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Messages - F.Tnioli

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1
Arctic sea ice / Re: The 2020 melting season
« on: June 27, 2020, 10:32:52 PM »
So far temperatures in Siberia haven't been as hot anymore as before the fire season started in earnest. I wonder if that's just a coincidence, due to the weather, or if the smoke is causing a temperature drop. It would be logical that if we had high temperatures because of clean air, that dirty air from all that smoke would lower them again. If they stay lower than they have been pre-fire season, this could be another negative feedback loop, no? Not that these fires will do any good long term, or for the melting season as that black carbon gets dropped on the ice, but what do you think? Is smoke from more extreme fire seasons a negative feedback loop?
It is without any doubt negative feedback short-term - "then and there". Cleaner air means hotter surface, while air with more particulates of any sort (smoke, aerosols of all kinds, clouds, what have you) means cooler (than otherwise expected) surface, "then and there".

That said, forest fires in Arctic itself cause more than just "make lots of air dirty again". Those throw up serious amounts of GHGs, too - i mean high local concentrations of those gases. Something which is not done by "usual amounts of aerosols" travelling to the Arctic from NH's industrial belt: those come with GHGs already dilluted down to pretty background GHG levels. And, as you mentioned, soot on ice is another, if "a bit delayed", effect.

And then there are of course many other differencies between "industrial aerosols" and smoke from forest fires, as well, which are presumably not as strong as above ones but still significant enough to worth a mention at times. Like, for example, lots more black soot in forest smoke than in industrial outputs due to way more efficient (than just burning some wood in open air) combustion of fuels which industries perform, and lack of any soot-filtering equipment over forest fires (obviously). Black soot absorbs way better than most other aerosols, resulting in generally more heat trapped within troposphere which then has further (mostly unpleasant) effects for sea ice further into melt season. Etc.

2
Arctic sea ice / Re: The 2020 melting season
« on: June 21, 2020, 12:09:22 PM »
I have doodled a thin line demarcating ice that is highly vulnerable to export under normal conditions, and a thick line containing ice that can potentially be exported under extreme conditions (and including Nares). ...
Putting similar lines on last frame of Aluminium's 14-18 June update is perhaps slightly more enlightening, so here goes:


3
Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 05:30:16 PM »
A June cyclone is very different from an August cyclone. August has weak ice, warm water and not much sun, ideal conditions for a cyclone to cause immense damage without paying in lost insolation. In June conditions are very different, thus IMHO GAC designation should be reserved for August.
Different - yes. Very. But anyhow so much weaker in terms of ice-killing effects as to deny it "GAC" classification? Hell no.

Consider:

- any cyclone that strong wipes out remaining high-albedo snow cover really well, no matter how thick's the ice, and there is still month+ of very high insolation to follow. Direct result of such a GAC during said month+ following? Plenty extra ice melt, which effect is nearly absent for an August GAC;

- any and all "lost" insolation is in fact not lost at all, rather, it is absorbed by GAC itself. Fortunately, only a fraction of that energy will end up reaching the ice; unfortunately, GAC cloud masses tend to have much lower albedo than "best case" June's fresh-snow-covered sea ice; and unfortunately, much more energy from insolation GAC itself absorbs in June - could intensify the GAC itself, i.e. stronger winds, higher temps, etc (in compare to same GAC in august). End result? Comparable to direct insolation energy transfer to the ice, exactly because it's June (max insolation) and not August (low insolation, plenty energy lost in stratosphere due to low average sun angle over horizon);

- whateever mechanical / wave-action damage is done in June will have consequences for the rest of the season. While in August, whatever parts of "weak ice" end up grinded by the storm to open water state - those parts will not "suffer" any more in terms of further ice lost, since they are already 100% open water.

I.e., June GAC is very possible given specific circumstances. I'd say most important is mechanical integrity of the ice, which in this melting season is cleraly much lower than even "recent average" (like 2010's average). Pretty sure we can be very (unpleasantly) surprised about what this emerging could-be-a-GAC can do.

Oh and about naming. I wouldn't name it "the GAC 2020", because i deem it quite likely we'll see more than one GAC this season. Possibly ~5 even. Thus, how about "GAC '20/1" or somesuch.

4
Arctic sea ice / Re: Arctic energy balance
« on: May 30, 2020, 06:38:39 PM »
Re-emission will not necessary be at the same wavelength. Energy may stay in the atmosphere for a time but it means more back radiation to surface. Suitable wavelength exists for any height. Convection tends to warm up upward. Radiation is isotropic.
Radiating - is isotropic. Radiation, as in "the process of energy transfer over distance by means of infrared emissivity", though  - is not entirely isotropic in this case, which was whole point above. Mean free path "upwards" is a bit longer than mean free path "downwards" for IR in general. For wavelengths with said path being short relative to air layer in consideration this leads to significant effect, which affects IR overall.

It's like liquid - say, a river - "preferring" to flow towards lower grounds. Except in this case, IR "prefers to flow up". Sort of. Can't put it any simpler.

And about same wavelength, - the spectrum is quite static, actually, and is defined by air temperature, only. You may find some quite surprising details on this page if you're interested about "how it really works". Great read, IMO.

5
Arctic sea ice / Re: The 2020 melting season
« on: May 30, 2020, 06:01:04 AM »
Yes, must be earliest, and by far. Locals noted that near Dudinka, ice breakup in 2020 was May 16th, close to midnight local time, thus breaking previous record (1997, May 21st) by 5 days. In 2019, solid river ice was still present for some 1100 km distance from the place, for May 16th. They also note that Yenisei ice this year is unusually thin, too.

6
Arctic sea ice / Re: Arctic energy balance
« on: May 30, 2020, 05:09:35 AM »
I think, 7...8 km upward is harder way for photons than 0...1 km downward.
...
I think you think wrong. See, it depends, if to be precise, on what kind of IR photon we talk about. Some IR photons will get absorbed and not re-emitted after travelling merely 30 cm through near-surface air. Many others will suffer same fate after travelling merely few meters. Like i said above, "re-iterated great many times by IR exchanges". I said above this gets complicated, right? Can't be helped. Physics.

Yet some other IR photons will freely travel both down to surface _and_ through all the 7...8 km above (actually, all the way to space). And of course, there are yet other kinds of IR photons which on average gets absorved every few dozens meters, every few hundreds meters, every few kilometers - all kinds of 'em. Depends on wavelength - IR photons are actually very big and diverse "zoo".

You can see table 1 on page 1526 of this fragment for confirmation of the above and some further detail. Oh and that same table 1 also perfectly illustrates my above words about air density playing a role within 1-km column in troposphere: as you can see in the 2nd half of that table, at 150 mb mean free path of an IR photon with wavelength most easily captured by specificaly CO2 moleculae - is massively higher than at surface (1st half of the table).

So you see, this whole deal is exactly _why_ i was assuming, initially, that we're talking 1-meter-thick air layer. If it's just 1 meter, then some napkin energy transfer via IR can be calculated; but for 1-km, with those "short mean free path" kinds of IR photons requiring on average thousands (because omni-directional each time) re-emissions? Nope, this gets more like liquid dynamics than anything else, meaning it's not doable on a napkin in general. I think.

7
Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 03:37:53 PM »
Under "assumptions" i meant this line: "This energy may be received by ice or dissipate into space. Both ways are probably significant". Not the numbers. Sorry for being misleading about it initially. See, the assumptions in this line - i think are far insufficient, as per my larger post above; not detailed enough even for napkin calc of the kind.

