47 PM »
To back up your point here is a contrast-altered image from Worldview this morning.  It shows, in my view, floes pouring out of the north/east Kara sea into the Barents, and then backing up extensively once they hit Franz Josef Land, where their density once more increases.  AMSR2 distribution for today is consistent with this, and consistent with plummeting ice density in the north Kara.  So the Kara may be emptying of ice faster than it is melting right now.

Extent could well continue to increase while this happens.

The floes eventually slide around to the S of FJL.  The front of this tongue of extruding ice (S and W of FJL) has been frustratingly mostly under cloud for several days now.  Glimpses between the clouds have hinted at large areas of melting tendrils of ice, but it is very hard to be sure.  As you imply, it is a one way trip -- just a matter of time.

Original unaltered worldview image also attached for reference.     
I think this shows very nicely the export of ice on the Pacific and Atlantic fronts over the past few days, and also how the ice edge in those regions is already losing its shape. Extent has stalled, but in the medium term this is bad for ice retention - best to stay on the defensive in a cool place than march offensively to a killing ground of warm water for a temporary advantage.
OTOH, the deep blue areas in Laptev and ESS are water on ice, and could make a comeback before final collapse.

Alexander555

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Re: The 2018 melting season
« Reply #1257 on: June 13, 2018, 01:03:10 PM »
How reliable is that information ? That's a few million km2 that lost 30 to 40 cm of ice in just 10 days. I never did any calculations about how much heat it takes to melt an amount of ice. But it looks plenty.

Pagophilus

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Re: The 2018 melting season
« Reply #1258 on: June 13, 2018, 01:16:32 PM »
Rapid spreading of blue ice areas in ESS.  Towards the west of the first area spotted yesterday.

Second image with color saturation pumped +50 on Photoshop
« Last Edit: June 13, 2018, 01:25:31 PM by Pagophilus »

Pagophilus

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Re: The 2018 melting season
« Reply #1259 on: June 13, 2018, 01:19:36 PM »
That was my question as well.  aperson above states "SMOS also doesn't handle melt-ponding correctly. It's clear if you look at satellite imagery. I would recommend looking at something like HYCOM thickness instead."   So I am going to do that.  It fits a lot better with the observed reality. And hugely reduces concerns of a rapid Arctic meltout.

 
How reliable is that information ? That's a few million km2 that lost 30 to 40 cm of ice in just 10 days. I never did any calculations about how much heat it takes to melt an amount of ice. But it looks plenty.

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Re: The 2018 melting season
« Reply #1260 on: June 13, 2018, 01:34:56 PM »
this morning when i was looking at : https://ads.nipr.ac.jp/vishop/#/extent

i first was annoyed but then had to laugh loudly because it's a good day as far as once again the value of extent numbers at this time of the year has been negatively proven:

a) almost the entire arctic is aroun or above zero

b) parts of the ice cover are hit with temps way above melting temps and in places above 30C

c) ice is thin and mobile and the winter was warm

d) there have been extraordinarily strong winds recently and rain throwing water on the surface.

and now the models want to make us believe that zero ice has been melting yesterday ?

a big joke is the only non-offensive word that comes to my mind, and no wonder that some
question the expenses (i'm not but some are) it's similarly ridiculous like the millions of euros expensive weather forecasts in times when skies are neither blue or overcast and it's not that easy ;)

this is probably due to the 15% threshold which each year causes issues, perhaps we better start to count only zero or close to zero ice agains non-totally ice free to avoid such ups and downs, both often not justified.

where does the 15% threshold come from, is it arbitrary or does it have a solid foundation?

the above mentioned measuring of blue against white or anything that is not totally blue/black i mean seriously being an alternative to those complicated and at times contradictory algorithms that fail over and over again and each failure is feeding deniers who can point at such ridiculous numbers to "QUASI" make their point and cut funding.

i'm sure that some won't like this but this is my opinion and it's about seeking maximum accuracy and clarity as opposed to complicated and well paid models that so often can't keep up with their promises.

those who have another opinion are welcome to tell me why, i'm listening, this is not meant to be the only valid opinion, hence convince me where i'm wrong in your opinion but with reason, not with bias or trouble to get out of the comfort zone ;)

finally it is a miracle that they (the models) don't try to tell us that there was more freezing than melt LOL  ???
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Alexander555

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Re: The 2018 melting season
« Reply #1261 on: June 13, 2018, 02:27:37 PM »
As far as i see it, the models are not telling that no ice melted. The models are telling that plenty of ice melted. Only that area on the siberian side lost maybe 500 km3 in the last 10 days. If the graphs are right.

