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Jim Pettit

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Re: The 2017 melting season
« Reply #1850 on: June 08, 2017, 01:26:39 PM »
There are at least ten or so recent comments in this thread mentioning (either directly or via quote) "data manipulation".

This isn't the place for that.

Per Neven's rules:

1) Every comment in the melting/freezing season threads should pertain to that subject. These are the most popular threads for readers who don't comment, so don't bother them with off-topic stuff.
2) If you have to be off-topic, be short.
3) If you're the third guy who wants to say something about the off-topic subject, say: Okay, guys, this is getting off-topic, let's go to this or that thread - or open a new one - so our discussions don't get lost and we don't bother others.


As the melting season ramps up, we'll have to start snipping OT stuff. Please help us keep this place clean and informative, not cluttered with CT arguments. Thanks...


magnamentis

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Re: The 2017 melting season
« Reply #1851 on: June 08, 2017, 02:03:41 PM »
Neven, 6.6.2017 snow diagram is erroneous in these areas which in reality have no snow cover:

1) around Finland
2) around the Bering Strait (Russian and Alaskan coasts of the Arctic Ocean)
3) around the Taimyr Peninsula (east side)


thank you so much for this, i had no clue how to say it but i was sure it is as you say but found no way to make my point. BTW there are other graphs that don't fit reality, i.e. above 80N temps anomaly by DMI, just dunno how to bring the information forward to make it bullet-proof, not
in the mood to start big discussions LOL
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Neven

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Re: The 2017 melting season
« Reply #1852 on: June 08, 2017, 02:07:25 PM »
I believe the IMS snow cover maps are created using multiple sensors and a human analyst interpreting them. Maybe they've incorporated new sources and this shows more snow than is actually there. It could be that just as with MASIE the data isn't ideal for interannual comparisons.

Hmmm, one to ponder.
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VeliAlbertKallio

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Re: The 2017 melting season
« Reply #1853 on: June 08, 2017, 03:27:32 PM »
No you are wrong! In close inspection you can see that the date was merely a day old at the time, 5th June 2017, not as 3rd June 2017 as you claim for whatever reason. (I am enclosing an enlargement to proof the above that I or Neven were not wrong with the date I gave.)

So I think, people recently observing meltwater pools on sea ice have been right, after all! I also think that errors like these contribute for the poor model output due to GIGO principle (performing poorly the further in time one goes as error builds up). Surely, say if Britain were put under snow cover, we would get wrong weather forecasts and more depressions 'forming' around the British Isles due to higher temperature gradients in the forecasting systems.

We used to have here in Bracknell (at the UK Meteorological Office) people with clips and scissors back in 1980's when some Russian ships sent out spurious data from the sparsely traveled parts of the Arctic Ocean and it was these recollections of mine that cropped in my mind to audit NOAA's snow data graph with satellite photos. On those days (1980's) satellites were far fewer and in winter it was really hard to get any data from places like the Barents Sea, the Kara Sea, with one odd ship traveling there giving fantastically wrong readings could give a wrong impression over very vast areas of the Arctic Ocean. Thus, I recall a weather forecast in 1981 when the Finnish MTV made a news weather forecast for a midwinter weekend ahead promising a thaw of +3C, which then turned out to be -25C breeze. This became a huge scandal with people calling for the news forecaster to be turned off the air. Here in Bracknell, we used to censor many Russian ships on those days for not being serious in passing weather and temperature data correctly. An error could just come if a kitchen or sauna window was left open and leaking heat to the thermometer. This passed to the weather forecasting system would blow out as an Arctic heatwave of +3C in January when it was -25C.

People are giving US$ 400million per annum for climate change denialist camp and any increased unreliability on weather forecasts will also throw doubt over the reliability of climate modeling. People like money and the Republicans have at least since COP15 (Copenhagen) talked bull sh*t which they must know isn't true, may be they have got a few chaps from NOAA joining them...   

What is going on and why is disinformation being published?


Different dates: The Snow and Ice Charts were from June 3, 2016 & 2017.  Veli posted images from June 6.  A lot can happen in snow cover over just a few days at this time of year.  Here's the latest:



Neven

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Re: The 2017 melting season
« Reply #1854 on: June 08, 2017, 03:40:27 PM »
Albert, please, stay on-topic and/or keep it short, or I'm going to start snipping.
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gerontocrat

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Re: The 2017 melting season
« Reply #1855 on: June 08, 2017, 04:39:23 PM »
Some more boring (mostly JAXA and believed to be reliable) numbers.

If the melt from now (June 8th) to minimum continues at the average of the last 10 years, minimum would be 4.25 million km2.

To become the 2nd lowest minimum, i.e. just over 4 million km2, remaining melt would have to be about 3.2% greater than that 10 year average.

To become lowest, i.e. just under 3.2 million km2, remaining melt would have to be about 16% greater than that 10 year average.

If from now to minimum remaining melt repeated the 2012 outlier, minimum would be about 2.95 million km2. But this would require remaining melt to be circa 20 % greater than the previous 10 years average.