As for numbers you just noted, sure, you already mentioned in melting season topic that numbers you used initially were far from warmest / wettiest event of the sort. The strongest ones would do well over 100 km3/day ice loss by your initial napkin math, i recon; do your observational efforts confirm this magnitude of melt from those athmospheric fronts, though? I doubt. But if you say they do, i'll pay attention for sure.

added: oh and about 7 kilometers of greenhouse effect on top of near-surface 1-km-thick layer of the athmosphere: it's more of a sink than insulation, i think. Gets seriously colder with altutude in the troposphere. Soaks lots of heat into itself.

8
Arctic sea ice / Re: The 2020 melting season
« on: May 29, 2020, 12:13:14 PM »
My assumptions: 1 km x 1000 km x 5 m/s of air, 1 kJ/ (kg * °C), 1.2 kg/m3, 10°C, 10 g/m3 of water vapor, 2.3 MJ/kg. I saw warmer and wetter events. Infrared radiation provides effective interaction between snow/ice surface and wet air mass.
1 km x 1000 km - this is both horizontal dimensions of a front, with 5 m/s wind speed? What about thickness of it then - 1 m? If you'd elaborate a bit more, i'd be grateful for sure.

P.S. For clarity and lurkers, let's note here that 1 kJ/kg*K is air specific heat; 1.2 km/m^3 is air mass, rounded, per m3; 2.3 MJ/kg is specific latent heat of vaporisation of water, which is released whenever vapor turns back into liquid. There is also 334 kJ/kg, which is latent heat of fusion of ice - the amount of energy it takes to melt 1 kg of it. And, of course, 50 km^3 is no less than roughly 50,000,000,000,000 kg of it (50 trillions kilograms).

9
Arctic sea ice / Re: The 2020 melting season
« on: May 27, 2020, 10:36:15 PM »
...
I have a question for anyone here regarding the importance of continental snow levels in evaluating the sea ice situation. My simple interpretation is that they are an indicator of continental albedo. Lower continental albedo means the land can heat up more and has increased potential to contribute heat to the ice via warm air advection (WAA). Do others see it the same way or is their more to the connection between continental snow and sea ice?
Oh yes, there is more. Much, much more.

Imagine you try to hit a nail with a hammer, but hit your finger instead. Then you ask: what's the importance of my finger being hit by this hammer? Is it that the nail nearby was a bit shaken by the impact of this hammer hit - by the shockwave spreading through my finger and into the board and through it, into the nail? Why, certainly, there is that. But much more important thing is - IT HURTS!!!

Right? :)

Well, same deal with snow cover going away that much earlier. The hammer is sunlight. And the importance of this sunlight wiping away all that snow - is that that same sunlight also hammers the sea ice. Directly. Massively. It melts it. If the snow is gone, then we now it's mainly Sun to blame.

Why look at snow and not at the ice? For the time being - this part of melt season - it is simply so much easier to see the impact exactly on land, because snow is white, while land under it is dark. While ice under snow which was over that ice - is not dark, it's white.

By estimating snow cover in areas directly adjucent to ice-covered areas especially vulnerable to melt during this time of melt season (regarding temperatures, how high sun is over horizon for how long every day, thickness, etc) - first and foremost we can see, with high degree of confidence, how much melt is likely to be happening to snow cover of sea ice and sea ice itself. Everything else - is secondary.

Secondary effects can pile up longer-term, of course, and yes, heat content of air masses is one such thing. Warmer and earlier river runoff is yet another. Possible regional methane release, already mentioned above, is also one - by the way its GWP over 1 year is ~120 of CO2; over few weeks / months? Hundreds times higher than CO2, so any serious release is no joke. Yet another consequence is that further insolation will likely heat up that dark soil well above 0C, - while areas still covered by (by then melting) sea ice will remain near 0C, thus often helping to intensify winds, with further consequences for the ice.

But again, all those are relatively small deal. Insolation is "the" thing to be looking for in June (and near it). Particularly this year, with cleaner air - which intensifies things. To the point it, kind of, "HURTS!!!".

<Great post, removed one word. O>

<It is in my country's culture to keep such words in when emotionally fit, despite obscenity. Apologies... F.T.>

10
Arctic sea ice / Re: The 2020 melting season
« on: May 25, 2020, 12:01:22 AM »
It's so insanely warm (relatively speaking) in Utqiagvik today! Not the mention the amount of melt ponds on the landfast ice appeared almost instantly. So too did the melting of the lake. Wild!


Timely indeed.

Hey Friv, you hear this? Melt ponds appearing almost instantly. I told you it will happen in 2..3 weeks - exactly 3 weeks ago (this post), when you said it'll be in a month. See, things go wild this time, you see what happens with albedo and i bet you know how it goes.

Think Slater's right?

11
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 09:47:50 PM »
   Wow, if that forecast verifies, then 2020 would be 600K and 8% below the previous records for July 13 Extent in 2019, 2016, 2012. 

    It is useful to have Phoenix provide a skeptical check on habitual ASIF catastrophism (as in "this year is the big one!"), but it is also true that 2020 has come out of the gate strong, and that the current Extent and Volume numbers do not yet reflect the preconditioning that has occurred.  In addition, the current GFS forecast shows surface temperature for most of the Arctic Ocean above 0C from May 29 - June 3, combined with substantial areas of clear sky and what seems to be high amounts of precipitable water along the Atlantic front and north of Greenland (but I lack the historical perspective to interpret the precipitable water forecast).   

    I worship at the church of the long term linear trend, which has the 2012 volume record remaining intact for 2020 but then a ca. 50% chance of falling in 2021, and increasing each year thereafter.  For Extent, the trend estimate shows the 2012 record being safe for 5-10 years.  While it is far too early to say anything definitive about 2020, considering the recent conditioning, the current GFS forecast, that scary albedo graph, and the Slater model forecast (which has been pretty good in recent years), 2020 seems to have a greater than 50% chance of going below the 2012 volume record.  The Extent record from 2012 was due to a freak event (the GAC) that is unlikely to be repeated in 2020, so is less likely to be surpassed.  But that is less important anyway, as I also worship at the church of Volume vs Extent with the Rev. Juan C. Garcia.
While i disagree with some parts of your post, i really enjoy it in whole, such a fair and straight one. Thanks for writing it!

Why sure, that nose-diving line is wow alright, yes? Except me, i'd be more "wow" if it wouldn't end up something like that line, this season. But anyhow, "we'll see" and all.

A "skeptical" check requires rationality. Rationality in our here case, as rightfully mentioned by you, means acknowledging that we have preconditioning that has occured already; it's quite a big deal / scale and can not be ignored. Thus, a sceptic would find some rational way to demonstrate how/why such preconditioning would not nesessarily result in "ASIF catastrophism", if to put it using your term. I like the term btw, the irony... Anyhow, ignoring said preconditioning is therefore not sceptical, see. It's merely dumb. That's all it is.

Worshipping linear trend church will do no good, i'm plenty sure. I mean, even simplest check of sure-deal historical data of any kind - be it Earth glacials, or sea level, or temperature, what have you - shows how things have changed in all kinds of non-linear matter, whatever time scale you pick. Why things would suddenly start to work "strictly linearly" now? It's easy to go check this kind of data out, and worth an extra look for "linear church" fellow in particular, i'd say...

