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slow wing

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Re: The 2018 melting season
« Reply #2900 on: August 18, 2018, 07:37:45 AM »
Quote

The U. Bremen site that I had been using previously has been down for several days. Do we know why and have the reasons been posted here?
Always assume nefarious intent from the usual suspects. Of course I don't have proof they had to move it for disorderly behavior. Politics is not science so I suggest take these insinuating questions elsewhere.
I don't understand that response at all. It was a straight question and it related only to the science, not to politics. I don't know the reasons and asked for them only as a way to help determine how long the site and data is likely to be down for.

At the discretion of anyone who knows, they are of course welcome to instead answer that directly: how long are the site and data likely to be down for? That is what is directly relevant to me and to this thread as I had been posting images sourced from there every day on this thread.
« Last Edit: August 18, 2018, 07:51:31 AM by slow wing »

Sterks

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Re: The 2018 melting season
« Reply #2901 on: August 18, 2018, 08:12:37 AM »
It’s called dark sense of humor, don’t take it personally
Thx for the NSIDC animation, very revealing of the effect of weather on ESS.

Pmt111500

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Re: The 2018 melting season
« Reply #2902 on: August 18, 2018, 08:21:07 AM »
Ah, on that I've got no idea. There's just been a series of DNS attacks on EU servers, maybe that's got them. Sorry for the inconvenience.

Sterks

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Re: The 2018 melting season
« Reply #2903 on: August 18, 2018, 08:44:52 AM »
And more interesting weather to affect ESS and Arctic Ocean in general. This is EC forecast, day 4 from now.
It's not the Arctic Dipole, but it's another dipole on the Arctic.  Will bring heat, winds and conpaction from Laptev to ESS to Beaufort, and ruin the chances of the pack getting "unhinged" like a reality star from Canada and Greenland.

Rob Dekker

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Re: The 2018 melting season
« Reply #2904 on: August 18, 2018, 10:41:37 AM »
The U. Bremen site that I had been using previously has been down for several days. Do we know why and have the reasons been posted here?

I don't think that anyone has posted an explanation yet.
But there were issues with the AMSR2 satellite data over the past couple of days, as noted here :
https://forum.arctic-sea-ice.net/index.php/topic,2223.msg167447.html#msg167447

Even JAXA was blind for a couple of days due to satellite issues.
Now that JAXA is back up, I would hope that Uni Bremen will resume shortly.
This is our planet. This is our time.
Let's not waste either.

oren

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Re: The 2018 melting season
« Reply #2905 on: August 18, 2018, 10:53:51 AM »
NSIDC ice concentration maps show a week's action in the Arctic basin, ending on the map most recently released, 2018-08-16 - see first figure.

The U. Bremen site that I had been using previously has been down for several days. Do we know why and have the reasons been posted here?
Slow Wing, first I'd like to thank you for your daily sea ice concentration animations. Very useful in tracking what's really happening, beyond the headline extent numbers.
I'm not sure why the site is down, but I would recommend using the UH site for now. I have a link to their ftp site, far from the convenience of the UB image browser, but the site is up and the resolution is actually much higher than UB's thanks to different processing of the data.
ftp://ftp-projects.cen.uni-hamburg.de/seaice/AMSR2/3.125km/
Maybe user seaice.de has a better link?

binntho

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Re: The 2018 melting season
« Reply #2906 on: August 18, 2018, 11:11:57 AM »
Greenland liftoff set to continue for the next couple of days, nullschool shows winds from the south and southwest, with a strong Foehn effect (adiabatic warming) off the Greenland Ice Cap. Image for 00:00 UTC on the 19th.
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binntho

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Re: The 2018 melting season
« Reply #2907 on: August 18, 2018, 11:20:23 AM »
However the massive low pressure area building up to the east of Svalbard seems set to push the ice back against Greenland, and perhaps even out through Fram Strait? Nullschool from 09:00 UTC on the 21st.

It's interesting to see temperatures above zero at the very tip of the Wulff Land peninsula, with air that seems to have been blown straight across the entirety of the CAB.

because a thing is eloquently expressed it should not be taken to be as necessarily true
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gerontocrat

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Re: The 2018 melting season
« Reply #2908 on: August 18, 2018, 11:51:10 AM »
Ah, on that I've got no idea. There's just been a series of DNS attacks on EU servers, maybe that's got them. Sorry for the inconvenience.
The University of Bremen website is not dead.
The sea ice bit is dead. Are they on holiday?
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binntho

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Re: The 2018 melting season
« Reply #2909 on: August 18, 2018, 11:54:54 AM »
I've identified four floes north of the Ryder Glacier fjord (don't know if it has a proper name), the animation shows the 13th and the 17th, both with fairly clear skies, and I've attempted to indicate both movement and rotation of the floes.