These figures have barely changed over the last 3 weeks. There are about 100 melting days at most  remaining, of which at least 10 one would expect to be low.

In the next few days I see no major weather changes (from cci-reanalyzer) to kick melting into high gear. Today’s Arctic temperature anomaly is just + 0.11  degrees Celsius. The 5 day forecast anomaly is a very pale pink for the CAB.  DMI 80+N is just below average. Maximum insolation is only 2 weeks away. Weather-forecast.com  forecasts do show a lot of clear skies especially  on the Pacific half of the CAB but no major weather systems.

In contrast the average thickness graph is truly scary, the images all say the ice-cap is a load of rubble.

Only a relatively small increase over the average melt  (which is the trend throughout the satellite record) would make 2017 second lowest.  Given a coolish and quiet arctic summer this would be very significant, perhaps more so than a record low due to extreme weather anomalies.

I expect this post to be immediately followed by appearance of the June cliff. As a numbers man, I can only wait for the numbers.
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seaicesailor

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Re: The 2017 melting season
« Reply #1856 on: June 08, 2017, 05:24:01 PM »
@gerontocrat in all honesty I think the next four days (or more) bring surface melt conditions to many areas of the Arctic proper.
The temp. anomalies lose relevance just about now until september.
Better look at temperatures directly

« Last Edit: June 08, 2017, 05:37:44 PM by seaicesailor »

Lord M Vader

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Re: The 2017 melting season
« Reply #1857 on: June 08, 2017, 05:52:59 PM »
SIS and gerontocrat: yes, temp anomalies are becoming more or less pointless at this time of year. More useful to look how large part of Arctic that has temps above zero including the weather conditions.

A high pressure dome is currently located over Beaufort and Chukchi sea. Temps were above 0 over a large part of ESS, Laptev and the CAB this morning while being below 0 over most of Beaufort and Chukchi. Just west of Pevek in Siberia one can see that the temps are about +10oC and melt ponds are visible in this region. See: http://ocean.dmi.dk/arctic/weather/arcticweather_imagecontainer.php

The high pressure system is forecasted to linger over Beaufort, ESS and Chukchi for about 6-7 more days bringing clear skies, rising temps and melt ponds onto the ice. Beyond D7 a possible scenario is a weakening by the high pressure followed by another high pressure building in over the same area as the previous one.

And don't forget that the Atlantic sector seems to have both more and thicker ice compared to for ex 2016 and 2012. All in all, we should expect ourselves to see a lot of century breaks to come soon!!

Thomas Barlow

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Re: The 2017 melting season
« Reply #1858 on: June 08, 2017, 06:46:15 PM »
Does anyone have volume graph for Arctic Ocean only (Beaufort, Chukchi, East Siberian, Laptev Seas, Central Arctic)?  Jim Hunt posted a good one for area last month that I think he made from the data?  Volume anyone?
https://forum.arctic-sea-ice.net/index.php/topic,1834.msg113969.html#msg113969

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Re: The 2017 melting season
« Reply #1859 on: June 08, 2017, 07:48:15 PM »
The N-ICE2015 papers have arrived, 22 of them. These papers represent six months of precious at-sea observations coordinated with simultaneous overhead remote sensing. While somewhat dated at 30 months, they remain very relevant to this spring’s melt season along the Arctic Ocean periphery north of Svalbard.

The papers are listed here along with their key points and download status: http://onlinelibrary.wiley.com/10.1002/(ISSN)2169-9291/specialsection/NICE1/

Some of these are currently paywalled, others are open source or available from https://sci-hub.cc/ (or TOR scihub22266oqcxt.onion) using the doi. Clicking then on ⇣ сохранить статью downloads the article or final draft as a pdf. It’s not currently known if US copyright law applies to Russia under self-anointed US exceptionalism — or vice versa under a stronger principle of Russian exceptionalism. Unblocked supplemental is available separately at journal sites.

The question is, do we muddle along without anyone reading these papers? Frankly, that’s not sustainable; we’re not here to promulgate anachronistic misinformation. There’s a definite need for fresh air in our near real-time interpretation of satellite ice products for the Svalbard-FJL periphery. Six months data from the ice changes everything.

I tried below with one of these papers to see if it is feasible to concisely summarize full texts, lessons learned without the length. No, it is not.

Mixing rates and vertical heat fluxes north of Svalbard from Arctic winter to spring
aMeyer, I Fer, A Sundfjord, A Peterson
3 June 2017 DOI: 10.1002/2016JC012441
http://onlinelibrary.wiley.com/doi/10.1002/2016JC012441/full

The observations cover the deep Nansen Basin, the Svalbard continental slope, and the shallow Yermak Plateau from January to June 2015. Average winter heat fluxes during quiet times in the ice-covered Nansen Basin are 2 watts per sq meter at the ice-ocean interface, 3 within the orderly density gradient (pycnocline) below the surface mixed layer and 1 below.