And about 2012's freaky GAC - it sure was that, but since then, plenty things got substantially more melt-encouraging. Like GHG air content, big drop in multi-year ice, etc. So now, it'd take way less than 2012's GAC to repeat the same amount of melt. Especially with cleaner air this time, due to big-time reductions in fuel burning around the globe at the time, and its implications to clouds, precipitation, near-vertical surfaces' wettening / melt, etc as discussed above in the topic.

So if we'd want a bottom line for now? "All bets are off" i'd say. We're entering unknown waters now in terms of this melt season. Pun, sadly, intended.

12
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 01:08:43 PM »
... Huge leads in places where we know 2019 gets to zero or close to it are almost meaningless, especially in peripheral locations like Baffin and Hudson.
...
Incorrect. Unusually faster melt in peripheral locations can often indicate faster melt in high Arctic, which would happen later in a melt season. Whenever cause(s) which resulted in much faster peripheral melt early in a season would largely persist through the whole melting season, and we have a number of such indeed, for 2020.

... Baffin, Hudson, Laptev and  Kara combined are ~ 500k km2 ahead of 2019 and is offset by Bering being ~ 60K behind 2019. Knowing where 2019 ends, we know that 2019 is going to catch up at least 400K in these seas. The current 100k lead is vapor.
....
My bold. I believe that the two statements i enhanced with bold text - can not be true simultaneously. Those seas are either 500k km2 ahead - or 100k ahead. I am surprised to see such "wordplay" in this topic. I think it has no place here.

...
On the whole, 2020 has work to do to put itself in position to be a favorite to surpass 2019.
My italic. On the following graph, we can see how 2012 did ~1800k of such "work" between 23rd May (at which date 2020's line ends on this graph) and September minimum. See, by 23/05, 2012 was ~1000k higher than 2019, but at the minimum 2012 was ~800k lower than 2019. Which number - 1800k - dwarves numbers you gave, and in my opinion, proves your whole point wrong:



So, 2012 is one good "hindsight" about how much melt work a season can do. One can easily see how much lower-than-2019 this melting season can end up, if it'll just do "same amount of melt work" 2012 did, while "starting" from today's much lower than 2012's extent (and thus, roughly, also much lower-than-2012's area).

Given those facts, can you please elaborate what was, exactly, the meaning of your statement i quoted (the one in italic right above)? How, exactly, this statement helps us understand this melting season? What's its "meaning", exactly?

13
Arctic sea ice / Re: The 2020 melting season
« on: May 16, 2020, 09:44:22 PM »

...
Is this normal? ...

Perhaps the reduced aerosols are contributing to the reduced cloud cover more than would be expected.  I don't know much about the specifics there but maybe the relationship between aerosol density and cloud formation isn't linear or continuous.
Alright you bozos, i'm sorta back. Must comment on this one!

There is no "perhaps" about it - it's a certainty. Most collegues do not expect the effect as they are not well familiar with papers akin to one i linked in this topic few pages above - about how aerosols affect athmosphere, and clouds in particular. One with plenty links to other ones, i mean.

Long story short, the "big" thing in the room about aerosols-affecting-clouds - is simple: the more microscopic solid particles inside clouds - the more condensation locations are available; so, same amount of water vapour which particular cloud contains - ends up condensating into more droplets (than without aerosols present). More droplets from same amount of vapour means smaller droplets. Smaller droplets means less precipitation occurs = i.e., more of the cloud remains in the air.

Of course, many other things also happen, but i'm quite sure the above mechanism is much more powerful than all other processes caused by reduction in aerosols.

As my remark above in the topic mentions, instruments confirm Arctic-wide overall aerosol reduction. It's so significant it can easily be eye-balled by comparing things like SO4 levels across CAB for same dates of this and previous years.

So - yes, sure, we have, and we will continue to have during this melting season, way less clouds - overall - than normal, unless something exceptionally strong would bring in much more water vapour into the Arctic than during previous years, of course. But then again, that would probably mean helluva lot extra heat coming in as well. Which, combined - heat and water vapour - would mean GACs going through, which summer-time spells doom for the ice no less than sunny skies.

14
Arctic sea ice / Re: The 2020 melting season
« on: May 09, 2020, 12:28:07 AM »
...
uni-bremen are kind enough to continue to provide the service as other information may be inferred from the data...at the user's discretion
"Service" from "stopped" SMOS?

This is a recurring problem of this page: terms. "SMOS stopped" does not equal "does not produce meaningful results". "Other information may be inferred" does not equal "does not produce meaningful information". "Melt ponds confuse sensors" does not equal "wetness of the surface confuses sensors".

Since we're talking about, i'll note that from what i know, SMOS growing error in April has little to nothing to do with "melt ponds" nor with "wetness" of ice surface itself. Instead, the main problem is increasing presense of fog and thin clouds [Yu and Rothrock 1996]. This does not mean April and May SMOS data is "meaningless", however. It means different, more complex approaches are needed in treating raw data to have still useful and precise enough results. Specific data products having a cut at April 15 do not nesessarily mean all data products are stopped. The picture i gave as an example - is a kind of a data product itself, and is indeed useful for easy eye-balling of thin ice right now, in May.

Please note, i am not asking to explain every little detail in this topic. I ask to use non-contradicting terms. Like, instead of "melt ponds confuse sensors" - say, for example, "technology limitations disallow reliable total Arctic ice volume measurement after mid-April based on those sensors". Like, instead of "SMOS stopped" say "SMOS measurements stop being used for calculating total ice volume mid-spring due to growing measurement errors which currently we're unable to remove". Etc.

If we'd be failing to avoid "contradicting per common sense of a non-scientist" statements here - even when such contradictions are in error de-facto - then what exactly this topic is for?

15
Arctic sea ice / Re: The 2020 melting season
« on: May 08, 2020, 05:53:27 PM »
F. Tnioli, a gentle warning: I will not tolerate hints of lies, conspiracies and the like on this thread. There is a perfectly good explanation, and lying by ice scientists is not it.
In addition, I've requested that DMI volume discussions take place in the appropriate thread.
Will you tolerate this thread saying "there are no melt ponds in April" and also saying "no data from CryoSat-2 for 2nd half of April because meltponds confuse sensors"?

If the answer is "yes", i'll see myself to the door voluntarily. If the answer is "no", then i ask to forgive me for probably inappropriate way used to describe the problem.

DMI's realiability or lack of - was not discussed. I merely mentioned couple things about it as relevant to discussing "melt ponds in late April confused CryoSat-2 sensors" line, which line is the thing i discussed. DMI graphs are welcomed here for what - to ignore them? I am confused. For now i'll simply avoid doing _any_ mention of DMI results / data, then.

In any case, please feel free to snip this and/or previous post of mine any way you deem good for this topic, up to and including complete removal. I will never hold any grudge towards you, Oren, no matter how much my opinion may differ from yours at times.

16
Arctic sea ice / Re: The 2020 melting season
« on: May 04, 2020, 09:23:26 PM »
As if 1050+ is not enough to be one helluva big story, though. Especially for May. Lots of places would see it as highest-ever in well over a century of observations, like, for example, Iceland.

17
Arctic sea ice / Re: The 2020 melting season
« on: May 04, 2020, 07:47:55 AM »
2-3 weeks is what i expect, Friv. Not 1 month. Cleaner air, you know. Instruments confirm, overall Arctic.

18
Arctic sea ice / Re: The 2020 melting season
« on: May 03, 2020, 03:14:55 PM »
... Not sure what kind of weather pattern can cause this and what the probability is for it to remain sustained for a long period. ...
Why, we can see it alright. Quite a pattern indeed.