Movement is less than 20 km between the images, but it's clear that they all rotate, the yellow one by more than 90 degrees counter-clockwise, and except for the double-red piece floating out from land, the all rotate in the same direction.

Whether this is due to wind or currents I've no idea!

because a thing is eloquently expressed it should not be taken to be as necessarily true
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NeilT

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Re: The 2018 melting season
« Reply #2910 on: August 18, 2018, 12:07:53 PM »
The Are they on holiday?

That was my suspicion.  Usually if the European servers have issues in August it takes time to get them fixed as the month of August is holiday time...
Being right too soon is socially unacceptable.

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gerontocrat

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Re: The 2018 melting season
« Reply #2911 on: August 18, 2018, 01:32:37 PM »
Attached are GFS 5-day average temp and average temp anomaly for the Arctic. 3 day, 5 day,10 day the images look the same (even as far back as early August).

Relative warmth from the Atlantic side to way across the pole, relative cold on the Pacific side.
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Phil.

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Re: The 2018 melting season
« Reply #2912 on: August 18, 2018, 09:37:06 PM »
Thanks Phil -


Maybe you would like to start a thread for their expedition progress and see how they get on in Dogbark! - I found:
http://arcticnorthwestpassage.blogspot.com/2018/08/northwest-passage-on-dogbark.html

Here's a shot of them anchored up in the shelter of Cross Island a few days ago, surrounded by all that 7/10th ice.   ;)

https://i1.wp.com/saildogbark.com/wp-content/uploads/2018/08/ABF640A7-F559-4FD7-8B42-78DBC084D7CC.jpeg?resize=600%2C429&ssl=1

A-Team

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Re: The 2018 melting season
« Reply #2913 on: August 18, 2018, 11:09:59 PM »
Here are some crazy ice floe trajectories for Lincoln Sea and Cape Morris Jesup for Aug 2018 from DMI's archive of Sentinel-1B images. Binnho posted some nice ones too at #2909, from WorldView.

Winds have been weak this summer at the CMJ AWS so ice movement offshore probably reflects advection and turbulent eddies in surface water. Overall, there is net transport westward at ~60 km north of the entrance to the Nares. However along the coast of MJand also Ellesmere, there's been return flow.

The big event coincided with some remarkable weather, a high of 13.4ºC (56ºF) on August 3rd and strong winds of 42 km/h to the west, very close to the date of the remarkable ice lift-off and surge westward. Open water reached its northernmost extent on Aug 13th at 84.5º, some 105 km north of the nearest land but still 610 km short of the pole.

Given excellent 2m hourly observational data from CMJ, Alert, Nord etc weather stations, it makes no sense to use GFS at nullschool other than for an atmosphere overview. GFS does not incorporate Greenland data as tie points and often gets wind and weather at the level of ice pack completely wrong. Nullschool did ok on the wind on Aug 3rd but missed the peaks and never saw the temperature surge. https://tinyurl.com/y8wyltb5

Observed ice pack motion, deduced from rolling satellite pairs, correlates very poorly with modeled pressure highs and lows and resulting wind forecasts.

This is why, with 4 ships out there now, it is important to get real data on conditions as we hardly ever know what is really going on. And especially ice thickness from Oden: not passenger anecdotes during the sail but actual drilled ice thickness and ice temperature profile when then the ship is tethered to its floe.

And speaking of total lack of tie points, how does Oden measured ice thickness compare to Piomas etc at the same lat,lon and date? Are we ok with 25% error in ice volume models?

Oden is doing some very interesting work on bubble content of the ice, aerosols, clouds and radiative fluxes but will we need to wait 2-3 years on journal articles as just happened with N-ICE2015?
« Last Edit: August 19, 2018, 04:05:42 AM by A-Team »

DavidR

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Re: The 2018 melting season
« Reply #2914 on: August 19, 2018, 03:14:16 AM »
However the massive low pressure area building up to the east of Svalbard seems set to push the ice back against Greenland, and perhaps even out through Fram Strait? Nullschool from 09:00 UTC on the 21st.

Todays Worldview shows this building into the most cyclonic weather pattern I've seen in the Arctic, Perhaps its just that the central eye is so visible with open water below. It will be interesting to see its effect over the next few days. If it is as strong as it looks, and keeps moving toward the Pole, the Atlantic / Russian side of the pack will be heavily impacted.
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Stephan

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Re: The 2018 melting season
« Reply #2915 on: August 19, 2018, 08:39:32 AM »
The Are they on holiday?