These heat fluxes are dwarfed In late spring over the Yermak Plateau by heat fluxes of 300 close to the surface. The forcing factors here are wind, near-surface warm Atlantic Water, steep shelf topography and above all, storms:

Wind forcing increases turbulent dissipation seven times in the upper 50 m, and doubles heat fluxes at the ice-ocean interface. The presence of warm Atlantic Water close to the surface increases the temperature gradient in the water column, leading to enhanced heat flux rates within the pycnocline. Steep topography consistently enhances dissipation rates by a factor of four and episodically increases heat flux at depth. It is, however, the combination of storms and shallow Atlantic Water that leads to the highest heat flux rates observed: ice-ocean interface heat fluxes average 100 W m−2 during peak events and are associated with rapid basal sea ice melt, reaching 25 cm per day.

That would be 2 meter thick ice gone in 8 days if the storms lasted that long at peak intensity (which they don’t).

In the Arctic, sea ice at the surface reduces the transfer of wind energy to the ocean, causing turbulent dissipation rates to be an order of magnitude smaller than at lower latitudes. Away from boundaries, mixing of the Arctic water column is dominated by much smaller lateral intrusions and double diffusive fluxes of temperature and salinity gradients.

Without the sea ice cover, energy from winds, ocean tides, currents and breaking internal waves interact with topographic features on the sea floor to bring turbulent vertical mixing of previously stable stratifications. That’s especially pronounced over the rough topography of the Yermak Plateau northwest of Svalbard which has twice-daily strong barotropic tides. At its coriolis latitude, extracted energy cannot propagate away as linear internal waves and so dissipates locally, with rates of sufficient magnitude to greatly enhance impacts of Atlantic Water on regional ice cover. This water is normally isolated from sea ice by intervening cold Polar Surface Water stratification.

The Atlantic Water inflow is the main source of oceanic heat to the Arctic Ocean but little of that heat actually has reached the sea ice in the past, though that is changing with newly thinner ice, a longer season of open water, and more frequent and extreme storms from the south.

The RV Lance completed four drifts in the Arctic north of Svalbard anchored to different floes, the most favorable drift track (Floe #3) running from April 18th to June 5th. Their profiler instruments measured turbulent heat flux in the upper 300 m of the water column. 

The depth of the upper boundary of Atlantic Water, different from the depth of the 0°C isotherm, was found as shallow as 30 m depth and as deep as 300 m.

The large heat flux values observed at the 0°C isotherm can be explained by the fact that the 0°C isotherm is a natural boundary between waters from the Arctic at the surface (Polar Surface Waters and warm Polar Surface Waters) and waters with Atlantic origin at intermediate depths (either Modified Atlantic Water or Atlantic Water). These two families of water masses have such distinct temperature characteristics that this boundary has large temperature gradients.

The heat flux peaks coincided with periods of large basal sea ice melt. A major melt event took place on 16 February [see 10.1002/2016JC012011,10.1002/2016JC012403, 10.1002/2016JC012195] during a large winter storm but no data were recorded due to foul weather and sea ice conditions.

The largest heat flux estimates during N-ICE2015 were recorded when the proximity to Atlantic Water was combined with storms. This happened three times: on 16 February, 2–5 June, and 11–13 June 2015. During each of these events, a storm took place, ice drift speeds were larger than 0.4 m s−1, and Atlantic Water was present at less than 100 m depth. Heat fluxes at the ice-ocean interface averaged 106 W m−2 during the last event in June. These enhanced heat fluxes lead to the warming of the water below the sea ice, which in turn triggered large basal sea ice melt. A basal melt of 25 cm/d was recorded from 5 June at the end of Floe 3, and again during Floe 4 after 10 June 2015.

Ice mass balance buoys also observed rapid sea ice melt during the 16 Feb 15 basal melt event and derived conductive heat fluxes estimates that peaked at 400 W m−2 These extremely large basal melt events led to the decay of the ice, making it more vulnerable to swell and waves, and ultimately to break up events.

The combination of storms and shallow Atlantic Water both in winter and summer induced large ocean heat flux of order 100 W m−2 in the upper ocean associated with massive basal sea ice melt events. This highlights the importance of predicted increased storm frequency in the Arctic that could erode local stratification and tap into warm subsurface Atlantic Water. In winter, this would lead to reduced growth, weakening, and even melting of the sea ice, while in spring such events would accelerate the melting and breakup of the sea ice. The warming and shoaling of the Atlantic Water inflow north of Svalbard and in the Barents Sea combined with increased storm frequency could lead to a significant reduction in sea ice cover further along the Atlantic Water inflow.

« Last Edit: June 08, 2017, 07:56:47 PM by A-Team »

RoxTheGeologist

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Re: The 2017 melting season
« Reply #1860 on: June 08, 2017, 08:58:34 PM »

Thanks A-Team, for heads up that these papers exist and the long synopsis. There has been a lot of speculation on the forum about how storms affect the pycnocline, and there is good solid data to clarify our suppositions.