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Re: The 2018 melting season
« Reply #1262 on: June 13, 2018, 03:35:30 PM »
Someone did enquire over the use of 15% cut off and the reply , if I remember correctly, was that the measure evolved to deal with peripheral ice?

At that time the only fragmented ice was generally around the edges of the pack with contiguous ice cover in the centre.

We are now at a time that the whole pack is fragmented and held together by thin , late formed 'glue ice'. When we hit melt season proper then this glue ice goes away and we end up with a very mobile pack and open water between floes.

In the denser populated areas we are well over the 15% cut off but ,as the season progresses those areas still sit at full ice even when well below 50% cover!

The past couple of years finishes may have been pretty mangled by the measure meaning we could be celebrating 4th or 5th lowest as a sign of sea ice losses stabilising when the reality in the water is very different?

When we hear the " when the ice goes it will go pretty fast" we might bear the 15% cut off in mind!

EDIT: So the reality exists that each grid square could hold its 16% ice cover ,across the whole basin, and our measured extent would tell us we have a solid iced basin???? How can this be seen as an effective measure now the pack is so altered?
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dosibl

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Re: The 2018 melting season
« Reply #1263 on: June 13, 2018, 04:14:50 PM »
My understanding of 15% for extent is that it was picked for navigation vs being indicative of the ice  in general, its continued use is because extent data is our oldest dataset so it affords us better historical comparison.

oren

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Re: The 2018 melting season
« Reply #1264 on: June 13, 2018, 04:23:52 PM »
Magna, for accuracy's sake please remember the definition of extent and how it is reported. First, extent does not tell you how much melt occurred, not directly. Area is a better approximation of melt and has actually gone down in the last few days, but really only volume tells you about actual melt. But volume is not measured, only reported by a model (PIOMAS) twice per month. In principle, the whole arctic could drop from 1m thickness to 20cm thickness without any change in extent. Only ice that has lost the last few cm to become actual water is supposed to affect the area numbers, and indirectly the extent numbers. So don't confuse extent with melt.
In addition, extent is not a model, but a measurement done by satellite. Take a look yourself in Worldview at those regions where the satellites report higher extent, and see the ice for yourself. The explanation for the weird extent numbers is dispersion. Ice that was at e.g. 100% concentration shifted to 80% concentration but over a larger region.

seaice.de

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Re: The 2018 melting season
« Reply #1265 on: June 13, 2018, 04:59:19 PM »
How reliable is that information ?

Not reliable at all!

SMOS sea ice thickness is only reliable when its cold. The penetration depth decreases when the ice is getting warm. Therefore UH stops delivering Arctic sea ice thickness products in April and starts only in October.

Look at figure 6 in https://www.the-cryosphere.net/8/997/2014/tc-8-997-2014.pdf

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Re: The 2018 melting season
« Reply #1266 on: June 13, 2018, 06:36:52 PM »
My understanding of 15% for extent is that it was picked for navigation vs being indicative of the ice  in general, its continued use is because extent data is our oldest dataset so it affords us better historical comparison.
My understanding matches dosibl's (where 15% came from and why we continue to use it).  SIE numbers were never intended to make anybody believe we had that much 'completely iced over' expanses.
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Re: The 2018 melting season
« Reply #1267 on: June 13, 2018, 06:43:12 PM »
Quote
Arctic Ocean ice is deeply covered by snow and an increasing future snowpack will arrest climate change.
Folks, the time has come to stop talking about imaginary fluffy spring snowpacks and speculating about snowfall in the distant future. It is ankle-deep at best today and only got to mid-calf at the peak of winter in the CAB. The Siberian third has no snow cover at all and has been like that for quite a while. The ice surface off the eastern ESAS is filthy and has been that way for weeks.

