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Messages - F.Tnioli

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Arctic sea ice / Re: The 2020 melting season
« on: July 04, 2020, 06:06:08 PM »
This anticyclone is powerful, +1035 hPa, meaning warmed air and insolation on top of the CAB, but it won't mean much heat transported from the continents from now on ten days or so. If is was off center, for instance forming a system with a Greenland high it would bring the warmth from NA, but there is no much clockwise circulation over Greenland, so this predicted centered circulation kind of protects the Arctic from continental warmth. These first days however there is circulation bringing warmth from the Pacific along the Eurasia coast toward the Atlantic. But then it will subside.
Will be interesting to see what weights more from this weather outcome.
Torching at peak insolation is the worst, as we've seen countless times. No question about it.

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.

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:

Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 10:34:15 PM »
Thanks, F.Tnioli, for your answer. Consider me very skeptical on that one though. ;)
You're welcome, though i prefer to hear any sound argument behind your sceptical stance rather than mere statement you have one. Quid pro quo, they say. ;)

Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 07:56:59 PM »
But how about those ~5 GACs? Why do you think that? It strikes me as very unlikely.
Cyclones of the kind are born in temperate regions, strengthened there, and travel into Arctic to wreak havok and doom to sea ice (is my "french" too dramatic yet? :) ). So, one can look to temperate regions and estimate what is going on there to have an idea about what is likely regarding such cyclones. What i see is plenty places experiencing record _swings_ in temperature. Plenty strong winds, too. This points to likelyhood of more and stronger cyclones forming up, and some will probably head to the Arctic. This is the 1st over-simplified, generalized consideration pointing to the conclusion about multiple GACs likely.

The 2nd is what happens with peripheriral seas in the Arctic itself. It is well known that strongest storms have a tendency to rapidly weaken when they travel over lands (and by analogy, over ice, too) - while travelling over open water is often maintains their strength, at times even intensifying them. This general observation coupled with what we see happening to "low Arctic" seas right about now - like that 50k drop in ESS alone mentioned few posts above, etc, - plus cleaner air this season due to pandemic, and some other factors, - those point to the possibility that some time July / August we'll have plenty open water in "lower seas". Which can very much "feed" some moderate-strength cyclone going in and boost it to a GAC, or simply maintain strength of any "already GAC-scale" cyclone coming into the Arctic - for long enough for it to inflict GAC-scale damage to the ice.

Yet 3rd reason was also recently mentioned in this topic: overall general developments in the Arctic point to the likelyhood of GACs repeating themselves, but we did not see many since 2012 / 16. If any at all (opinions vary a bit). Thus, merely statistically, it's likely a year will come with not one, but few GACs striking in same season. Each passing year, statistically, considering said developments (ice state, temperatures' rise, GHGs rise, etc) - makes "multiple GACs a season" more likely. Personally, my opinion is that 2020, considering all circumstances, is indeed the 1st year when "more than one GAC a melting season" is becoming a big possibility. If it doesn't happen, i'd say we'd dodge not a "bullet", but rather something like a battleship's main caliber's shell. Something like this one:

Fuirther considerations / reasons would take much more space to describe and also would require me to bring serious analysis of certain publications, thus i apologize, but i am not going to do it. Hopefully above is sufficient.

P.S. Please consider the ullustration as a visualisation matherial intended to visually represent how dire things are in the Artic, Oren. That said, if you'd remove it, i'll respect your judgement, too.

Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 07:41:14 PM »
Naming will be discussed after the actual storm comes and goes. But I will not sign off on a "GAC" designation unless Neven himself signs off on it.
Of course! Neven it will have to be, i agree. Naturally, i did not mean to "name", above, merely proposed a variant for if the occasion would actually happen. Prematurely, yes; i have a weakness for proposing names to things, please forgive. %)

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.


- 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.

Arctic sea ice / Re: Arctic energy balance
« on: May 30, 2020, 10:28:35 PM »
This varies great deal seasonally. Polar night, it's surely low. But as soon as there is no ice, it gets big soon enough. Anyone in Alaska / Siberia will tell you: when it's polar day, thing can get pretty hot in the Arctic. Over 30C is nothing exceptional summer-time. Ice and to less extent open ocean prevent that, but Arctic as a whole still generates plenty hot air from its lands.

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.

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.

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.

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.

Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 03:15:04 PM »
Copy and paste from melting season thread.