That was my suspicion.  Usually if the European servers have issues in August it takes time to get them fixed as the month of August is holiday time...
This is the official announcement from Uni Bremen:
"Aufgrund einer technischen Störung können zur Zeit leider keine aktuellen Karten angezeigt werden!" which means "we are sorry that due to a technical problem no actual maps can be provided". The latest date shown is Aug 14, 2018. See also https://www.meereisportal.de/
« Last Edit: August 19, 2018, 09:23:52 AM by Stephan »
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gerontocrat

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Re: The 2018 melting season
« Reply #2916 on: August 19, 2018, 09:22:11 AM »
Summer is over North of 80 says the average temperature graph.

Not quite - says the estimate of actual temperature North of 80.
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oren

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Re: The 2018 melting season
« Reply #2917 on: August 19, 2018, 09:57:24 AM »
Here is an animation of the last few days using the UH AMSR2 concentrations. I intentionally left it at the highest resolution, though made an effort to crop it. Click and zoom.
I think the arctic still has lots of relatively easy ice, rather southerly and low concentration, that could still melt out and take extent down quite a bit. It is mainly found in the ESS (huge potential), the CAA, the Beaufort, the Chukchi-facing CAB, and Foxe Basin. Alternatively, a long round of properly-oriented wind could cause an immense compaction event.
It's all up to the weather as usual, but don't bury this season just yet.

silverslith

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Re: The 2018 melting season
« Reply #2918 on: August 19, 2018, 10:40:54 AM »
Tethered profiler. Itp108 is screaming out the southernmost channel of the CAA. Velocity has increased from 0.9m/s to 1.2m/s or 4.3km/hr in the last 2 days. The crawler is either damaged or does not have enough power to crawl up and down the cable with the difference in surface and current speed at depth, but is recording over 34psu at 230m depth. This is saltier than Pacific waters, so it must be that Atlantic tropical waters have reached the inner Beaufort.

http://www.whoi.edu/itp/itp108data.html

Thawing Thunder

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Re: The 2018 melting season
« Reply #2919 on: August 19, 2018, 12:06:51 PM »
Looks like bigger drops are in the making.
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A-Team

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Re: The 2018 melting season
« Reply #2920 on: August 19, 2018, 01:10:10 PM »
The animation below highlights residual sea ice of intermediate concentration for the first 18 days of August. Here land, open water, and solid ice (80-100%) are masked, leaving the ice in between to display (inverted from the original UH AMSR2).

As noted last year, this coming month is a window of vulnerability for intermediate ice, with wind and waves the principal issues rather than diminishing air temperatures and insolation. Strong winds with long persistent fetches suffice to churn the ice and mix surface waters, there is no requirement for these winds to originate in another great arctic cyclone.

The central dark region in the final frame suggests the lower bound at the minimum. It's possible though that the Banks Island portion will become isolated from the main CAB and indeed be entirely exported out through the Amundsen Gulf.

Day to day change is fairly slow but the second animation shows quite a bit has happened in the first 18 days of this month.

If the lift-off continues offshore along the CAA creating a whole ice pack detachment (WIPD), it will become possible for the first time to entirely circumnavigate the ice pack staying within the Arctic Basin. This was nearly attained on August 18th as the dotted line route shows below. (Here it is assumed that sufficient open water can be found within ice of <20% to allow passage.)
« Last Edit: August 19, 2018, 01:47:43 PM by A-Team »

Dharma Rupa

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Re: The 2018 melting season
« Reply #2921 on: August 19, 2018, 01:49:32 PM »
Summer is over North of 80 says the average temperature graph.

Not quite - says the estimate of actual temperature North of 80.

Now we wait for the first hint of what the freezing season is going to be like.

A-Team

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Re: The 2018 melting season
« Reply #2922 on: August 19, 2018, 04:41:47 PM »
Please, not again. The freeze forum will be started by Neven approximately a month from now.

Air temperatures take a back seat for the next six weeks to far more potent water temperatures and winds. There is nothing to be learned at this time of year from petty variations in that 80ºN chart.

Somewhere in the Arctic Ocean, 24/7/365, ice is freezing (for example, leads in mid-summer). Somewhere in the Arctic Ocean, 24/7/365, ice is melting (for example, Bering Strait or north of Svalbard).
« Last Edit: August 19, 2018, 05:00:06 PM by A-Team »

Jim Hunt

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Re: The 2018 melting season
« Reply #2923 on: August 19, 2018, 05:33:15 PM »
I think the arctic still has lots of relatively easy ice, rather southerly and low concentration, that could still melt out and take extent down quite a bit. It is mainly found in the ESS (huge potential), the CAA, the Beaufort, the Chukchi-facing CAB, and Foxe Basin.

Cross posted from the NW Passage thread, my alter ego's musings on the prospects for small "yachts" attempting to navigate those "waters" this summer:

http://GreatWhiteCon.info/2018/08/the-northwest-passage-in-2018/


Quote
The central section between Bellot Strait and Gjoa Haven and/or Cambridge Bay is still chock a block.