The change in the heat flux is astounding, and shows the amount of trapped heat in the Atlantic Waters. The analysis of the ice edge correlating with the shelf that you made backs up the observation that the combination of storms and topography with a shallow 0°C isotherm causes dramatic basal melt. It's worrying though, that even with a deep >100m 0°C isotherm (deep Atlantic Waters), key storms increased heat flux by 3x and increased the dissipation within the pycnocline.

Lord M Vader

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Re: The 2017 melting season
« Reply #1861 on: June 08, 2017, 09:00:05 PM »
Interestingly, ECMWF 12z op run depicts a possible "Little MAC" in 9 days bottoming out at about 978 hpa in the vicinity of Laptev Sea. Such a scenario should have big impacts for the melting season. Any one here who has an idea about the lowest June SLP is in the Arctic basin? Neven?

By D10, the "Little Mac" has the opportunity to grow in size and move into the CAB.

This scenario is something that we need to watch in the upcoming runs!

EDIT: "Little MAC" is here referred to a "Little Moderate Arctic Cyclone" :)

Neven

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Re: The 2017 melting season
« Reply #1862 on: June 08, 2017, 11:30:11 PM »
Interestingly, ECMWF 12z op run depicts a possible "Little MAC" in 9 days bottoming out at about 978 hpa in the vicinity of Laptev Sea. Such a scenario should have big impacts for the melting season. Any one here who has an idea about the lowest June SLP is in the Arctic basin? Neven?

I don't have the numbers in my head, but last year saw a couple of cyclones and 2013 too, I believe. I saw that cyclone in the forecast yesterday as well (or was it this morning). 978 hPa is pretty low and should stir up things on the Siberian side. If it comes about, of course. Like you say, the forecast is for D9, which is highly unreliable.

In the meantime, I wonder what the effect of all the high pressure will be. I'm somewhat surprised that there is so little blue to be seen on the Worldview images, although I don't have the exact dates for previous years either.
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Rob Dekker

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Re: The 2017 melting season
« Reply #1863 on: June 09, 2017, 05:29:29 AM »
I believe the IMS snow cover maps are created using multiple sensors and a human analyst interpreting them. Maybe they've incorporated new sources and this shows more snow than is actually there. It could be that just as with MASIE the data isn't ideal for interannual comparisons.

Hmmm, one to ponder.

Good point, Neven.
It may be that the land snow numbers are tainted by human influence, but they are the best we have right now.
What I'm more bothered about is that we still have no publicly available database that has (gridded or scalar) land snow cover on a daily basis (with history). NOAA and Rutgers publish monthly numbers only, and the only way to obtain daily numbers appears to be to pixel-count their images from a stereographic projection image.

Tigertown

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Re: The 2017 melting season
« Reply #1864 on: June 09, 2017, 06:56:47 AM »
Subtle withdrawal.
June 4-9
CLICK IMAGE PLEASE

peterlvmeng

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Re: The 2017 melting season
« Reply #1865 on: June 09, 2017, 07:51:23 AM »
Interestingly, ECMWF 12z op run depicts a possible "Little MAC" in 9 days bottoming out at about 978 hpa in the vicinity of Laptev Sea. Such a scenario should have big impacts for the melting season. Any one here who has an idea about the lowest June SLP is in the Arctic basin? Neven?

I don't have the numbers in my head, but last year saw a couple of cyclones and 2013 too, I believe. I saw that cyclone in the forecast yesterday as well (or was it this morning). 978 hPa is pretty low and should stir up things on the Siberian side. If it comes about, of course. Like you say, the forecast is for D9, which is highly unreliable.

In the meantime, I wonder what the effect of all the high pressure will be. I'm somewhat surprised that there is so little blue to be seen on the Worldview images, although I don't have the exact dates for previous years either.

Subtle withdrawal.
June 4-9
CLICK IMAGE PLEASE


The melting ponds are not obvious at the beginning of June.But HP dome in the future will create many melting ponds in the Central Arctic. The ice is becoming blue and dark in June 9 of Worldview images. I am quite interested to see how the melting ponds affect the melting process in the following days.

S.Pansa

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Re: The 2017 melting season
« Reply #1866 on: June 09, 2017, 08:08:51 AM »
What effects will all the high pressure have? TOPA4 predicts quite some thinning across the Arctic, especially in the Chukchi, ESS and Laptev.
While that ist not really surprising in June the difference to 2016 is - to my eyes - striking. The area where the ice is barely a meter thick is huuuge.

If I assume - just as a loose thought-experiment - that all the ice below 1.5 meters will melt away, well ....


S.Pansa

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Re: The 2017 melting season
« Reply #1867 on: June 09, 2017, 08:17:42 AM »
Just to get a feeling how much ice usually melts from here to Mid-September. That's how the ice looked on 10th September 2016

Tigertown

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Re: The 2017 melting season
« Reply #1868 on: June 09, 2017, 08:46:06 AM »
Warm air at 850 mb coming into the Arctic and some of it makes it's way to the surface. The invasion continues in the following days, though the pattern moves around.