Small difference in the calculation of weight of ice which is ~8% less dense than liquid water at 0.919 gram / cc. So 45.95 trillion kilograms.
This particular detail may need further correction for whenever one would be willing to calculate with precision: i read it's not 0.919, but 0.910 as reported on this page. In-situ density of 0.90...0.94 for below the waterline averages to 0.920, but seriously lower above-waterline density still drops overall ice density measurably below 0.919.

Thus i am generally using 0.91 - when not going "roughly" for round numbers of 1000 kg / m3, that is.

Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 02:52:01 PM »
More detailed about WAA.

Let's imagine a 1000 km width 1 km thick front. Wind speed is 5 m/s, temperature is 10°C, 100% humidity (10 g/m3 of water vapor). Density is 1.2 kg/m3, specific heat capacity is 1 kJ/(kg*°C), specific heat of vaporization is 2.3 MJ/kg. Total energy density is 1.2 kg/m3 * 1 kJ / (kg*°C) * 10°C + 2.3 MJ/kg * 10 g/m3 = 35 kJ/m3. Flux of air is 1 km * 1000 km * 5 m/s = 5*109 m3/s. Total power is 35 kJ/m3 * 5*109 m3/s = 1.75*1014 J/s = 1.5*1019 J/day.

This energy may be received by ice or dissipate into space. Both ways are probably significant.
And then you mean 1.5*10^19 J/day / 3.34^5 J/kg = 4.491^13 kg/day, which with density of sea ice ~910 kg/m3, we get 4.491*10^13 kg/day / 9.1*10^2 kg/m3 * 10^9 m3/km3 = 4.93*10^1 km3/day. I.e. 49.3 km3/day. Ok, got the math, close indeed to just call it 50.

But assumtptions? Man...

That amount of energy is not just being spent "either to space or to ice". It's not just half of IR "ends up" going up to space, which would already make it 25 km3/day; there are other huge "cuts" to the number, i think:

- only rather small fraction of that vapour will change to liquid through the _whole_ track of the front over the ice, because lots of it will remain as a gas. Never anything close to 0% humidity in summer Arctic, from what i see. So, good portion of that water vapour will remain largely unaffecting the ice if we talk 1km-high air column, so gotta cut resulting ice loss accordingly. Hell to estimate it - we can agree to "halve it again" for starters, so 12.5 km3/day?

- even "downwards" half of IR won't all be absorbed by the ice: good fraction will be reflected (even though in IR ice is less reflective than in optical - it still somewhat is), and good portion of that reflected IR will end up going up into space in addition to the half which was heading there to begin with. So, perhaps dropping it further from 12.5 km3/day to say 10 km3/day?

- for 1-km thick layer, "angled" downwards IR will suffer athmospheric opacity, especially longer wavelengths (this page has some good general info about). Thing is, the way i understand it, when an IR photon is being absorbed by air - sometimes it will result in another IR photon generated, but not always, because often times that IR photon's energy ends up being spent to increase kinetic energy of the atom which absorbed it (thus temperature increase). Thing is, with 1km-tall layer, density difference start to play a role: going "up" is noticeably easier for IR radiation than going "down", simply because there is "less per meter of altitude" air as you go up (lower density). When "re-iterated" great many times by IR exchanges, this difference becomes quite significant, and the whole process is really mind-boggling in complexity overall. For 1km-thick air layer - it'd take proper physicist, not me, to even napkin this; so again, can only offer to imagine the figure halved once again, so from 10 to 5 km3/day.

So, you see, those things combined, quite possibly would drop the resulting figure by an order of magnitude or so. 5 km3/day is still significant, but not seriously crazy anymore, right? :)

Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 12:40:14 PM »
Alright, now that we're not limited by main thread's requirements to omit excessive detail - i ask you to bring me the whole equation, sir. Mantissas of the numbers you gave don't quite fit the end result of "5.0" mantissa. Something's not clicking in. I'd like to figure out where i am not seeing what i need to see - or perhaps where you've slipped even if a little.

Because you know, like i said, 50 km^3 / day is quite crazy, yes? Thanks in advance!

Arctic sea ice / Re: The 2020 melting season
« on: May 29, 2020, 12:35:32 PM »
Ah, there we go, then it's "phew!" alright. I'm plenty sure we should not napkin-calc 1-km-tall layer for purposes of WAA to sea ice. IR transfer through this column will have massive losses: IR release is omni-directional, so lots of IR photons from mid and upper parts of that air mass will be released at all kinds of angles, half of them "upwards" at some angle; and then many of them which are going "somewhat downwards" - will be caught and re-radiated before reaching the ice. I believe well over half of total IR released by that air won't ever touch the ice, in the end, all known to me effects combined - if we talk 1 km tall air layer being the source of that IR radiation.