https://www.esrl.noaa.gov/psd/forecasts/seaice/
hs in RASM-ESRL_4UAF_ICE_2018-06-12_00001

Quote
UB SMOS confuses melt ponds with ice thickness
It overlays thinness and melt ponds in the sense of just measuring dielectric, so actually is is a melt pond resource (from June 5th on) provided these can be disambiguated (say with ESRL or Hycom thickness) and from transient weather artifacts. Note ESRL provides a daily melt pond fraction estimate and seven-day forecast.

Recent rain and melt have altered the Ascat roughness landscape. As the weather system passes however, new persistent markers have emerged. The 43 day mp4 below interleaves images from the A and B instruments to assess this. The thin black (smoothed) veined swath that extends from Utqiaġvik (Barrow) across the entire Arctic Ocean to FJL has no counterpart in the visible, infrared or shorter wavelength radar. While it does continue previous long-term tracking features, this would be a huge challenge to pick up with AI.

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Re: The 2018 melting season
« Reply #1268 on: June 13, 2018, 06:46:09 PM »
My understanding of 15% for extent is that it was picked for navigation vs being indicative of the ice  in general, its continued use is because extent data is our oldest dataset so it affords us better historical comparison.
My understanding matches dosibl's (where 15% came from and why we continue to use it).  SIE numbers were never intended to make anybody believe we had that much 'completely iced over' expanses.
That, and the numbers are much more consistent than any other metric. 

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Re: The 2018 melting season
« Reply #1269 on: June 13, 2018, 06:56:26 PM »
My understanding of 15% for extent is that it was picked for navigation vs being indicative of the ice  in general, its continued use is because extent data is our oldest dataset so it affords us better historical comparison.
My understanding matches dosibl's (where 15% came from and why we continue to use it).  SIE numbers were never intended to make anybody believe we had that much 'completely iced over' expanses.
That, and the numbers are much more consistent than any other metric.
This has to do with the typical margin of error being around 15% at low ice concentration. i.e. 15% is about the point at which you can be reasonably sure you are measuring some ice.

FishOutofWater

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Re: The 2018 melting season
« Reply #1270 on: June 13, 2018, 07:09:30 PM »
The exact details of the metrics are not important unless you are in a boat trying to avoid sea ice. What's important is how the ocean/ice/atmosphere/biosphere system is changing as GHGs add planetary heat. We are arguing over fine details about sea ice extent that are insignificant to the big picture. The amazing Greenland vortex we have seen this late spring is a very anomalous feature which our discussion is ignoring while we argue over details about extent and area that will be wiped out in a few weeks time.

The 90 pattern of winds and currents has been very efficiently transporting cold water into the Labrador sea, followed by deep convection as it mixes with warm Gulf stream water. This weather/current pattern is speeding up the rate of transport of Gulf Stream water across the temperate north Atlantic then up the coast of Norway. There has been a stunning anomalous amount of northwards heat transport in the north Atlantic over the past 90 days that will affect the Arctic for many months.

marcel_g

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Re: The 2018 melting season
« Reply #1271 on: June 13, 2018, 08:09:23 PM »
The amazing Greenland vortex we have seen this late spring is a very anomalous feature which our discussion is ignoring while we argue over details about extent and area that will be wiped out in a few weeks time.

The 90 pattern of winds and currents has been very efficiently transporting cold water into the Labrador sea, followed by deep convection as it mixes with warm Gulf stream water. This weather/current pattern is speeding up the rate of transport of Gulf Stream water across the temperate north Atlantic then up the coast of Norway. There has been a stunning anomalous amount of northwards heat transport in the north Atlantic over the past 90 days that will affect the Arctic for many months.