Jim Hunt

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Re: The 2017 melting season
« Reply #1869 on: June 09, 2017, 11:36:12 AM »
Does anyone have volume graph for Arctic Ocean only (Beaufort, Chukchi, East Siberian, Laptev Seas, Central Arctic)?


See:

http://GreatWhiteCon.info/2017/06/facts-about-the-arctic-in-june-2017/#comment-221986

I'm not aware of such a thing currently, but if you want to pick up the baton?!
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seaicesailor

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Re: The 2017 melting season
« Reply #1870 on: June 09, 2017, 06:38:30 PM »
The 2m temps today

[/quote]

Csnavywx

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Re: The 2017 melting season
« Reply #1871 on: June 09, 2017, 06:55:43 PM »
EOSDIS definitely showing signs of large scale melting/ponding. A few more days of this should render much of the cap a bluish color.

Lord M Vader

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Re: The 2017 melting season
« Reply #1872 on: June 09, 2017, 06:56:09 PM »
SIS & Co: with that temp map DMI temps above 80N should exceed or be very close to the freeze point. 12Z analysis temps uses to be somewhat colder.

johnm33

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Re: The 2017 melting season
« Reply #1873 on: June 09, 2017, 07:21:02 PM »
Looks like Greenlands coast in Lincoln is about to clear again,  https://go.nasa.gov/2t2VSSM

seaicesailor

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Re: The 2017 melting season
« Reply #1874 on: June 09, 2017, 07:56:42 PM »
5-day averaged MSLP forecast, and on the ensemble of the ECMWF
I mean, this is June 9, if this is not bad enough...

jai mitchell

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Re: The 2017 melting season
« Reply #1875 on: June 09, 2017, 08:04:23 PM »
an excellent summary discussion of the current melt season and how it is shaping up by Bob Henson on Weather Underground

https://www.wunderground.com/cat6/arctic-sea-ice-primed-phenomenal-melt-season
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Thomas Barlow

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Re: The 2017 melting season
« Reply #1876 on: June 09, 2017, 08:23:42 PM »
Does anyone have volume graph for Arctic Ocean only (Beaufort, Chukchi, East Siberian, Laptev Seas, Central Arctic)?

See:
http://GreatWhiteCon.info/2017/06/facts-about-the-arctic-in-june-2017/#comment-221986
I'm not aware of such a thing currently, but if you want to pick up the baton?!

Thanks, I'll give it a go.

Lord M Vader

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Re: The 2017 melting season
« Reply #1877 on: June 09, 2017, 09:15:15 PM »
Well, yes the sea ice could plummet to a new record low but how big would the damage be? IMO, it depends on how early the ice is breaking up. If it's breaking up in May it's extremely bad as it allows tremendeous amounts of heat to be stored by the open water as well to warm the water. OTOH, if the ice doesn't break up until the middle of August or later the damage is not as severe.

So while we might see a new record low later in the season that is bad but not nearly as bad compared to last year. Remember that the Beaufort Sea broke up very early. And so did Chukchi. Combined with a very warm winter there the ice over Chukchi never got a real chance to thicken properly. In 2012 it took more time for Chukchi to open up.

To conclude the whole thing: the fact that Chukchi Sea has opened up at a record pace is extremely bad and allows for a huge amount of heat to be trapped in that area. SSTs in the southern part of Chukchi is already about 1-2oC. If you get another month with sunshine over the open water....

If the upcoming freezing season is going to be even more pale than the last one, then the sea ice there will be in an even worse shape in 2018.

In ESS, I don't think it is as bad as in Chukchi. And that is because of the that it is considerably shallower than Chukchi. While it can warm up quick it also cools down quick when the fall is coming.

A-Team

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Re: The 2017 melting season
« Reply #1878 on: June 09, 2017, 10:30:25 PM »
Does anyone have volume graph for Arctic Ocean only (Beaufort, Chukchi, East Siberian, Laptev Seas, Central Arctic)?
Indeed it makes better sense to cut the cryosphere back to the Arctic Ocean (defined below so as to drop extraneous regions that melt out every year, padding the statistics with noise) and also to show not only the thickness maps (that provide the Piomas' volume number) but also the changing occupancy of thickness distribution bins in percent (shown for May 2017-2007, 2000, and 1979 below; basin-specific ice volume is not shown but is readily calculated from summing bin count x bin thickness).

The Piomas maps from @zlabe are cleanly colored and synched to their legend, allowing simple pixel counting of each thickness class (here 0.25 m increments). The polar stereographic projection is conformal so not equal area and so pixels need a latitudinal cosine correction, not applied below as it would just be swamped out by the small scale and other error considerations. There's been no open water in May so the various years all sum to the same total basin area.