Day 68 is early March, and we had "positively persistent, persistently positive" AO at the time, as conviniently reported exactly in early March on this page.

So i took a quick look and it seems we had up to some 25 km/h winds exactly "between Pole and Greenland" at day ~68, surface level:



Importantly, this was very wide wind field, as you can see. Looks like ~25% of CAB ice was pushed sough and then south-east by those winds, which push mounts to huge pressure, i'd imagine, given how large area this wind was working against. Which usually doesn't do much in winter because ice holds structurally. But i think this time, it snapped under the pressure near that day 68. It'd probably still remain mostly stuck, but ~4 days later, this started (and lasted for a few days):



Given your numbers, which mean some ~0,5 km/h drift speed average for those 37 days, and given this wind speed - that drift does not surprise me the least.

I also checked same (or very close if no data for exactly March 8th is available) all the way back to 2014, and not a single year had anything similar even to 1st picture, normally it's smaller much more wavy winds much within CAB itself; and especially nothing even remotely close to the 2nd picture.

P.S. It was also then and there we had that massive ozone hole present. I read most stratospheric ozone was gone. The gas absorbs / traps IR really well, so when there is little of it and no sunlight to speak of, big temperature gradients form up. Ergo, stronger winds. Which we exactly see per above.

19
Arctic sea ice / Re: The 2020 melting season
« on: May 02, 2020, 02:50:42 PM »
... Seals do NOT crawl onto the ice where polar bears "can hunt them"!
...
They do, see v=zNO0kxTClYo on YT. However, i'm much more interested to know what you think about my above hypothesis of sunlight actually adding some melt water whenever irregular ice/snow surfaces are present. I agree with others when they say it'd be highly unusual to see melt ponds forming now, but then i also see highly (pun intended) unusual temperatures in March on Atlantic and Siberian sides, too:



I wish we could just ask good gents on Polarstern to go out and check if snow/ice is any wet when it's sunny around the ship. I know satellite sensors can pick up liquid water even when it's not in distinct ponds, but mixed with snow on top of ice. Could be one big part of those "strangely little ice" images posted above, me thinks.

20
Arctic sea ice / Re: The 2020 melting season
« on: May 01, 2020, 11:06:36 PM »
Me neither, Neill. ;) Perhaps it rained, perhaps moisture, perhaps clouds. Let's see if we hear something from the Polarstern.
...
This photograph, i believe, was created from Polarstern's bridge ~3 days ago, 28th April:



Can you see the bear? Anyhow, from the accompanying note posted at nasa.gov, we can read that the bear is, quote, "standing behind Met City near a small lead, likely waiting for a seal". Earlier in the note, we also read that bear, quote, "... sat near a small crack in the ice for almost two hours, likely waiting for a seal to surface".  Seals, i understand, would need open water to come onto the ice, where polar bears could hunt them. So, it seems there are some areas of open water per the above - and it looks like at least some of such openings do not freeze up any much for ~2 hours. I don't think bears are that stupid to spend some hour+ hunting a piece of any significantly thick ice, are they?

Much more importantly, however, is shape of sea ice which above picture presents. As one can see, ice in this particular area is abundantly uneven. With Sun being low over horizon for the time being, this creates really long shadows, clearly visible on the picture. Yet surfaces which are _creating_ those shadows - are often nearly vertical, and thus they absorb lots of sunlight. I think those surfaces are wet, - now that air is much cleaner than in previous melt season, very long path it takes sun rays to go through the athmosphere (because Sun is so low yet) does not deplete energy of sunlight anywhere close as it did previous seasons. Like was mentioned couple pages ago, one can easily see from Finland shore all the way to Estonia now - visibility is _times_ better. Same story would mean times higher W/m2 hitting those "bumps" on sea ice, per above picture - and wet them up good deal even while overall 2m tempeatures may be at -10C or even lower.

And we clearly see the area was quite well lit as of 3 days ago, too.

If someone has any better explanation than above, then please share.

21
Arctic sea ice / Re: The 2020 melting season
« on: April 30, 2020, 10:41:41 PM »
Hmmm... 🤔
500 km3 of ice gone in last 10 days of April, eh. If this what's going on, then things melt as if it was last 10 days of May, not April. Like lengthening melt season by 1 month, sort of. For BoE, "extra 3 weeks" should suffice if one would do some silly numbers on a napkin based on what we saw in 2019. Could be we're starting to see even more melt power than anticipated per some above concerns, Pinatubo and all. Please keep 'em volume graphics coming if possible once a week. Few more weeks should tell us helluva lot of story already if this pace would continue.

22
Arctic sea ice / Re: The 2020 melting season
« on: April 29, 2020, 02:33:37 PM »
...
It will be interesting to see if area drops below 2016 over the next few days, which considering how much vulnerable ice there is in peripheral seas, shouldn't be hard.
Interesting indeed, but needs to be observed in conjunction with data about ongoing cloud cover (or lack of) over said peripheral seas. There are two factors we expect to play a big role in the process - vulnerable state of ice and clean air, and yet they both are minimized when/where there is no sunlight present over any given peripheral sea, roughly speaking. Thus i'd say it's not just "if" area drops or not, - it's "if" area drops in those seas which are any well soaked in direct sunlight.

And to me it's also very interesting to see if we'll have more such areas than usual. Current weather / vortex effects of course overrides, but there is now that general effect of way less nuclei in clouds - so bigger water droplets / snowflakes, means precipitation should deplete clouds faster.

23
Arctic sea ice / Re: The 2020 melting season
« on: April 28, 2020, 10:31:38 AM »
...
* Personally-charged comments and slights of honor should be avoided (even when justified...), ...
Gentlemen - everyone! I ask us all to note the above bold / large (my enhancement) words and always remember them. At _all_ times.

I thank you, Oren, for putting it this way. This will allow us all to remain professional, here. Please strike down anyone violating this particular part - "even when _justified_" - without mercy. I think this is the greatest part you just did, for this topic!

24
Arctic sea ice / Re: The 2020 melting season
« on: April 28, 2020, 10:25:46 AM »
We have seen a massive drop in aerosols and the conversation preceded this post further discussing the impact of contrails.

I think Freegrass is correct. The aerosol problem this year is unprecedented. A page or two back, or it may have been another thread, someone posted that we contribute roughly 8 Pinatubos of SO2 a year to the atmosphere. What will the impact be of one less Pinatubo a year? Or two? Or three? Or even four? The best case is we have two "reverse Pinatubos" the worst, is probably three or four. That is a recipe for absolute catastrophe in the Arctic, especially when you compound it with the impact of contrails / etc.
You probably refer to this post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261429.html#msg261429 , in particular its paragraph following "3." one. And while "absolute catastrophe" is not likely to happen - i deem "absolute catastrophe" being the state when Arctic ocean top layers stay much above freezing point 24/365, like it was in the past when crocodiles lived there, - i concur that this melt season is likely to mark the beginning of the shift which will eventually lead to such a state. Huge thermal capacity, you know. Will take more than one or two summers to get there.

Obviously, melt ponding will be our early indicator of how dire a situation this melt season is likely to end up being. Extra attention to melt ponds, with perhaps finding new methods to quantify melt ponding better than we were able before, would very much help.

25
Science / Re: Contrails & artificial clouds
« on: April 27, 2020, 04:17:22 PM »
Recent conversations in the general melting thread have brought up the subject of contrails. And in particular what effect would reduced air travel have on global and/or Arctic temperatures.