Meanwhile the Canadian icebreaker CCGS Amundsen has sailed past Arctic Bay and Resolute.

I cannot help but wonder what vessels might be closely following in his wake?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Phil.

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Re: The 2018 melting season
« Reply #2924 on: August 19, 2018, 06:50:23 PM »
Observed ice pack motion, deduced from rolling satellite pairs, correlates very poorly with modeled pressure highs and lows and resulting wind forecasts.

This is why, with 4 ships out there now, it is important to get real data on conditions as we hardly ever know what is really going on. And especially ice thickness from Oden: not passenger anecdotes during the sail but actual drilled ice thickness and ice temperature profile when then the ship is tethered to its floe.


Some interesting developments reported by Helen Czerski from the Oden:
"Today is the first day I’ll go out on the ice to work.
Except that I won’t. The morning patrol found a crack which may partially cut off the open lead from the rest of the floe.  The sites closer to the ship are fine so the weather scientists can continue to build their masts, and the ice scientists can keep digging a hole to deploy their underwater robots. But those of us interested in open water have to wait until the crew have worked out the safest option to get us to the lead, and there’s so much other work going on that this will take a while."

jdallen

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Re: The 2018 melting season
« Reply #2925 on: August 19, 2018, 07:02:39 PM »
The animation below highlights residual sea ice of intermediate concentration for the first 18 days of August. Here land, open water, and solid ice (80-100%) are masked, leaving the ice in between to display (inverted from the original UH AMSR2).
<snippage>

The central dark region in the final frame suggests the lower bound at the minimum. It's possible though that the Banks Island portion will become isolated from the main CAB and indeed be entirely exported out through the Amundsen Gulf.

Day to day change is fairly slow but the second animation shows quite a bit has happened in the first 18 days of this month.
<snippage>

Great animation and commentary as usual.  The animation is useful as it shows clearly the ice tongue extending from Banks island into the Amundsen gulf isn't a persistent block, but rather it's steady export from the local pack into a very hot killing zone, something I had not noticed previously.

Further details I'm picking out - it looks like the southern route of the NW Passage may indeed be about to open up, or has the potential too before we run out of insolation this melt season.

As you say, everything rides on the weather, which even at this late stage could make as much as a 500,000KM2 difference (or more) in the final numbers.

Perhaps that is a testament to just how vulnerable the ice has become.
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Shared Humanity

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Re: The 2018 melting season
« Reply #2926 on: August 19, 2018, 07:18:13 PM »
The early southerly dislocation of the cryosphere is going to prove increasingly impactful if the recent models are to be believed.

We are now labeling weather "the cryosphere"?
If you don't know what "cryosphere" means try Googling before clogging up the melt thread w stupid questions (there's a thread for those as well).

https://oceanservice.noaa.gov/facts/cryosphere.html

https://forum.arctic-sea-ice.net/index.php/topic,143.0.html

^if you want to continue asking stupid questions I suggest you take the topic there, link provided for your courtesy (you have to click it to access).

And your link makes clear just how foolish your comment is. The Cryosphere is a portion or region of the planet that is characterized by frozen water. This includes permafrost, ice sheets, ice caps, glaciers, snow and frozen water. In this context, what on earth do you mean by...

The early southerly dislocation of the cryosphere is going to prove increasingly impactful if the recent models are to be believed.

gerontocrat

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Re: The 2018 melting season
« Reply #2927 on: August 19, 2018, 07:30:36 PM »
The animation below highlights residual sea ice of intermediate concentration for the first 18 days of August. Here land, open water, and solid ice (80-100%) are masked, leaving the ice in between to display (inverted from the original UH AMSR2).

Utterly and totally awesome, A-Team. I downloaded it and got it on full screen using the windows photos utility. Oh for a big screen instead of a bog-standard laptop.

I hope you will give us the longer duration one come September.
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A-Team

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Re: The 2018 melting season
« Reply #2928 on: August 19, 2018, 07:49:59 PM »
'Communications' from the Oden appear scattered over a dozen internet sites -- a huge task to keep up with, distill to something useable here, tie into melt season, or use for ground-truthing our favorite satellite resources. Still, it is more information than we get from self-absorbed millennial trust funders blogging their latest Arctic adventure-travel.

It looks like they have an onboard intranet that is not being shared with the outside world, possibly because of limited bandwidth (though HC and others are still twittering graphics and frankly it costs pennies a day to send compressed text over Iridium whereas total costs per day at sea probably exceed $25,000.00).