How do you think this north Atlantic heat transport will affect the ice on the Atlantic side? I'm asking because I don't really know what the mechanisms are for affecting the ice.

Will there be storms that bring warmth and waves to melt the ice back into the CAB? Or will the warm water currents melt ice until they hit the bathometric drop offs and then sink too low to melt ice any further into the CAB?

Or will there be ice retention in the CAB because the winds are no longer exporting ice out of the Fram?

My guess right now is that the ESS and Laptev will melt pretty far into the CAB due to all the warmth and sun they're getting, but the Beaufort and CAB north of the CAA will hold on because they're getting mostly cloud weather.


A-Team

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Re: The 2018 melting season
« Reply #1272 on: June 13, 2018, 08:11:48 PM »
The animation below looks at whether an UH AMSR2 overlay can somewhat differentiate genuine UB SMOS ice thinness from melted surface. (Passing weather can be somewhat distinguished by its rapid transit). Here AMSR2 and SMOS agree on open water (ice edge). The places where AMSR2 consistently shows less than 100% concentration (80% cutoff used below) are also places where SMOS mean grid cell thinness tends to be low.

Those AMSR2 regions, if not attributable just to dispersion, are also prime candidates for melt ponds.Thus even if the dotted outline in the final frame shows valid SMOS regions, melt + thinness would result in over-stating of actual ice thinness.

Jaxa seems to track melt surfaces in some sense but its color complexity and separate weather artifacts are difficult to coordinate with SMOS.

In summary, SMOS isn't easy to correct this time of year nor it it entirely a throw-away.

aperson

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Re: The 2018 melting season
« Reply #1273 on: June 13, 2018, 10:04:55 PM »
Does anyone know of anywhere that maintains current and historical time series for the Dipole Anomaly? It seems the Arctic Oscillation is the only mode of the Arctic SLP EOF that gets any notoriety, but the DA is what matters in melt season.

My initial hypothesis after watching this event is that a strong -DA followed by a +DA or vice-versa is the most effective way to create rapid melt, especially when albedo is higher. Increased variance in the DA should then correlate with increased melt.

seaice.de

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Re: The 2018 melting season
« Reply #1274 on: June 13, 2018, 10:33:38 PM »
In summary, SMOS isn't easy to correct this time of year nor it it entirely a throw-away.

Better use SMOS brightness temperatures this time of year because the "thickness" is misleading and non linear.

http://icdc.cen.uni-hamburg.de/1/daten/cryosphere/l3b-smos-tb.html

Pagophilus

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Re: The 2018 melting season
« Reply #1275 on: June 13, 2018, 10:44:18 PM »
Blue sea ice starting to show strongly in the southern CAA

First image unaltered, second has color saturation pushed to +50 in Photoshop

Pagophilus

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Re: The 2018 melting season
« Reply #1276 on: June 13, 2018, 11:34:57 PM »
More on my lonely obsession with that tongue of dispersing sea ice south of Franz Josef Land.  The semi-parallel patterns visible in the photos I now believe are 'stringers' of slushy, melting sea ice that have detached from this tongue and are floating to oblivion in the Barents. 

It is possible to observe this phenomenon elsewhere in the current melting Arctic, but not on this scale, and since this area has been largely covered with clouds over the past two or three weeks, the sheer magnitude of what is happening has been hidden from view.  Basically, there appears to be a vast field of these 'slushy stringers', maybe around 100,000 km2, spreading into the Barents and fading away there. 

Top image gives general context.  Second image is from the top center of this one, and you can see how the ice front gradually degenerates into these 'stringers'.  Third image is from the center of the photo and near the center of the field showing how these can look like banks of coherent clouds... but I am confident they are not.  To those expecting big extent drops,much of this 'stringer field' probably counts as more than 15% ice concentration on AMSR2, but cannot last much longer.

Apologies to all old hands who have seen this all before and whose elbows have just slipped off the table as they fell unconscious reading this.   All images unaltered Worldview.   