I couldnt find a more recent thread specifically on contrails and didnt want to mix it up with the aerosol thread which is a bigger topic.

Most of the literature I see out there say that aviation-induced radiative forcings (CO2, nitrogen oxides (NOx) and contrail/cirrus cloud formation) have a net warming effect. . NOx creates ozone and destroys methane and is a net warmer. As are the contrails and resultant cloud formation which trap radiation escaping from the Earth.

It's not all one way traffic though and this study in Nature found that contrail cirrus cause a significant decrease in natural cloudiness, which partly offsets their warming effect.

https://www.nature.com/articles/nclimate1068

So in reply to F.Tnioli post in the melting thread, would the reduced aircraft over the Arctic have a slight cooling effect overall ?
The way i see it, whenever insolation is close or at 24/7, incoming radiation is much higher than what Earth surface is able to "bleed back" to near-Earth space. Thus sunny places like equator are hot, ain't it. So during polar day, clearer sky - in particular, less contrails, - is definitely major warming of Arctic surface layers. Much of the summer, as we all know, insolation in Arctic is higher than even at the equator. High albedo slows the melt, of course, and it's a kind of balance which can and will be affected.

To me it's in general that simple: contrails are a sort of insulation, and as such it works both ways. I.e., slows down both cooling and warming: whichever would naturally happen given no contrails are present - would still happen, just slower: the more contrails, the slower temperature change will happen on average, if we speak the surface of Earth, that is.

As since for most of this winter we had "normal" amount of contrails over Arctic (let's not forget they don't entirely dissipate same day flights stop happening, far from), there was "slower/less cooling than it'd be without contrails" for freezing season, thus resulting in less ice thickness, weaker ice, warmer ice temperature on average, etc; but now with contrails gone, this "weak freezing season" - weak as is in compare to the old days, pre-1980s, - will be followed by "stronger (than recent years - with plenty contrails)" melt season.

So, before someone drops a vial with some coronavirus 2.0 - please tell 'em to wait about doing it all the way till NH summer, right? This way next "no contrails" season will happen in NH winter, clearer skies = more freezing. Then at least it'd be somewhat good for the ice outta next outbreak of the kind, eh...




26
Arctic sea ice / Re: The 2020 melting season
« on: April 27, 2020, 10:28:15 AM »
I took a bit of time to verify if my above concern about jet contrails now mostly missing from Arctic sky is of any practical significance, and what i found - is yet worse than i throught it'd be. Namely, i found that:

- during recent years, there was continuous jet liner air traffic over Arctic on the scope of many hundreds flights per day by only US air lines, and most likely well over a thousand flights total if to include non-US international air lines flying this North Route, as they call over-Arctic airways;

- but now, ICAO says that in April 2020, global international passenger capacity "so far" suffered 91 percent reduction.

And obviously, most of remaining - for now - 9% of international flights are not between usual sides of trans-Arctic flights: Europe and US are most affected by the virus, so quite nobody would be eager to accept lots of flights from those parts - not now, nor for (at least) a few months forward.

So, this is fully comparable to the 9/11 case of almost whole US jet liner fleet grounded for three days after 9/11, described in that BBC transcript i linked in my earlier post: "During the grounding the temperature range jumped by over a degree Celsius. DR DAVID TRAVIS: This was the largest temperature swing of this magnitude in the last thirty years". Except this time, it ain't for three days, it's for months, and apparently well past May. Which means 0/0 night time. No cooling, only heating up the surface whenever not cloudy.

I tend to value practical measurements of this kind higher than modelling, and so it seems to me absense of jet contrails alone will bring in - over weeks of 24/7 sunshine unobstracted by contrails - _several_ degrees C increase to surface temperatures.

Can't see how anything less can be. With recent years at times quite walking the edge, it seems this time BOE is quite at the door, and possibly with a big bang. If i miss something crucial, please tell. I'd want to...

27
Arctic sea ice / Re: The 2020 melting season
« on: April 25, 2020, 01:12:07 PM »
...
Do you have any stats to back up  this  ? Re cyclones.
I don't, but i did not look for, either. Was just general consideration, which i think is quite obvious: when it's some 10%...15% of sunlight normally much absorved by aerosols, "normally" means with recent-years-typical amount of fuel burning by mankind, - we'll have that much more heat mostly added to troposphere, and cyclones are driven by athmospheric heat. Substract from it, and less "of" cyclones will be around: less number as well as less intensity.

Important also: "less" means "less than would otherwise happen", and with ever-growing GHGs, the general trend is to _more_ of cyclones as years go by. So less aerosols will make it "less than would happen with both normal aerosol content and with normal GHG growth", which does not nesessarily mean "less than in recent years", since GHG growth is ongoing process.

It would surely be very interesting to see how many and how strong cyclones in the Arctic would end up happening, but obviously we're not yet at the point in time when this could be measured / quantified. This is a talk for the end of this melting season - about estimating cyclones' number, strength and effects on sea ice.

The above point about less aerosols present in the air remains game-changing despite the uncertainty about "absolute" number and strength of cyclones / cloudy days during this season, however, because higher actual insolation at the surface - i.e. few percent more sunlight reaching the ice directly, - will still produce greater melt "per sunny day" than in recent years. Especially with less jet contrails directly over the Arctic as per less jet liners crossing the Arctic back and forth, as was usual in exactly recent years. The effect is relatively small "directly", but multiplicated with further albedo feedback, of course - few percent faster melt produces few percent darker surfaces on average, which then add ever growing further extra melt into the picture.

28
Arctic sea ice / Re: The 2020 melting season
« on: April 24, 2020, 07:36:14 PM »
Thank you for the chart grixm. It's worrying to see this year leading in that metric. Though it does appear that recent years bunch together come summer.
I join the tanks to grixm for the graph; much appreciated, and definitely timely per concerns further in this post.

I apologize for somewhat lengthy remainder of this post, but i think this is way too important; like, 2020's "must know" thing for the melting season (and for lots of other things too).

This is in response to the reference of "recent years" by Davidsd. This year is much different from recent years, and much more so than lots of people here could probably imagine.

1. China stopped most of its transport and industries for a fair while, and lots of it - half, give or take - are not back even now. This is now being followed globally: fuel burning by mankind is decreasing by the day, as reflected by oil prices;

2. This means less aerosols in the athmosphere, to say the least. Plenty cities in China were observing the stars clearly for the 1st time in decades, so strong was reduction in air pollution there. The normal effect of global dimming at the surface is quite massive on average over continents, too - over 10%, at places well over 15%, as was discovered by both pan-evaporation measurements, other methods and eventually multi-national 4-year INDOEX measurement effort (some details freely available here: http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_trans.shtml ). In the same piece one can also find summary of findings about direct effect of absense of jet contrails, which was found to be much bigger and more rapid in practice than anticipated.

3. As a result, right now (as well as progressively stronger during last couple months as the situation develops) - significantly less sunlight gets "caught" by aerosols before it reaches surface, which means less of cyclones (direct consequence of comparatively less heat content in the air), so more shiny days on average scale, and faster melt ponding / top melt in the local scale. So far, most of GHG effect - in the Arctic as well as around the globe - was negated by aerosols in this way, and lots of it still is, but the changes are big enough to already be a game-changer as far as ASI melting season is concerned as a whole.