However it is possible to mouse along the route and scrape off some non-ice data at https://oden.geo.su.se/map/

The ice does not look that great past the open lead, it appears flooded. Even standing there, I would not know how to score it for Piomas, area, extent and concentration maps. Still no word on ice thickness though in the past we've gotten at that from freeboard showing at edges.

The key point is without back-tracking this floe, we won't know where it has been, when it formed, or what temperature history it experienced. Consequently its thickness is largely uninterpretable. Is it representative of adjacent or even regional ice?

They had a clear day. Too bad they elected to park at a pole hole for most satellites. (N-ICE2015 made a huge effort to coordinate with simultaneous satellite and aircraft passes, to improve their calibration.) Sentinel-2AB has three channels at 10m resolution from which we can extract rather good 5m.

I've posted the lead graphic at its original resolution as there are clues in the detail.

https://polarforskningsportalen.se/en/arctic/expeditions/arctic-ocean-2018/blogs
https://twitter.com/helenczerski?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Eauthor
https://www.helenczerski.net/
https://physicsworld.com/a/behold-the-bubbly-ocean/ H Czerski 2017

Quote
...the biggest bubbles probably stay in the top metre or two, and that these are the most important vehicles for CO2 transfer into the ocean. We’re starting to separate out the effects of turbulence stirring the water and the bubbles themselves, when it comes to how gases are transferred across the surface. We know that bubbles probably don’t matter very much at all for some gases (like dimethylsulphide) and matter a lot for others (CO2).

The aerosols produced by bubbles affect cloud formation, and as ocean biology changes, the aerosols may too. As the extent of summer sea ice in the Arctic Ocean continues to reduce, that newly open ocean will start to see more breaking waves and bubbles, and more aerosol production.

But how will that affect the weather near the pole, and what consequences will it have for those of us living at lower latitudes?

See also: @IanMBrooks, @MattESalter, @Arctic_Andy, @DrPrytherch, @CKatlein @gshowalt, @AmandaGrannas and @ArcticKerri @SvenskPolarforskning  #ArcticOcean2018

Quote
CLOUDS CONTROL THE ENERGY BUDGET
The key to understanding this environment is energy: the balance between the energy coming in from the Sun, that lost from the surface, and its distribution in between. This is why the critical focus on this project is on the clouds – the presence, thickness and type of Arctic clouds in summer is still poorly understood, but it is the clouds that control the energy budget. They are generally mixed phase (a mixture of water droplets and ice crystals), with a complex structure. Cloud formation is linked to the ocean, because it seems that material ejected from the ocean may be an important source of cloud condensation nuclei and ice nucleating particles, tiny particles which are necessary for clouds to form. In turn, the clouds will affect the ocean, by mediating the energy flow to and from the ocean surface. The ultimate source of the chemicals that form those important particles is likely to be ocean life, and so the expedition must include biological studies, as well as physical and chemical observations.

To study this interlinked and complex system, scientists will make observations from three major areas: from the ship itself, from the large ice floe we will be moored against, and from other ice floes a few miles from the ship.

The movement of water and ice will be studied using remotely operated underwater vehicles, buoys, acoustical devices for measuring currents, and observations of ice movement. Other monitoring stations will also follow the changes to the ice as the season progresses. The physics driving the production of bubbles in the gaps between ice floes will also be studied, along with the bubbles themselves and the particles they produce as they burst at the ocean surface. Other teams will measure and sample the microbiology in the water, taking samples back to the ship to test their response to changing physical and chemical water conditions. The sea surface microlayer, with its distinctive chemical and biological features, will be sampled directly so that its composition can be analysed. The effects of increasing CO2 levels on the ice and nearby biology will also be tested in shipboard experiments. Methane and CO2 fluxes from the open leads will also be measured.

In the atmosphere, extensive sampling of aerosols particles and gases will be carried out, using samples collected at the ship and from balloons. The structure of the atmosphere and the local clouds will be measured from balloons and using remote sensing technologies – LiDAR and radar. General weather measurements will be carried out continuously.
« Last Edit: August 19, 2018, 08:37:18 PM by A-Team »

Dharma Rupa

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Re: The 2018 melting season
« Reply #2929 on: August 19, 2018, 07:52:58 PM »
Please, not again. The freeze forum will be started by Neven approximately a month from now.
Don't worry -- though a transition thread might be interesting.

Air temperatures take a back seat for the next six weeks to far more potent water temperatures and winds. There is nothing to be learned at this time of year from petty variations in that 80ºN chart.
I have to disagree with you here because what DMI 80N does now tells me how much water vapor is really in the air.

Niall Dollard

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Re: The 2018 melting season
« Reply #2930 on: August 19, 2018, 08:56:50 PM »

The big event coincided with some remarkable weather, a high of 13.4ºC (56ºF) on August 3rd and strong winds of 42 km/h to the west, very close to the date of the remarkable ice lift-off and surge westward. Open water reached its northernmost extent on Aug 13th at 84.5º, some 105 km north of the nearest land but still 610 km short of the pole.