Hyperion

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Re: The 2018 melting season
« Reply #1277 on: June 14, 2018, 12:44:09 AM »
5 day current and SST update has happened on null school. Peak Gulfstream speed has gone up another 0.4 kmph. With more of it going north rather than turning back into the Atlantic. This 50% increase in the flow speed, combined with the broad wind driven surface flow being shoved north by the strong Greenland vortex/central Atlantic ridge dipole winds, and the reduced flow escaping back down the European coast probably means more than twice the normal flow rate into the Arctic basin is occurring with the thermal energy available to melt ice possibly double that again. This flow appears to be increasing at an increasing rate. But even if all the weather systems conspired to work against it, they would have to hold that formation for months to overcome the momentum built up. At present it looks like they are doing everything they can to accelerate both its inflow, and the surface flush to make room for it. And plan to continue doing it. There's even a eastward bend in the Bering inflow current, and low pressure systems over the Beaufort are helping with inflow draw and surface freshwater expulsion, definitely not good for the future of the ice.
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NACK

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Re: The 2018 melting season
« Reply #1278 on: June 14, 2018, 01:41:55 AM »
The exact details of the metrics are not important unless you are in a boat trying to avoid sea ice. What's important is how the ocean/ice/atmosphere/biosphere system is changing as GHGs add planetary heat. We are arguing over fine details about sea ice extent that are insignificant to the big picture. The amazing Greenland vortex we have seen this late spring is a very anomalous feature which our discussion is ignoring while we argue over details about extent and area that will be wiped out in a few weeks time.

The 90 pattern of winds and currents has been very efficiently transporting cold water into the Labrador sea, followed by deep convection as it mixes with warm Gulf stream water. This weather/current pattern is speeding up the rate of transport of Gulf Stream water across the temperate north Atlantic then up the coast of Norway. There has been a stunning anomalous amount of northwards heat transport in the north Atlantic over the past 90 days that will affect the Arctic for many months.

A lot of attention on Russian side of arctic but I am for one am watching the CAB for a route to sail through (and cheering for the melt).

Looks like BBQ weather has has finally arrived on the northern coast. Yes!

Hyperion

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Re: The 2018 melting season
« Reply #1279 on: June 14, 2018, 02:50:52 AM »
Well NACK, when you look at the upper level steerage from the high altitude winds at 250 hPa, and mean sea level pressure, we have a strong cross polar jetstream setting up that will steer incoming low pressure systems from the NW Pacific and Asia over Alaska and into the Beaufort and CAA. When you look at the total precipitable water and low level 1000 hPa winds, there is an absurd amount of moisture and energy inbound already, being thrown north by systems already on the runway. You probably wouldn't be jumping the gun if you upped anchor within the next few weeks. Or even days.

Quote from: NACK link=topic=2278.msg158683#msg158683 date=1528933315
[quote author=FishOutofWater link=topic=2278.msg158616#msg158616 date=1528909770
The exact details of the metrics are not important unless you are in a boat trying to avoid sea ice. What's important is how the ocean/ice/atmosphere/biosphere system is changing as GHGs add planetary heat. We are arguing over fine details about sea ice extent that are insignificant to the big picture. The amazing Greenland vortex we have seen this late spring is a very anomalous feature which our discussion is ignoring while we argue over details about extent and area that will be wiped out in a few weeks time.

The 90 pattern of winds and currents has been very efficiently transporting cold water into the Labrador sea, followed by deep convection as it mixes with warm Gulf stream water. This weather/current pattern is speeding up the rate of transport of Gulf Stream water across the temperate north Atlantic then up the coast of Norway. There has been a stunning anomalous amount of northwards heat transport in the north Atlantic over the past 90 days that will affect the Arctic for many months.

A lot of attention on Russian side of arctic but I am for one am watching the CAB for a route to sail through (and cheering for the melt).

Looks like BBQ weather has has finally arrived on the northern coast. Yes!
[/quote]
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.
https://en.wikipedia.org/wiki/McGillicuddy_Serious_Party

Greenbelt

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Re: The 2018 melting season
« Reply #1280 on: June 14, 2018, 03:42:31 AM »
If GFS is to be believed, two back to back strong storms heading poleward in the Atlantic over the next week. Both begin to start filling in before reaching the ice edge. That's the first storm winding down over the ice in the 2nd image.