To understand the scale and importance of those effects, it is enough to remind oneself that industrial activities since the industrial revolution have injected nearly 5000 Tg of SO2 into the athmosphere, with recent years being ~7...10 Tg/year - and that famous Pinatubo eruption, responsible for significant cooling of whole Earth's climate, released only ~1 Tg of SO2. Thus, even "modest" 10% cut of aerosol emissions by mankind can produce changes comparable in magnitude to Pinatubo eruption - except not to cooling, but to warming the climate. Further details about how aerosols work and plenty references for great number of good papers - can be seen here: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015RG000511 .

That same piece also describes timescales relevant for aerosols' lifetime in the athmosphere, which depending on type, size and source of a particle will vary from some hours to some months - with everything tropospheric leaning towards much shorter lifetimes (days to few weeks at best, usually) as precipitation washes 'em down to surface.

Same piece also mentions the following processes, to give a short quote here (by bold):

"In the stratosphere, strong zonal winds lead to fast homogenization of aerosols and tracers in the zonal direction, while vertical and meridional transport is controlled by the BDC [Holton et al., 1995; Butchart, 2014]. The BDC results from the breaking of upward propagating waves in the stratosphere that lead to a diabatic residual circulation [Holton, 2004]. The residual circulation is characterized by ascent over the tropics, poleward motion in the extratropics, and subsidence over the high latitudes, in particular over the winter polar vortex, ...".

So, with rather big uncertainties about how yet worse microbiological situation will become in the following weeks and months, but with rather big certainty that lots of intercontinental jet flights over the Arctic are not happening and won't be happening any time soon, i can easily conclude that "recent years" are not a predictor of anything, now.

29
Arctic sea ice / Re: The 2019/2020 freezing season
« on: February 26, 2020, 12:14:38 PM »
...
Northern hemisphere snow distribution is uneven - modest positive anomalies across parts of Siberia and N. America, but significant regions at high latitude in Europe that are currently snow-free with daily increasing heat.
...
My bold. I said it a while ago about "no snow cover during late winter triggers massive albedo feedback", meaning by this significant insolation in February, March and April hitting dark Earth surface instead of white snow. Which brings in - as it stands right now - truly massive extra heat into the system where and when this heat is not supposed to be. Above posted temperature anomalies for large area south of Scandinavia and large parts of Siberia - are mind-boggling to me.

I foresee highly unusual melting season as a result. In particular, i expect great number of strong cyclones entering the Arctic and some, possibly, forming in it much earlier and stronger than ever before. Russian Far East and much of Canada remaining cold while Atlantic side warming up at an accelerating pace (low albedo plus rapidly increasing effective insolation as Sun gets higher over horizon for longer times in more and more places) - will create huge air masses of wildly different temperature, which will sooner or later interact with quite predictable result. Not good for ice, i guess...

30
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 14, 2020, 02:14:46 PM »
Those ponds, together with "Last weeks 7-day hindsight means GIF (anomalies)" posted by Blumencraft just few posts above, confirm one big suspicion i had for this freezing season: namely, the huge winter mode shift for Arctic and subarctic regions. Which shift is more heat and moisture in the system causing more clouds remaining for much of the winter, which clouds then dramatically slow down winter-time heat loss from both the surface and lower athmosphere. Which slowing further massively extends duration and scale of "thickly clouded" areas - a runaway process.

Obviously, any prolonged periods of massively dwarfed heat-loss process in Arctic and adjucent regions - will have significant impact on following melting season(s), but there is yet one much more serious implication: the "albedo connection" as one may perhaps call it. The warmer things are, the less places are snow-covered by the time insolation starts to be a thing again (and the less snowcover's thickness / brightness is there in places which still retain some snowcover, too). Just like ArcticMelt2 just mentioned: "when the sun comes up", which for sub-arctic regions is already pretty much "now" or "very soon".

Right about now, we have much of the Arctic cloudy (good bye, "polar desert", eh), and even some parts of it - between Iceland and UK/Scandinavia - getting few millimeters of rain. If those cyclones would keep coming same way, then together with seriously positive SST anomalies around Scandinavia and all along US eastern coast - then i wouldn't be surprised to see Atlantic side of the Arctic going blue much much earlier than ever before, later this year.

31
Arctic sea ice / Re: The 2019 melting season
« on: September 20, 2019, 01:34:16 PM »
Sam, multi-year dynamics are off-topic here as long as discussing them does not lead to anyhow better understanding of the 2019 melting season. The _topic_ is named "The 2019 melting season", and thus any discussion which does not and/or can not allow to gain knowledge about this one single melting season, in here - is off-topic by definition. This does not anyhow reduce such discussion's own value, of course. The term "off-topic" merely indicates the discussion, however valuable, is not supposed to happen in this particular topic, nothing more and nothing else.

That said, there are indeed some subjects which, despite being off-topic, may be allowed to be discussed in this topic by the board's administration, to some finite length. The one Sark so originally touched - is probably among them. Importance and obvious relation to this melting season are among probable reasons for it to be. However, please always remember that the more off-topic discussion we'd do here, the less compact and "handy" the topic becomes for great many people who come to it for information specifically about the melting season itself. It is, you see, much about respect to other people to limit off-topic discussion here quite much, even if and when there would be good reasons to have it.

IMHO.

32
Arctic sea ice / Re: The 2019 melting season
« on: September 12, 2019, 01:43:44 PM »
...
On that note, how's that multi-year ice doing in 2019?
It's doing exceptionally well: practically all of it is in sea ice's heaven now. Gone to better world, it is. No more suffering from all the greenhouse effect, bottom melt, rains and melt ponds all over it. RIP, MYI.

NASA was kind enough to present 1984-2019 animation about it - see yourself, in which amount of ice 4+ years old is practically zero by July 2019.

33
Arctic sea ice / Re: The 2019 melting season
« on: September 09, 2019, 02:54:50 PM »
If the mercator model is correct slush dispersion doesn't significantly affect SST yet. Depending on the weather, extent may follow 2018's slush path (brown) to meet 2012 (yellow).
amsr2-uhh overlaid at 60% transparency onto mercator SST, aug1-sep6
wipneus regional extent, CAB, sep6
piomas percentage of maximum by year, CAB, 2011-2019
edit:forgot scale
I have a feeling that that PIOMASS percentage-of-maximum graph has too little space on the right side, with - was it? - day 260 being the limit. I mean, my gut says _this_ year the minimum in terms of that particular metric could perhaps happen well past day 260. I wonder if you feel anyhow similar, sir.

34
Arctic sea ice / Re: The 2019 melting season
« on: August 23, 2019, 11:36:59 PM »
... 969 hPa, and in 5 days, if the forecast holds, Svalbard will be hit hard.
I had a feeling it'll be strengthening as we get closer to the date. Plenty energy in the system. Tends to do that. Let's see if it'll end up even lower.

GAC 2019 on the horizon now, no joke. 2007 + 5 = 2012, 2012 + 4 = 2016, 2016 + 3 = 2019 may well end up quite a complete pattern yet, eh. If so, one wonders what will be happening after +2 = 2021 and +1 = 2022. Every year GAC year afterwards? Heck. I wouldn't be much surprised at all...

35
Arctic sea ice / Re: The 2019 melting season
« on: August 23, 2019, 04:52:22 PM »
...
Re: The O/T.
...
Enough O/T, gentlemen, please? And PETM, i've sent you a PM about it, and i eagerly await your reply there. If you'll want to add anybody else to that PM conversation - please feel free. But here, we must stay on this season's details without any significantly big O/T deviations, as you certainly know. Cheers!