I haven't come across accurate WGS84 number for either that area or total water volume as numerous definitions of 'Arctic Ocean' are in circulation. The other figure of interest is continental shelf area, say of 50 m or shallower. That is surprisingly large, about a third, according to the updated 2014 GEBCO bathymetry. Wind waves are capable of mixing to approximately that depth which has consequences for warming submerged permafrost currently capping methane and hydrates that have accumulated since the last interglacial.

The second image averages all 39 years. While the palette is not quite set up for that, the overall outcome affirms conventional wisdom of thicker ice along the CAA and falling off away from that. However the distribution is a bit more nuanced. Whether that distribution pattern is drifting towards something else might be tracked by over-weighting recent years.

The third image (cropped from Zack's twitter page with permission) shows all 39 years for May. The mask in the final frame shows the relationship of cryosphere to Arctic Ocean basin as operationally defined above.

The attached .txt file has the data (in csv format) used to make the thickness bin distribution inset; not all the years (or months) have been scored yet. To scale the method here -- say to score daily <gice>for 365 days x 39 years -- it would be better to go back to the original numeric data, though ImageJ can recover those right off a stack of graphics.
« Last Edit: June 09, 2017, 11:16:34 PM by A-Team »

Jim Hunt

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Re: The 2017 melting season
« Reply #1879 on: June 09, 2017, 11:06:46 PM »
The polar stereographic projection is conformal so not equal area and so pixels need a latitudinal cosine correction


PIOMAS actually uses:

A stretched generalized orthogonal curvilinear coordinate grid with the northern grid pole displaced into Greenland


http://psc.apl.washington.edu/zhang/IDAO/model.html

This causes the model to have its highest resolution in the Greenland Sea, Baffin Bay, and the eastern Canadian Archipelago.




 
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magnamentis

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Re: The 2017 melting season
« Reply #1880 on: June 09, 2017, 11:20:01 PM »
Interestingly, ECMWF 12z op run depicts a possible "Little MAC" in 9 days bottoming out at about 978 hpa in the vicinity of Laptev Sea. Such a scenario should have big impacts for the melting season. Any one here who has an idea about the lowest June SLP is in the Arctic basin? Neven?

I don't have the numbers in my head, but last year saw a couple of cyclones and 2013 too, I believe. I saw that cyclone in the forecast yesterday as well (or was it this morning). 978 hPa is pretty low and should stir up things on the Siberian side. If it comes about, of course. Like you say, the forecast is for D9, which is highly unreliable.

In the meantime, I wonder what the effect of all the high pressure will be. I'm somewhat surprised that there is so little blue to be seen on the Worldview images, although I don't have the exact dates for previous years either.

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The melting ponds are not obvious at the beginning of June.But HP dome in the future will create many melting ponds in the Central Arctic. The ice is becoming blue and dark in June 9 of Worldview images. I am quite interested to see how the melting ponds affect the melting process in the following days.

another one of those things we have to be wide open for changes and to change the way we look at things is melt-ponding.

in the past when the ice was over wide areas a more or less homogeneous mass, melt-ponding has certainly be the norm and a good indicator as well as that it had a significant impact..

i suspect, not totally sure though, that due to more fragmentation, more fissures and leads, that more and more of the melting surface will directly drain to the ocean and as a result there will be less melt-ponding but this would be no means mean less melting.

on the contrary, black surfaces (open ocean/leads) have a lower albedo than light blue melt ponds, the only thing i dunno is whether the ponds would warm up in a way and speed to accelerate over all melting more than the higher amount of movement (mechanical impact through wave action and mobility) together with the greater area of open water between the smaller and more numerous floes.
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A-Team

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Re: The 2017 melting season
« Reply #1881 on: June 10, 2017, 12:02:45 AM »
piomas grid been posted many times here.
That's where they run their algorithm (to avoid a pole hole singularity at sea by putting it in N Greenland), the output can be reprojected into any coord system. Note none of their input data comes in this coord system, it all has to be converted. Reply #1878 uses PS (or at least it superimposes well on known PS maps). It is 45º CCW from standard Greenland-down; that rotation would complicate the color palette. All displays on a computer screen ultimately use rectangular arrays of square pixels, never curvilinear.

Here are two graphics (from J Petit and L Hamilton) pulled from the most excellent wunderground post of Bob Henson mentioned above. What i consider the zone of vulnerability to total collapse of the ice -- volume below 2.25 -- has narrowed somewhat to six weeks. As many people have noted, we have no idea what weather will be during the low volume window this fall (if a really drastic low even emerges).

https://www.wunderground.com/cat6/arctic-sea-ice-primed-phenomenal-melt-season
« Last Edit: June 10, 2017, 01:54:58 AM by A-Team »

wallen

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Re: The 2017 melting season
« Reply #1882 on: June 10, 2017, 01:42:59 AM »
A close look at the EOSDIS Worldview, the sea ice appears to have completely come adrift from Greenland. Has this been known to happen before during the melt season and if so how soon into the season ?

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Re: The 2017 melting season
« Reply #1883 on: June 10, 2017, 02:50:33 AM »
Hi everyone. Here is a really rough plot I just did of our track on the R/V Lance...