Further details and discussion, we all can dig into in that topic you created, yes.

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).

Arctic sea ice / Re: The 2020 melting season
« on: May 28, 2020, 01:35:13 PM »
Nice analogy.

WAA probably can affect the ice seriously. I got about 50 km3 of ice per day by calculations assuming high moisture. Though part of this energy will not be received by ice. And it reduces albedo sharply. Another thing is drought. May dry air mass cause a dust storm into the Arctic?
50 km^3 per day by WAA would be extremely serious, yes. If it'd happen... You sure you got the number right? Just stunned by that figure, tbh. And yet it still would be secondary, in the same time. How much km^3 can be gone by sunlight directly? Very roughly speaking, it's triple-digit figure, i.e. over 100 km^3 / day, as evident even from as simple info as "Perspective: Ice Loss and Energy" small chapter on this page and couple simplest napkin math lines, assuming (obviously) than most of ice melt during a melting season comes from direct insolation in less than 90 days (which is maximum insolation times in the Arctic).

Dust storms, were a concern in the past, already. One major effect is albedo drop of dust-covered ice. Personally i call it "dirty ice" (because it's quite that when you experience such ice personally), and i've seen such ice melt way, way faster than clean ice in real-world conditions, myself. Much of the dirt remains on top of it as it melts, continuously soaking lots of extra heat whenever exposed to the sun.

How likely / big dust storms can be? I don't really know, but at least we can see it's serious enough for Arctic dust storm monitoring network being talked about in 2016 (some details - here); glaciologists are acknowledging great effect dust can have on any ice (see for example this short piece); marine ecosystems can be affected strongly enough for piece like this one to exist.

However, from what i know, there is one major obstacle for dust storms to become a "key" factor for any large (means, thousands kilometers in diameter roughly) areas in the Arctic: usually, conditions which lead to extreme soil drying in the same time are resulting in lack of any strong winds in such (dried) areas. Largely, that is; exceptions regularly happen. But still. I.e., i don't think we'll have any significant (say over 10%) portion of Arctic sea ice ending up covered in so much dust that albedo drop caused by dust would dwarf other things which reduce albedo. I think dust storms will remain strong but regional factor, only.

Again, this is merely uneducated guess, though.

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.>

Arctic sea ice / Re: The 2020 melting season
« on: May 25, 2020, 12:14:08 AM »
I think this serves to bolster the notion that June of 2020 could truly be SCORCHING over parts of Eurasia, especially those which were warmest in the composite grab featured above. Simultaneously, the cooling this year has been worse in amplitude / scope (IMO) in NA vs. any year in the subset. I would think this portends a very MIXED and odd next thirty days in the Arctic, with accelerated melt in regions that do not normally melt fully until July (Kara, Barents, Laptev), and "protective" conditions in Hudson and the CAA. While Hudson will melt fully regardless, the conditions this spring could result in a very late or overall minimal melt-out in the CAA, and ensure it is relatively protected compared to the CAB this season.
I see some signs that Siberia would cool down serious deal few weeks onwards, though. Those seas will probably keep melting good deal nonetheless, but can be less than SCORCHING, so not holding my breath about it. As for CAA, obviously it was very lucky so far, yes, but we definitely should not exclude a possibility of some wild CAC wiping solid H2O out of the region some time August, for example. Especially if CAB/Siberian will pick up lots of heat by then.

Another very interesting thing of this development, which you indeed well described - is temperature contrasts. If CAA remains extra cold while say ESAS and around it will go all blue and sunny - then it can create some truly unprecedented winds. We've already seen some this March, but that's March. If similarly unprecedented winds happen say July - i imagine it can be one very new and very powerful factor in this season.

P.S. "CAC" being "Canadian-Arctic cyclone", that was. %)

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?

Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 10:07:35 PM »
The ice is very blue in the Hudson bay despite the land snow refuses to melt in that region during the entire spring.
May indicate significant heat content in the water right below that ice?

This reminds me. I am unable to get real-time ICESat-2 data (don't confuse with CryoSat-2 please!) myself. Do we have anybody able to give us the simple average snow thickness for Arctic sea ice for as close to "now" as possible? It'd be great to know what ICESat-2 instruments tell at this time.