Given excellent 2m hourly observational data from CMJ, Alert, Nord etc weather stations, it makes no sense to use GFS at nullschool other than for an atmosphere overview. GFS does not incorporate Greenland data as tie points and often gets wind and weather at the level of ice pack completely wrong. Nullschool did ok on the wind on Aug 3rd but missed the peaks and never saw the temperature surge.

I wonder what was the official maximum temperature at Cape Morris Jesup (pictured) on August 3rd ?

At 19UTC the temperature was as high as 13.4 C. There was some big fluctuations that day coupled with changes in wind direction. Biggest change of all occurred between the hours of 12 and 13 UTC with a rise in temp from 4.7 C to 17.0 C ! 

Either this figure is erroneous or possibly the change in wind direction to SSW indicates a downslope fohn type wind coming down form the mountainous interior creating a rapid rise in temperature ?   

gerontocrat

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Re: The 2018 melting season
« Reply #2931 on: August 19, 2018, 11:20:50 PM »
Air temperatures take a back seat for the next six weeks to far more potent water temperatures and winds. There is nothing to be learned at this time of year from petty variations in that 80ºN chart.

What I have learnt from that chart is that air temperatures North of 80 over the last 10 days or so seem to have been the warmest since 2002.
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A-Team

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Re: The 2018 melting season
« Reply #2932 on: August 20, 2018, 12:01:24 AM »
Quote
a rise in temp from 4.7 C to 17.0 C !  possibly  a downslope fohn wind form the mountainous interior creating a rapid rise in temperature ?

Nice data! Did a temperature surge show up at the two flanking stations Nord and Alert with time delays appropriate to a system sweeping westward?

Morris Jesup is one of the few places in Greenland that does not have regular katabatic (downslope) winds according to DMI. However it was quite warm just to the west on August 3rd, 15.2ºC

http://www.dmi.dk/fileadmin/user_upload/Rapporter/TR/2000/tr00-18.pdf see fig. 5, page 19

https://earth.nullschool.net/#2018/08/02/2100Z/wind/isobaric/1000hPa/overlay=temp/stereographic=-45.00,80.87,2971/loc=-48.159,82.004

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jdallen: the ice extending around Banks island into the Amundsen gulf isn't a persistent block, but rather it's steady export from the local pack into a very hot killing zone, not noticed
Right. There was quite a shift in mid-summer from Beaufort ice curling up the coast in eddies to being exported out the Amundsen and M'Clure, continuing to progress for the next several days. It is almost as though a large western section of CAB/CAA is being torn off above Prince Patrick. This would be a big deal as the central ice pack has largely stayed intact until the north Greenland event and now this. The images below look at this at the higher resolution UH AMSR2.

This has resulted in a faux melt anomaly in the Beaufort sector this summer due, as Oren notes, to the failure of the 'seas' approach to take visco-elastic ice advection from one sea to another into account. That is, the ice may be melting "as expected" but it is soon replaced with other ice giving the impression it is not melting even as the donor sea is not notably depleted.
« Last Edit: August 20, 2018, 03:58:59 PM by A-Team »

Jim Hunt

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Re: The 2018 melting season
« Reply #2933 on: August 20, 2018, 01:16:24 AM »
What with one thing and another I still haven't finished my article on the topic of circumnavigating Greenland.

Nonetheless I figured y'all might be interested in the current location of the good ship Polarstern on cruise PS115?
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Tony Mcleod

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Re: The 2018 melting season
« Reply #2934 on: August 20, 2018, 02:13:32 AM »
Extraordinary images A-Team.

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Re: The 2018 melting season
« Reply #2935 on: August 20, 2018, 02:54:27 PM »
Bremen is Up...
Self-sufficiency and Durability to disasters are the absolute keys to nearly any disaster you can think of such as War, economic collapse, pandemics, Global warming, quakes, volcanoes, Hurricanes... all of which put solar farms etc. and power grids at risk!

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Re: The 2018 melting season
« Reply #2936 on: August 20, 2018, 04:23:07 PM »
That's not much ice left. I'm curious if the ice near the canada/alaska coast will melt out and what will be left of the Chukchi/ESS in 2 weeks time.

Luckily the melt season is slowing down and nearing it's end/ enter the probably long transation to freezing season

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Re: The 2018 melting season
« Reply #2937 on: August 20, 2018, 05:41:13 PM »
That's not much ice left. I'm curious if the ice near the canada/alaska coast will melt out and what will be left of the Chukchi/ESS in 2 weeks time.