36
Arctic sea ice / Re: The 2019 melting season
« on: August 22, 2019, 07:35:28 PM »
HYCOM Ice Thickness August 22 - August 29



I feel like HYCOM must have changed their scale or something because that literally looks like the end of ASI as we know it.
Scale or not, that relatively large patch of while right next to the pole must be something quite interesting. I wonder how that particular place will look like in a week from a satellite, there.

P.S. Oh, and don't underestimate ~0.5m of ice late-season. It'll hold pretty well, especially in CAB, provided weather is not destructive. Insolation rapidly declining is a big help.

37
Arctic sea ice / Re: The 2019 melting season
« on: August 08, 2019, 10:13:06 PM »
Finland has been experiencing record cold the last day or two. I caught this tweet with an interesting chart that shows where the cold air is coming from. If this cold air is moving from the Arctic down over Finland, doesn't that mean warm air could be flowing in from elsewhere to replace it?
Not just Finland. Large parts of Russia are breaking minimum temperature records last week or so. For example, the capital - Moscow - had 4th August top temperature of 13.5C, lowest recorded during past 70 years. Saw reports of massive cold in Norwegia recently, too. Those are large parts - Scandinavia, Russia. And sure, whenever large mass of air leaves Arctic - similarly large amount must enter Arctic elsewhere. Can't be vacuum left behind, eh.

38
Arctic sea ice / Re: The 2019 melting season
« on: August 08, 2019, 02:59:39 PM »
A short 20-second video of a waterfall of melt water near the northern tip of Greenland - in this twitter post. Text in the video says "July 2019". I wonder what is happening in those parts now after days of open sky and high air temperatures...

39
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 04:17:35 PM »
...
2019 definitely appears to be one of the worst years on this date. How bad will this melt season end up compared to previous worst years? Too early to tell?
Yes, too early. I see that unusually large amount of ice is now in the state which allows quick and massive melt under GAC-like conditions, by either low thickness, high fragmentation or both. In the same time i see large amounts of ice which are just barely enough thickness to survive if it'll be not too much wind and not too much insolation. I.e., the season arrived to the point where weather decides unusually much. And since "usual" is already pretty much - yep, too early to tell.

40
Arctic sea ice / Re: The 2019 melting season
« on: July 31, 2019, 01:54:19 PM »
...
Keep on posting stuff like this, Jontenoy. Ignore the ignorance of others.
I support; thank you for posting about 'em blueberries, Jontenoy. We need every bit of anyhow related observation we can get.

P.S. It ain't just blueberries and anecdotal, as it turns out: in Lithuania (not too far), "winter barley matured really early. And it surprised that winter barley matured in the middle of July. I don't remember such a thing over my 20 years of farming".

41
Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 06:36:27 PM »
As of today, the Greenland's highest point surface temperature became above 0C (just 1 pixel above 0C line) and stays there for a few hours already (this is measurement, not modelling). Means even the summit, which is ~3200m above sea level, will see at least some melt despite all the elevation. The amount of heat at lower elevations (and thus melt, and thus meltwater going to do bottom melt to sea ice later on in the season) - will thus be huge.

42
Arctic sea ice / Re: The 2019 melting season
« on: July 27, 2019, 10:57:46 PM »
I agree, for now 2019 seems to be more compacted and hopefully resilient near the pole, same as 2012 and unlike 2016.
Why "hopefully resilient" if we say that near the pole will re-freeze early September, though? If you mean wishing well for arctic sea ice in general, through the seasons, - then it's not much difference IMO. Multi-year ice is pretty much history now, anyway; and winter will refreeze "near the pole" quite very well anyhow - next freezing season, i mean. Far not enough ocean heat content to prevent it - for now.

Meanwhile, as if recent insane temperatures in northern parts of Canada and predicted very strong high over Greenland would not be enough, - we now have masses of hot air from Sahara and Spain heading towards Greenland, they say. It's that same heatwave which killed people in Europe just few days ago which now goes to "visit". Yet even worse its effects will be if that high pressure would then "anchor" itself in the region through self-enhancing clear sky extra heating.

We know it can happen, because it already happened in very similar circumstances: in 2010 over central Russia, about same time of the year (July / August), more than a month of unprecedented heat and clear skies - and in that case air masses came from dry desert lands much closer to the equator, too. Almost choking Moscow and whole regions in smoke from all the fires around, destroying ~90000 km2 of farmlands, etc - saying this just to illustrate how big, bad and long those "stuck" highs can be. Game-changer kind.

43
Arctic sea ice / Re: The 2019 melting season
« on: July 27, 2019, 01:54:56 PM »
Few pages ago, i wrote about my concern about gigatons of melt water going from northern side of Greenland into the ocean, adding to bottom melt of ice in the region. I'd like to have better estimate about how significant this effect is. I checked few places, and i found clear confirmation of the effect in the form of darker shades of green for 2m temperatures over both open water and still ice-covered areas of the ocean adjucent to northern side of Greenland in this forecast - click "right arrow" button there to animate.

A bit of those darker shades of green move somewhat towards the pole (and eastwards) and as far as more than half distance to the pole, at some point, as one can see.

Thing is, those are 2m temps - not SSTs. Means, while warm melt water affects it - many other things affect it also. Thus, i'd like to know SSTs of the open water areas north of Greenland. What would then be the most respected resource which would demonstrate SSTs for the area, either observed or forecasted or both, real-time?

P.S. Checking under-ice topography of Greenland, it's obvious quite many within-ice configurations of melt water bodies and channels will result in much, if not most, of melt water discharge from central greenland to end up running to the ocean through north and north-east edges of Greenland. So, given forecasted and massive snow cover melt i mentioned earlier in the topic and that topography, dozens-gigatons melt water pulse soon after the peak of the forecasted high over Greenland seems quite unavoidable, to me. Anywhere i am hopefully would be mistaken about this all - please tell...

44
Arctic sea ice / Re: The 2019 melting season
« on: July 27, 2019, 12:40:25 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15

Is there any chance to measure sea ice thickness (at least at some points) by ships/expeditions in the CAB and to compare the measured data with the modeled data and (maybe) adjust the models to the reality?
Measure - yes. Compare - no. See, the measurements are being done all the time. Problem is, for some reasons publishing those measurements - is not possible for any modern times. Historical measurements - pre-2000 - are easily available, as mentioned, for example, here.

edit:
I have just returned from Croatia. Thanks to everyone for the condolences. In coming days, I'll try and get things in order here on the Forum.
It is great to see you back and to see your spirit strong, man! But you sound still grim. I understand. Been there, 28 years ago... Please, do always remember: he's not dead yet - as long as you are alive and your memories of him are alive, he is in a certain and very real way still alive. Nothing mystical, pure neuro-biology here. I'm sure you can see how it works if you'd think about it. Salute!

45
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 11:40:45 PM »
...
All that said - we do get consistent and timely measures with equally consistent comparison values for decades of history - we can get wrapped up on daily data variations, but the bigger picture of year over year and decade by decade change is valuable and with all it's limitations seems to be a valid measure of what is happening.
Good discussion. But this particular point, i can't agree with. Decades of history means nothing if you have the system changing its mechanics - not just amounts of this and that. And Arctic does exactly that, especially this melt season, because of earlier and much larger areas of open water during this melt season - if we compare to "decades of history". See, those areas absorb lots of heat which historically was spent to melt ice in those areas - but this season there was no ice to melt then and there, and so that heat warmed up water column instead. And much of it ends up bottom melting more ice - just some place else and quite much later during melt season.