Pagophilus

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Re: The 2018 melting season
« Reply #1281 on: June 14, 2018, 04:22:53 AM »
This weather/current pattern is speeding up the rate of transport of Gulf Stream water across the temperate north Atlantic then up the coast of Norway. There has been a stunning anomalous amount of northwards heat transport in the north Atlantic over the past 90 days that will affect the Arctic for many months.

And on that note, this image from nullschool showing SST anomalies highlights how the Arctic is besieged by two unusually warm, vast oceans.  The track of heat, often noted by Fish, Hyperion and others, from the huge warm mass in the North Atlantic all the way through to the Barents Sea is striking.  So is the unusually warm condition of the Bering Sea, but of course the narrowness of the Bering Strait limits its influence.
« Last Edit: June 14, 2018, 05:22:56 AM by Pagophilus »

Frivolousz21

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Re: The 2018 melting season
« Reply #1282 on: June 14, 2018, 04:37:39 AM »
The smos thickness is totally bunk.  It's not debateble. 
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Pagophilus

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Re: The 2018 melting season
« Reply #1283 on: June 14, 2018, 04:49:37 AM »
SMOS may be misleading for the amateur like myself right now, but see the quote from seaice.de below.  It is evidently useful in winter.  And it can provide information to the sophisticated user in summer -- but on melt-ponding and not on ice thickness.



SMOS sea ice thickness is only reliable when its cold. The penetration depth decreases when the ice is getting warm. Therefore UH stops delivering Arctic sea ice thickness products in April and starts only in October.

Look at figure 6 in https://www.the-cryosphere.net/8/997/2014/tc-8-997-2014.pdf
« Last Edit: June 14, 2018, 04:56:22 AM by Pagophilus »

Avalonian

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Re: The 2018 melting season
« Reply #1284 on: June 14, 2018, 04:52:54 AM »
Where SMOS was showing open water appearing in the CAA a couple of days ago (southern channels), it's now visible on Worldview... and is clearly just extensive (and rapidly-appeared) melt-ponding. For now. So, yeah, at the moment it's clearly trying to trick us.

Thomas Barlow

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Re: The 2018 melting season
« Reply #1285 on: June 14, 2018, 05:23:22 AM »
Quote
No chance of an ice-free Arctic for at least 20 years.

That is false. There is a very low chance this year, increasing  every year that gets warmer and the weather more extreme. Saying there is no chance it will happen before 2037 is simply not true.
This year the uncertainties are the early opening of the Bering, a thin CAB, no ice North of Svalbard and the ever present warmer planet.
What if I said 15 years instead? Would that satisfy you?
There really is no chance of an ice-free Arctic for at least 15 years, but probably more like 20 years. The ice extent will continue to extend in winter, and will continue to bulge up and thicken against the CAA and Greenland. That the whole thing could be less than 15% in a few years is unlikely.
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.

aperson

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Re: The 2018 melting season
« Reply #1286 on: June 14, 2018, 05:28:19 AM »
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.

Ice-Free in this forum is typically understood to mean < 1 million km^2 of sea ice extent to avoid this sort of semantic debate.

Pagophilus

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Re: The 2018 melting season
« Reply #1287 on: June 14, 2018, 05:49:59 AM »
I think a large part of the issue here is that most scientists acknowledge that they cannot be sure how complex systems will respond to stresses in the future, and therefore they speak and write in terms of probability.  Thus Archimid states there is a chance, but only a very low chance that the Arctic would melt out this year, and that the probability increases in future years as the Earth (probably) warms up.  It really is the only sensible way to speak of the future.  If we toss ten pennies, it is unlikely that all ten will come up heads, but it is also possible, and we can assign a (low) numerical probability to that.