Luckily the melt season is slowing down and nearing it's end/ enter the probably long transation to freezing season
I expect significant losses will occur in the ESS, a slug of the remnant in the Beaufort will disappear, as well as some bite out of the cab.  I expect the southern arm of NW Passage will open up as well.

All in all, I think we will finish somewhere in the 2nd through 5th category.
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Aluminium

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Re: The 2018 melting season
« Reply #2938 on: August 20, 2018, 06:42:09 PM »
August 11-19.

A-Team

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Re: The 2018 melting season
« Reply #2939 on: August 20, 2018, 08:55:59 PM »
Quote
I expect significant losses will occur in the ESS, a slug of the remnant in the Beaufort will disappear, as well as some bite out of the CAB.  the southern arm of NW Passage will open up as well. we will finish somewhere in the 2nd through 5th category.
Sounds about right except for PrPa/Banks and Lincoln Sea but how would mid-September look if the August calendar were given a few extra days along the lines of:

Aug 01
Aug 02
Aug 03a
Aug 03b
Aug 03c
Aug 03d
Aug 03e
Aug 03f
Aug 03g
Aug 04
Aug 05
Aug 06
Aug 08
Aug 09
Aug 10
...

Speaking of bathwater, the southern Chukchi and north Svalbard get all the attention but it is the Laptev that has really reached alarming water temperature anomalies.

Left as exercise: how much energy would it take to lower the temperature of the top meter of Arctic Ocean not currently covered by ice to the freezing point and beyond, include in your answer the ratio of energy to lower to energy to energy of phase change, using today's area/extent, and the time and volume of dry still air at -20ºC and 1 atm needed to achieve this cooling.

https://www.nature.com/articles/s41467-018-05256-8

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Scientists are generally confident in the thermodynamic drivers of these changes but are less so in dynamic aspects4,5. Another pronounced signal of anthropogenic global warming is the rapidly increasing near-surface temperatures in the Arctic at a pace two to four times faster than the rest of the globe, known as Arctic amplification....

Due to declining sea-ice, the Arctic Ocean absorbs more incoming solar radiation from spring to autumn. By early winter, when near-surface air temperatures drop below sea-surface temperatures, this excessive heat is released into the atmosphere6,10,11,12,13. The additional heat inflates the lower troposphere over the Arctic Ocean and nearby continents, and increase geopotential heights, which could affect circulation patterns further south.
« Last Edit: August 20, 2018, 09:30:17 PM by A-Team »

Stephan

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Re: The 2018 melting season
« Reply #2940 on: August 20, 2018, 09:45:39 PM »
Thank you A-Team for the reference and for the beautiful graphs. I also wonder how much elevated SST would affect the forthcoming freezing season. Will there be a delay in ice formation in comparison to previous years in Laptev, N Barents, S Chukchi or Bering Sea?
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RoxTheGeologist

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Re: The 2018 melting season
« Reply #2941 on: August 20, 2018, 11:06:43 PM »
Thank you A-Team for the reference and for the beautiful graphs. I also wonder how much elevated SST would affect the forthcoming freezing season. Will there be a delay in ice formation in comparison to previous years in Laptev, N Barents, S Chukchi or Bering Sea?

My guess would be the depth of convection caused by cooling will increase. If the deeper water has been warmed through insolation, then the whole shallow shelf water column may end up convecting as it cools. Convection happens normally, forming the Arctic Mixed Layer when brine is released during ice formation, but warming the deeper water makes overturning more energetically favorable as it is less dense than normal. I guess I'm predicting that the SST isn't critical, but the heat stored at depth is.

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Re: The 2018 melting season
« Reply #2942 on: August 20, 2018, 11:13:31 PM »
SSTs look quite tame to me.  Compare current to 2007

In 2007 the warm ocean seemed to retard freeze for a few weeks with -ve anomalies on area dropping quite a lot (nearly 1m sq km from memory) in the few weeks after minimum.  After that freeze went rapidly and made up most of the lost ground within a few more weeks.
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Re: The 2018 melting season
« Reply #2943 on: August 20, 2018, 11:14:05 PM »
Quote
wonder how much elevated SST would affect the forthcoming freezing season
Good question. While we wait for jd to crunch the numbers, it is worth asking whether we should be monitoring -- and comparing year-on-year -- the heat burden in near-surface waters that accrues during melting season. The temperature of open surface water is observable by satellite and the depth of the mixing layer is known though we don't have the temperature profile without operational buoys.

The overall heat budget of the Arctic Ocean is greatly influenced by incoming Atlantic Waters; though these are initially at ~300m depth, they don't exit with all the heat they brought in. Over the short term, this lost heat doesn't much influence temperatures of surface waters.