I am convinced amount of this action is both very significant for this melt season, and quite unprecedented anyhow "historically". This year's pacific side was so open so early, etc... We still do not see full extent of all the absorbed heat during last ~50 days, but we certainly see some of it in action now. And bottom melt is exactly the sort least noticeable from above, until things start to fall apart - which then looks very much like that picture jdallen posted, i believe.

Further, warmer water column alters not only ice melting later-on, perhaps even more importantly - it alters weather systems around, thermal gradients near remaining ice, slows or halts any otherwise possible re-freeze processes. You know how land areas around the globe which are near large bodies of water have their local climate "moderated" by such a big water body? Year-round. Well i see no reason for similar effects to not happen in Arctic, and they gotta increase as open water areas appear larger and earlier.

This all exactly invalidates estimates of current situation based on historical measurements. How much it does? How big is the error for every particular date / region / measurement kind? Obviously, hard to tell. But i prefer to err on the safe side of things and limit usage of "historical comparisons", when there are reasons enough to be unsure what are the answers to those questions.

Especially since even largest bodies already made that same mistake, and quite many times. Like IPCC predictions of summer Arctic ice holding up to some 2080s or so, which were official and all-serious not much more than just a decade ago - were much based on "historical comparisons" indeed. I guess you know how different is what was observed and the line IPCC had in that prediction for up to current time? More than humiliating - i'd say, shameful.

So you see, can't quite rely on history anymore. Too fast a change is happening there. The ice desert of Arctic is not quite there anymore...

46
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 08:24:54 PM »
...
So my major doubts are with the US Navy's HYCOM gifs.
...
Jokes aside, sure, doubt is for every model, some more, some less. But there is one thing unique about US Navy's Arctic Ice matherials - which is, those guys actually go there all the time. They can and certainly do verify their model's results with actual measurements. This among other things is also military matter: certain subs have certain limits about how thick ice they can push through, and thus it's important to know where both sides' subs can possibly appear and fire away.

47
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 08:12:18 PM »
HYCOM - Arctic ice thickness (CICE) model - July 26 - August 2

<GIF of shitty model here>


If you're looking at that for an estimate of the pack edge retreat, I give you a pass. If you're looking at the thickness and believing, as somebody pointed out, that the thickness at the NP is similar to the thickness at ESS, we are in serious trouble.
"Shitty model" you say. Science.gov website says quite another thing, on this page. Guess who we tend to believe more: your word, or said page?

This ain't to say we diss you. This is to say we diss your post for the lack of substance. And we'll keep doing so unless you bring unbiased and verifyable arguments to the table. Days when people in this sort of debate had the luxury of trusting ones' fair word - are long gone, sadly.

48
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 02:37:49 PM »
Guys,guys!

We know why Neven is away and you want him to come back to this???

Take a chill pill, kiss and make up .and lets move on please?
Yep, i concur with Gray-Wolf 100%. Everyone just calm down for Neven's sake, please!

P.S. If someone missed what it's about - it's extraordinary circumstances currently, for Neven: he's enduring through much stressful, very obligating and major family matter, at this time. This is what keeps him away and very busy, for now. Lots on his shoulders now, as it is - and we can help by at very least staying civilized in the forum here.

49
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 01:35:22 AM »
Repeating myself, the continuation of the current wave, days 6 to 10 can be evaluated using 5-day average over ensemble of forecast, to fail in the conservative side.
What the EC ensembles say is that the Greenland ridge will be strengthened, and the corresponding high will be strongly reinforced. Not as bad circulation as present, but not party time for the pack either. And a very bad news for Greenland
Hot damn! HOT DAMN! Friv, where are you? We need your writer's talents, sir. Seems this one is quite a fitting occasion...

This is not just "very bad". This may well be total melt of Greenland surface of unprecedented proportions - as well as similar kind of event for sea ice north from Greenland. Hell...

See, 11...12th June, this year, nearly half of Greenland already melted. This means less snow cover and easier-to-melt layers of refrozen snow/ice mix (those always have less reflectivity than proper snow - so lower albedo). Back in those days in June, Greenland was losing ~12 billion tons of ice/snow per _day_.

Sure it was a bit higher insolation than now, but then whole thing was colder on average, i bet.

But most importantly, that june melt event was done by a high some ~1025 hPa strong (seeing it here). But this one we see developing, i see quite a few days being in 1030s, and i even see 1040+ couple times in the forecast! Wow. And yep it seems extremely stable system, too.

Snow thickness is projected to steadily decline next ~5 days from what i see, across whole Greenland, including every last grid cell in its central regions. Most of central Greenland i see its snow cover going from 48...72 cm to just 24...36 by August 1st, i.e. losing ~half of its snow cover despite all the elevation central Greenland has, - and the high seems not to be going anyware past that date, too. You don't lose those amounts of snow without massive melt event going, me thinks...

I suspect that much of ice retreat we now see directly north from Greenland is powered by melt water bottom melt, already. That water just gets significantly warm while running off the land, and then bottom-melts lots of ice once it's in the ocean. But after this event unfolding, with possibly over a hundred Gt meltwater runoff in a few days (i bet under-ice water bodies of Greenland are already overflowing by now), means up to few dozens Gt meltwater in a few days to the North side of it, and with such an insolation and already warmed up coasts? Can't even remotely evaluate the consequences, other than suspecting they might be devastating like nothing else before in the region.

Next week might well be no less historical than the GAC of 2012, gentlemen.

50
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 12:11:06 AM »
It takes a 80m high column of water at 4-5deg C to melt a single meter of ice. Melting of ice takes so much energy that it just takes a lot of time. The temperature of sea surface is some factor, but IMHO is not that important.
1st, this is factually wrong: 333.55 kJ to melt one kg of ice, -4.2 kJ to cool 1 kg of water by 1C. Cooling down 80 kg water by 4.5C would release 4.5 x 4.2 x 80 = 1512 kJ, i.e. ~5 times more than needed to melt 1 kg of ice. Means, it's not 80m high column per your example - but only ~16m.

2nd, both me and Oren already asked to stop doing napkin physics in this topic, recently. This topic is for melting season dynamics with only limited and small deviations. Normally you'd be asked to proceed with any more such posts in a more appopriate thread, like science base threads about ice melt physics, which this forum also has - but if you'd keep doing such mistakes, then with all respect and entirely friendly intent, i'd advice to not make them. See, you can mislead others with such posts. It's bad. But for sure it never hurts to ask and to post assumptions asking others to verify - in said ice physics threads. Please, do.

3rd, SSTs are not any much important any well inside ice-covered regions, as long as ice concentration is well above 50% (all the ice keeps SSTs near 0C); but at the edges of any ice cover and in areas with ~50% or lower concentration, especially with large subareas of open water (10+ km2) under clear sky and/or with wind blowing towards sea ice - SSTs become very important, in terms of melt season progress. Water currents also a factor, SSTs in stormy areas vs weak / thin ice cover is a dramatic thing, etc. I.e. SSTs importance is highly variable thing for a melt season and can't be estimated without taking other things into good consideration. Experienced posters often omit those details, only discussing SSTs when they are indeed affecting ice melt much, and simply not paying attention to SSTs when their consequences can't be anyhow foreseen in a definitive way. Which does not mean those guys don't make said consideration, you see. They do.

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