It is difficult to predict possible outcomes in the case of huge natural systems like the Arctic, but we can ascribe probabilities based upon trends, algorithms, computer models etc.  Then the experts argue about it all, gather more evidence and recalibrate their predictions, which is how it should be in science.  And we continue to be surprised, and often humbled, by how the planet and the Arctic responds.

Quote
No chance of an ice-free Arctic for at least 20 years.

That is false. There is a very low chance this year, increasing  every year that gets warmer and the weather more extreme. Saying there is no chance it will happen before 2037 is simply not true.
This year the uncertainties are the early opening of the Bering, a thin CAB, no ice North of Svalbard and the ever present warmer planet.
What if I said 15 years instead? Would that satisfy you?
There really is no chance of an ice-free Arctic for at least 15 years, but probably more like 20 years. The ice extent will continue to extend in winter, and will continue to bulge up and thicken against the CAA and Greenland. That the whole thing could be less than 15% in a few years is unlikely.
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.
« Last Edit: June 14, 2018, 06:08:05 AM by Pagophilus »

bbr2314

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Re: The 2018 melting season
« Reply #1288 on: June 14, 2018, 06:05:04 AM »
Albedo projections from Copernicus would validate the idea that the pack is splitting into two. The uptick in extent is probably part of this happening. It will be catastrophic for volume in the short term and extent/area imminently.

By 8/1 I find it exceedingly unlikely that the two primary red remaining areas of thick ice are still a coherent mass.

I would also think that despite area #s being technically above 2016, the total amount of high-latitude ocean exposed in 2018 seems much greater (as Hudson and Kara are holding up numbers as well). This would likely lend itself to continued momentum longer in the season for critical high-latitude CAB ice given the open ocean's propensity for accumulating heat.

Neven

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Re: The 2018 melting season
« Reply #1289 on: June 14, 2018, 07:00:18 AM »
What if I said 15 years instead? Would that satisfy you?
There really is no chance of an ice-free Arctic for at least 15 years, but probably more like 20 years. The ice extent will continue to extend in winter, and will continue to bulge up and thicken against the CAA and Greenland. That the whole thing could be less than 15% in a few years is unlikely.
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.

Let's stay on-topic, please.
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Frivolousz21

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Re: The 2018 melting season
« Reply #1290 on: June 14, 2018, 07:51:48 AM »
The models are now backing away from there prior colder huge NA side PV look.


Towards a quick shift through a weaker transient PV towards either a dipole anomaly or just a huge ridge over the central basin.

While the CAB has been protected.   Overall things have still fallen towards setting up for a potential major melt season if a dipole pops into the first half of July.


2015 proved July can essentially make up for June.


Although that was record setting.
I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Often Distant

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Re: The 2018 melting season
« Reply #1291 on: June 14, 2018, 09:21:05 AM »
Things warming up in the archipelago.

deconstruct

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Re: The 2018 melting season
« Reply #1292 on: June 14, 2018, 11:00:36 AM »
this morning when i was looking at : https://ads.nipr.ac.jp/vishop/#/extent
[..]
and now the models want to make us believe that zero ice has been melting yesterday ?
I don't know what is your problem. You are not looking at a model, but on measurements dervied from sensor data.
So there are some things like
  • clouds, that block the sensor from seeing the ice surface correctly
  • melt ponds, that are not distinguishable from open water for the sensor
  • uncertaintity in measurement (no measurement is 100% accurate)
  • ice movement, e.g. dispersion and compaction, which will change extent, but not necessarily that there was melting or not
  • waves or rain (that lead to ice floes being flooded by water and therefore not detected as ice)
  • extent thresholds where pixels might change from non-ice to ice because it just barely moved above the threshold

So, no, the "model" doesn't want you to believe that there was no melt.
But you should at least understand what that chart shows and what not, before drawing conclusions.

And just a hint:
Ice area measurements have uncertainties as has every measurement.
Ice extent day to day variation can be caused by things that have nothing to do with melt.
There will always be day to day variation, due to those uncertaintites and the other things I described. Hence it just doesn't make sense to look at those variation and mistake them for trend.