Other complications come in from sunlight penetrating thinner ice quite effectively, warming the water below. And that sunlight can fuel algal growth on the underside of the ice which then adsorb the energy right there rather than it going deeper in the water column.

In any event, Mercator Ocean only offers 2017 and 2018 for today's date (plus various water depths, not shown). The animation below compares them by arithmetic variations (such as subtraction of pixel RGB values) directly on the graphics. That leads to new colors though and so 2D color legends.

Water temperatures now should have considerable predictive power as to which peripheral ice sectors will melt out over the next month (if only we knew how the floes would move relative to warmer water temperatures). At the end of melt season, these surface temperature pockets suggest lagging areas of freeze-up (if only we knew what air temperatures would be associated with them).

Last winter, elevated Bering Sea temperatures (and lack of ice) were unprecedented. The Chukchi didn't fully freeze until early January. How much of that should be attributed to local SST vs imported SST vs mixing layers vs currents/eddies vs air temperatures?

Quote
Compare current to 2007
How? It's in a distorted cylinder projection, doesn't go above 80ºN and is unreadable/unreliable there, plus it would have to be cut down to comparable ice covers which isn't practical without having the data in polar stereographic projection. Are the grid cells really of adequate resolution for the Arctic seas and islands -- I can barely make out Greenland.

 Overall, there are a great many climate statistics like this, really focused on the equator and mid-latitudes, with the poles just bones thrown to the dog. We are not so interested in oblique observation of the Arctic from satellites in equatorial orbits, as is done for example with lightning. Data quality deteriorates with latitude -- even the 80º cutoff is likely a stretch.
« Last Edit: August 20, 2018, 11:48:47 PM by A-Team »

Dharma Rupa

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Re: The 2018 melting season
« Reply #2944 on: August 20, 2018, 11:14:53 PM »
I guess I'm predicting that the SST isn't critical, but the heat stored at depth is.

Hard to say at the moment, but certainly in the long run.

I think the question will come down to sea surface salinity, but I am guessing.  I still think it possible to sop up enough of the freshwater lens during freezing to cause overturning any time of year.

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Re: The 2018 melting season
« Reply #2945 on: August 21, 2018, 12:18:49 AM »
NSIDC's Chartic just lurched sideways right into 2015.  2018 is now on the same path as 2017, just with a lot more ice extent.

2 weeks of August left and 1-2 weeks of September left.

It is a most interesting season.  One more step on the road to destruction wearing the face of something else.

We shall see if the ESS and Laptev finally succumb, but, even if they do not, the damage done elsewhere is long lasting.
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Michael Hauber

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Re: The 2018 melting season
« Reply #2946 on: August 21, 2018, 01:40:22 AM »

How? It's in a distorted cylinder projection, doesn't go above 80ºN and is unreadable/unreliable there, plus it would have to be cut down to comparable ice covers which isn't practical without having the data in polar stereographic projection. Are the grid cells really of adequate resolution for the Arctic seas and islands -- I can barely make out Greenland.

[/quote]

How?  By opening your eyes and having a look.  It might not be as pretty or as easy to read as the newer charts, but the comparison is still very obvious that 2007 had a lot more warm ocean surface than this year.  Stands to reason as 2007 started with substantial amounts of thick multi-year ice, this year followed on from the warmest winter ever, and the multi-year ice basically gone.  But conditions in 2007 melted more ice than the conditions this year.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

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Re: The 2018 melting season
« Reply #2947 on: August 21, 2018, 03:29:28 AM »
Summer is over North of 80 says the average temperature graph.
Not quite - says the estimate of actual temperature North of 80.
With the sun now less than 13arcdeg above the horizon(& decreasing a third of an arcdeg, & accelerating, per day) at the North Pole, & ever enlarging chunks of the Arctic in quickly increasing darkness, direct solar TSI in the Arctic is rapidly ending for the year. It has been the solar TSI, which has been the greatest forcing in the Arctic for 2+ months, as it almost always does in the summer. The TSI, which has been substandard for 12+(more?) years, is having a lowering effect on Arctic summertime temperatures.
Now tho, with the TSI Arctic strength weakening quickly, ever increasing man-made, infra-red energy absorbing GHG volumes are taking the place of sub-standard TSI, already floating Arctic temperatures above norms & will continue on the average to widen the gap from "normal Arctic temperatures" into & thru much of the winter.   

oren

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Re: The 2018 melting season
« Reply #2948 on: August 21, 2018, 03:50:51 AM »
The TSI, which has been substandard for 12+(more?) years.
I  think you put too much repeated emphasis on the TSI, especially as I don't think this 12-years claim is even true.
I suggest to back it up with some data and historical charts, in an appropriate thread (not here).

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Re: The 2018 melting season
« Reply #2949 on: August 21, 2018, 05:57:30 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-20...