We know that average maximum (= April) snow thickness on 1st-year ice is 16.8 cm, and average snow thickness on multi-year ice is 26.6 cm. Those are of course estimated and wildly vary in practice from season to season, but seeing what we have left now directly form instruments - can possibly be quite telling.

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.

Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 08:43:39 PM »
Indeed F. Tnioli, and very well explained, good post.

To your point Phoenix, yes it's true that early losses in peripheral seas such as Okhotsk, Hudson and Baffin are less meaningful than the same losses in the Inner Basin.
But this wasn't his point. This is your point - this one about "less meaningful than". What he said - was "almost meaningless". The two are much different IMO. I objected to his point, and i still think my objection holds true. But your point, in contrast, i entirely agree with. Less meaningful indeed; but still plenty meaningful overall. What you think?

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?

Arctic sea ice / Re: The 2020 melting season
« on: May 17, 2020, 11:34:34 AM »
Hardly any rain here (20 mm in 2 months, while average is 120 mm for 2 months) as well and lots of sunshine in March-April-May (basically since the lockdowns started). No proof of the lockdown-aerosol reduction effects, but I think there could be something to it. I have never seen so far, so clearly from our montaintop, I could see other mountains 2-300 kms away. Air was very clear and cloudless during the lockdowns. This is of course only anecdotal evidence but still...
Thanks for sharing it. From such small bits, bigger picture forms.

And it's not anecdotal. "Anecdotal" means: "evidence collected in a casual or informal manner and relying heavily or entirely on personal testimony". What you just said does not qualify to be "anecdotal", because it was not collected in "casual or informal manner" as relevant to the essense of your testimony. There is nothing "casual" nor "informal" about reporting specific range for visibility at a specific location, which you did; nor about specific amount of precipitation (20mm) as compared to usual average (120mm) for specific length of time (2 months).

Similar thing happens where i am at this time, too. I've never seen such a bright blue sky here during some 20+ years i am regularly present in the area. Now i see it almost every day, as even rainy days here - now often happen without complete (full) cloud cover during the day, instead being partially cloudy days (of which we had 20 out of 30 days of April here, which is above average for the month).

P.S. Plenty sun, too (now this is anecdotal alright) - bothers me personally as my main PC is right next to a SW window. Means i gotta bump up brightness / contrast of my display during those evening-sunshine hours, and then i gotta drop 'em down to low once sun sets. Problem is, sometimes i forget, and then it strains me eyes. Can i lawsuit 'em ones responsible for the whole pandemic / lockdown / clearer skies situation for extra bits of that eye damage i get as a result? Yeah. Figures. :D

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.

Arctic sea ice / Re: The 2020 melting season
« on: May 09, 2020, 05:03:41 AM »
Thank you for the better description of SMOS cutoff for Cryosat, and other SMOS limitations. This is what should have been posted in the first place if you find the original poster was not accurate enough. Clarify, explain, bring more info, make better wording. And do not hint the cutoff is to hide something or that somebody was lying because they used inaccurate terminology.

Back to what this topic is for - bringing information, data, analysis and commentary about the Arctic sea ice melting season that is just beginning in earnest.
When it seems someone is not accurate enough, i exactly offer a description which i deem better one. Like i just did above, - and there is no need to thank me for it really, such a small thing. "Not accurate enough" at some point gets "so off the target it doesn't look they are even trying" though.

I see it's time i walk outta that door - stay silent at least for fairly long while. Especially seeing you saying i anyhow stated that "someone's lying because they used inaccurate terminology". Which, i never did. Nothing even remotely close. I take this as a gentle hint that it's time i say good bye - what else can it be, seeing it's from you, not some stranger.

I'll keep reading now and then and of course, i wish you best of luck keeping things orderly and neat. Cheers!

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 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?

Arctic sea ice / Re: The 2020 melting season
« on: May 08, 2020, 09:42:54 PM »
Thus, CryoSat-2 thicknesses stop at April 30 and SMOS (respectively CryoSat-2/SMOS) thicknesses stop at April 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.

Arctic sea ice / Re: The 2020 melting season
« on: May 08, 2020, 04:54:31 PM »
here's the latest CryoSat-2/SMOS "measured" volume:

The graph stops in mid April, since melt ponds confuse the sensors
The figure's interesting to see alright, thanks for sharing! But here's one side note about it.

What melt ponds? Like was said above in the topic, there are no significant melt ponds in April in Arctic. Or were there? So, it sure looks like someone's lying: either those who said "no meltponds there", or whomever said "after mid-April melt ponds confused the sensors". Simple, right?