I have added a few more pictures at https://twitter.com/ZLabe/status/873308423785390080.

Sea ice thickness in this portion of the Fram Strait averaged around 1.1-1.5 m with some floes containing negative freeboard. Snow depth was quite deep and reached nearly 0.5 m in some areas.
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Re: The 2017 melting season
« Reply #1884 on: June 10, 2017, 07:55:30 AM »
This  photo from Polarstern which went into Fram strait at the end of May shows just that. My interpretation is that ice which is thinning by bottom melt is pushed below the surface by its snow load. The snow is melted away by seawater from the floe edge inward. That the snow does not disappear quickly as soon as the ice sinks must be due to low air temperatures.
Does this make sense? 
https://blogs.helmholtz.de/polarstern/2017/06/angekommen-an-der-eiskante/

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Re: The 2017 melting season
« Reply #1885 on: June 10, 2017, 08:12:34 AM »
@ Andreas T

That ice looks really thin, thinner than it is supposed to be.
                                                                                                                                 
Below is the Beaufort Sea catching some rays
Blue is the one you see, as it goes deeper through the water before it breaks up. If it is reaching the water, so are the other bands.

« Last Edit: June 10, 2017, 08:24:50 AM by Tigertown »

subgeometer

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Re: The 2017 melting season
« Reply #1886 on: June 10, 2017, 08:59:30 AM »
Melt appeared immediately in the open water from FJL through the Barents Sea so bottom melt must be going on nearby as well, there's been a fair bit of wind in the region. The image is from June 9  -edit: this area is still showing as solid white on the NSIDC extent chart despite the totally open strip being over 50km wide!

There's also strong wind forecast in the Chukchi for the next day or 2 which will keep the ice retreating
« Last Edit: June 10, 2017, 09:07:24 AM by subgeometer »

Andreas T

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Re: The 2017 melting season
« Reply #1887 on: June 10, 2017, 10:27:36 AM »
@ Andreas T

That ice looks really thin, thinner than it is supposed to be.
                                                                                                                                 
Below is the Beaufort Sea catching some rays
Blue is the one you see, as it goes deeper through the water before it breaks up. If it is reaching the water, so are the other bands.
How thick is it supposed to be? We don't know how thick this particular area is by any other measurement, all larger areas contain ice of varying thickness and published measurements are averages. The reason I said bottom melt is that the ice must have been thicker when the snow fell on it. The caption says it is near the edge of the ice pack, we know in the Fram strait there is warm water moving in from the south and melting ice rapidly. No one can claim to know how thick this particular floe was 8 days ago.
The other part of your post doesn't make sense to me, what bands are you talking about? Are you talking of ice being blue? Saturating with water?

Lord M Vader

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Re: The 2017 melting season
« Reply #1888 on: June 10, 2017, 10:30:22 AM »
ECMWF 00z ensemble shows a very dire situation for the Arctic. The next 5-7 days are extremely bad for the sea ice.

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Re: The 2017 melting season
« Reply #1889 on: June 10, 2017, 11:34:14 AM »
I don't know how much one should trust the Slater forecast for the melting season 2017 as Andrew Slater sadly no longer is with us. However, the forecast is currently calling for a SIE about 6,88 Mn km2 by July 29. While comparing apples and oranges, such a number from IJIS would be only the 7th lowest on record and close to be the 10th lowest(!).

Back in 2012 and 2007, the SIE was at 6,2 Mn and 6,36 Mn km2 at July 29.

The main question now is how big the difference between Slate and IJIS have been in the past? And yes, I'm aware about the fact that Slater did some manual corrections in the past.

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Re: The 2017 melting season
« Reply #1890 on: June 10, 2017, 11:41:53 AM »
The anticyclone may be bringing some sizeable MYI blocks closer to the Beaufort Sea. If I recall correctly last year there were a couple of compaction events at the end of the Melting season, some of this ice is really thick.

« Last Edit: June 10, 2017, 12:36:18 PM by seaicesailor »

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Re: The 2017 melting season
« Reply #1891 on: June 10, 2017, 11:52:38 AM »
SIS: OTOH, the ECMWF depicts a possible weak dipole pattern by the end of the forecast period.

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Re: The 2017 melting season
« Reply #1892 on: June 10, 2017, 12:06:58 PM »
piomas grid been posted many times here.

All displays on a computer screen ultimately use rectangular arrays of square pixels, never curvilinear.