Over a longer period, like a week or more, most of these issues go away to the most part. So I would recommend looking at it with that in mind.

With 1407 posts, I thought that you would know those things anyway, or I just didn't get that your post was just a joke.

Neven

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Re: The 2018 melting season
« Reply #1293 on: June 14, 2018, 01:03:18 PM »
Okay, back on topic.  :)
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F.Tnioli

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Re: The 2018 melting season
« Reply #1294 on: June 14, 2018, 02:05:58 PM »
... Fresh snow has a very high albedo (reflects 95% of solar radiation) so might delay ice melt once the sun rises.  Thick snow may 'hide' melt ponds delaying their absorbing most of the solar radiation.  These would be positive feedbacks (positive here being 'good for the ice').   But snow may have negative feedbacks as well:  clouds (especially low clouds) in the winter will reduce heat loss to space (Paul showed how recent winters have been rather warmer than it used to be). ...
A request: while what i quoted is true per se, can we all stick with the standard terminology for feedbacks, which is "positive" for any feedback which amplifies the base process, and "negative" for any feedback which slows down the base process. This logic will persist, i am sure, since it's scientifically sound and always applicable, while "positive as in "good"" is subjective; so, using them the way Tor used them in the quote above - will breed more confusion for some, i think...

Dharma Rupa

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Re: The 2018 melting season
« Reply #1295 on: June 14, 2018, 02:10:42 PM »
A request:... "positive" for any feedback which amplifies the base process, and "negative" for any feedback which slows down the base process....

Yes please.

F.Tnioli

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Re: The 2018 melting season
« Reply #1296 on: June 14, 2018, 02:23:38 PM »
As far as i see it, the models are not telling that no ice melted. The models are telling that plenty of ice melted. Only that area on the siberian side lost maybe 500 km3 in the last 10 days. If the graphs are right.
Thanks, Alexander. I'll just add to this that amount of energy required to turn 500 km3 of 0°C ice into ~500 km3 of 0°C liquid water - is ~ (334 kJ/kg x 500.000.000.000.000kg) = 1,67 x 10^20J. This amount of energy - huge; same amount of energy is released by exploding 2.650.793 "Little Boy" atomic bombs (one such bomb incinerated Hiroshima at the end of World War 2, releasing 6,3 x 10^13J of energy). So, like blowing up over 2,5 MILLION nukes in 10 days. So yep, this is big.

F.Tnioli

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Re: The 2018 melting season
« Reply #1297 on: June 14, 2018, 03:38:23 PM »
My understanding of 15% for extent is that it was picked for navigation vs being indicative of the ice  in general, its continued use is because extent data is our oldest dataset so it affords us better historical comparison.
My understanding matches dosibl's (where 15% came from and why we continue to use it).  SIE numbers were never intended to make anybody believe we had that much 'completely iced over' expanses.
That, and the numbers are much more consistent than any other metric.
This consistency can be quite misleading. Physically, "amount" of ice is not its extent - but its volume. Which means, for example, that when you want to know how long sea ice would last, in any specific situation / area, be it during particular season or on any longer timescales, - extent is not the thing to look at, if you want to be sure. Volume is. It's possible to "approximate" using extent - but _only_ when certain circumstances do not change. Which nowadays, they do.

Pagophilus

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Re: The 2018 melting season
« Reply #1298 on: June 14, 2018, 04:15:38 PM »
A request:... "positive" for any feedback which amplifies the base process, and "negative" for any feedback which slows down the base process....

Yes please.
Double yes please.  It becomes a very tangled discussion otherwise.

coyoteyogi

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Re: The 2018 melting season
« Reply #1299 on: June 14, 2018, 06:12:20 PM »
I have a basic question for Hyperion and others. How and when will we know IF the gulf stream has connected with the warm water coming into the Chukchi from the Pacific? Are there buoys taking this measurement? Ships? it seems like it would be beyond the capacity of satellites if it happens under the ice.
It does strike me that this would be a game changing event for the durability of the ice cap.