My guts say, it ain't melt ponds. DMI shows major volume drop in volume exactly in 2nd half of April. "Coincedence"? Hardly. And may i remind us all that DMI volume is "based on calculations using DMI's operational ocean and sea ice model HYCOM-CICE". Models don't get confused by melt ponds, eh. But people who see sensors showing volume going down when it shouldn't be going down even half as much - they have a reason to worry whether sensors are malfunctioning (or something gone wrong between sensors and actual collected data), and thus just make up an excuse and stop sharing data. Since they could be affraid at the time that collected data could be significantly wrong due to some technical malfunction or somesuch.

P.S. By the way, as of today DMI volume starts to dip down again. Already. Maybe CryoSat-2 now sees things which are way too wild to publish and the actual reason is not mainly about "melt ponds confuses sensors"? Confusions like this can sure happen aplenty when unexpected occurs. Please, let us try to find even more ways to estimate what's going on, gentlemen. It'd help.

Arctic sea ice / Re: The 2020 melting season
« on: May 06, 2020, 10:00:04 AM »
It looks like last week has been good for the ice. Volume has increased again.
Great news! I think, next week won't have unusually rapid total volume drop yet, too. But after ~15th, can be another unprecedented drop, it seems. Aluminium says about those 10...14 days, few posts above. And of course this whole deal about high pressure, too. I checked some air temps and winds couple days ago over ice in southern Greenland, a bit above surface, and it was up to 10C moist air going over rather big area there, which while not extremely abnormal then and there in the past - is still significantly higher than in previous seasons. Etc.

One usual feature of most kinds of collapsing systems - is increased volatility. This rapid drop last week is unusual, and now this rebound is also unusual. Thus, i think maybe we'll get another unusual drop by the end of May, possibly ending the month below 20k km3 in DMI numbers. I wonder how much, exactly, this "collapsing system is more volatile than usual" could apply to sea ice / melting season, though.

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.

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.

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.

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.

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, 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.

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.

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.

Arctic sea ice / Re: The 2020 melting season
« on: April 28, 2020, 01:33:01 PM »
Would it be more informative if I changed how many years the current year is compared to. Maybe post-2012 instead?
Yes, it would be. 2013 and onwards is a whole new league of its own.

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!

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:,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.

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.

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...

Arctic sea ice / Re: The 2020 melting season
« on: April 27, 2020, 11:52:24 AM »
Some opportunities are better not attempted too early, though. Unintended consequences of premature experimentation can be quite upsetting. :·)

<Please avoid posting OT YouTube videos in the main thread, though I appreciate the humor. O>

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...

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.

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: ). 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: .

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.

Arctic sea ice / Re: The 2019/2020 freezing season
« on: March 02, 2020, 12:16:26 PM »
I think to put it in context Hefaistos, you need to think not necessarily about what's happening now, but where conditions will be in 3-4 weeks.

What is happening is setup, much like how much running room you have leading up to a broad jump.  By losing snow this early, and picking up what are modest but still significant amounts of solar energy means that considerably more energy will
(1) ... be captured directly at Arctic latitudes
(2) ... be available early in the melt season
(3) ... not be required for/buffered by local phase change (e.g. melting snow locally)
(4) ... indirectly permit more transport of heat to the Arctic from lower latitudes. (primarily via
          increased moisture)

That's why lots of bare ground at high latitudes is concerning, even before the equinox.
Right. I can also add (5) to the list: less snow cover "buffer" to resist melting season start.

By this, i mean that when some place say south of Finland has 0 cm snow cover or say 10 cm snow cover - while the average for the place is say 1 meter of snow cover, by March 1st, - then very little to zero heat is needed to have the place's surface to start absorbing sunlight as soon as the Sun starts to put any substantial amount of it in. When such a place is say few millions km2, this will warm up cyclone-scaled air masses in a matter of couple weeks or so; while normally, they'd remain on top of (slowly melting, but still largely white) snow-covered land. Means most outcoming radiation is simply reflected, i.e. short-wave; while in this "new normal", lots of outcoming radiation is long-wave (infra-red), thus greenhouse gases further add in even more heat to the air.

There certainly are some situations in Arctic and next to it when further increase of temperatures is slowed / halted by some strong negative feedbacks, but "little / no snow late winter and early spring" is one opposite case; positive feedbacks seem to strongly prevail.

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...

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