Quite so, but Thomas is relatively new here. I'm endeavoring to explain to him elsewhere what's involved in "go[ing] back to the original numeric data", and consequently attempting to avoid potential confusion.
« Last Edit: June 10, 2017, 01:17:23 PM by Jim Hunt »
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Tigertown

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Re: The 2017 melting season
« Reply #1893 on: June 10, 2017, 01:04:50 PM »
@ Andreas T

That ice looks really thin, thinner than it is supposed to be.
                                                                                                                                 
Below is the Beaufort Sea catching some rays
Blue is the one you see, as it goes deeper through the water before it breaks up. If it is reaching the water, so are the other bands.
How thick is it supposed to be? We don't know how thick this particular area is by any other measurement, all larger areas contain ice of varying thickness and published measurements are averages. The reason I said bottom melt is that the ice must have been thicker when the snow fell on it. The caption says it is near the edge of the ice pack, we know in the Fram strait there is warm water moving in from the south and melting ice rapidly. No one can claim to know how thick this particular floe was 8 days ago.
The other part of your post doesn't make sense to me, what bands are you talking about? Are you talking of ice being blue? Saturating with water?
Sorry, I was trying to make a two part comment about two different things. I thought the divider to be sufficient, but I guess not. Apologies.

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Re: The 2017 melting season
« Reply #1894 on: June 10, 2017, 02:04:46 PM »
Jaxa sea ice thickness image has and is showing a big lump of very thick ice at the pacific end of the CAB. From whence it came?
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Re: The 2017 melting season
« Reply #1895 on: June 10, 2017, 02:31:01 PM »
Jaxa sea ice thickness image has and is showing a big lump of very thick ice at the pacific end of the CAB. From whence it came?

Artifact.

In my opinion, these thickness algorithms over thickens ice significantly when winds are compacting it.

First attachment is June 1-9 jaxa thickness

Second attachment is vector wind anomalies from June 1-7, I couldn't plot the last two days, but I assure that strong easterly winds are present over North Alaska and the surrounding seas.
« Last Edit: June 10, 2017, 02:43:13 PM by JayW »
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Re: The 2017 melting season
« Reply #1896 on: June 10, 2017, 04:11:42 PM »
A-Team quoted a just released paper:

The combination of storms and shallow Atlantic Water both in winter and summer induced large ocean heat flux of order 100 W m−2 in the upper ocean associated with massive basal sea ice melt events. This highlights the importance of predicted increased storm frequency in the Arctic that could erode local stratification and tap into warm subsurface Atlantic Water. In winter, this would lead to reduced growth, weakening, and even melting of the sea ice, while in spring such events would accelerate the melting and breakup of the sea ice. The warming and shoaling of the Atlantic Water inflow north of Svalbard and in the Barents Sea combined with increased storm frequency could lead to a significant reduction in sea ice cover further along the Atlantic Water inflow.

This is why summer storms on the Atlantic side can cause rapid destruction of ice but summer storms in the Beaufort and north of the CAA will cause preservation of ice. The dispersion of compacted ice which sits over a dome of cold melt water in the Beaufort cools off that side of the Arctic. In the summer of 2013 there was a storm north of the CAA that dropped temperatures and put a halt to the melt season over much of the Arctic ocean.

What's going on below the surface has a big effect on what happens to ice when storms move through the Arctic. So far this melt season the storminess has been mostly in locations on the Atlantic side favoring ice melt while high pressure has ruled over the Beaufort, favoring ice melt.

Heavy snow and cool temperatures over northern Siberia have been the one factor keeping the Arctic cool and it's finally melting out now. If storms don't hit the American side of the Arctic ocean in the next 2 weeks we could see a June cliff like 2012.

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Re: The 2017 melting season
« Reply #1897 on: June 10, 2017, 04:29:45 PM »
foehn wind north of Greenland is producing 8 to 9 degree temperature is the from just above ground level to 1.5 km up. With above zero temperatures over near half of the CAB at this altitude and significant tpw and rh starting to get right into the centre of the basin, Atmospheric energy transport looks to really be ramping up and I suspect there is significant rainfall happening over parts of Greenland and Svalbard. And perhaps the caa.
https://earth.nullschool.net/#2017/06/10/0900Z/wind/isobaric/850hPa/overlay=temp/winkel3=324.67,90.87,666/loc=-31.031,84.402
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Re: The 2017 melting season
« Reply #1898 on: June 10, 2017, 05:03:54 PM »
foehn wind north of Greenland is producing 8 to 9 degree temperature is the from just above ground level to 1.5 km up. With above zero temperatures over near half of the CAB at this altitude and significant tpw and rh starting to get right into the centre of the basin, Atmospheric energy transport looks to really be ramping up and I suspect there is significant rainfall happening over parts of Greenland and Svalbard. And perhaps the caa.
https://earth.nullschool.net/#2017/06/10/0900Z/wind/isobaric/850hPa/overlay=temp/winkel3=324.67,90.87,666/loc=-31.031,84.402

My understanding of airborne humid energy transport is a bit limited, but I think you just told me that the Maritime Climate just arrived for this year.

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Re: The 2017 melting season
« Reply #1899 on: June 10, 2017, 07:21:11 PM »
foehn wind north of Greenland is producing 8 to 9 degree temperature is the from just above ground level to 1.5 km up.

That has created some melt ponds today in the fjords on that coast (the darker blobs are cloud shadows). Note the loss in land snow cover over the last 5 days. The loose ice is being pushed away from the coast with the wind but doesn't show particular signs of melting.