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Messages - seaicesailor

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1
Arctic sea ice / Re: The 2017 melting season
« on: April 27, 2017, 12:25:25 AM »
For the next five days, high pressure system coming back to the pacific side of Arctic, but ACNFS predicts very modest intensity of induced clockwise drift.
Pressure gradients not as intense as in the first half of April? We'll see how it goes.

2
Arctic sea ice / Re: IJIS
« on: April 26, 2017, 12:08:47 AM »
Seaicesailor - Graphics down on the home page of Tealight's site.  From his site, I pulled the following graph (albedo derived from NSIDC concentration data) Is this the most relevant graph?
Yes. The cumulative FDD graph is the most relevant for winter, and the one you posted is the most relevant over the melting season
I think so too. Worth keeping an eye during the season!

3
Arctic sea ice / Re: IJIS
« on: April 25, 2017, 08:33:43 PM »
Last year the Beaufort sea gap kept opening steadily until well entered may 2016, which contributed in part to anomalously low extent. The north of Svalbard was clear-cut clean by mid may while this year is covered by MYI that will be clearing gradually. The timing is different this year too, would be surprised if the curve follows 2016.
To add that Greenland Sea and Barentz have seen import of much thicker ice this year... "good" for extent now, bad for the prospects of ice
Surprisingly even with higher extent Tealight's accumulated albedo potential anomaly is running highest, although very small numbers, still very early in the season
https://sites.google.com/site/cryospherecomputing/warming-potential/graphs

4
Arctic sea ice / Re: The 2017 melting season
« on: April 25, 2017, 12:05:11 AM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.




How Strange. I guess everyone's eyes are different, and its often easy to see what you want to see. But when I look at these comparisons I see significantly more cracks than 2016. And of course the results of a strong four day compaction event that's just occurred. I hope it doesn't mean I want to see everything crack up. ::)

Yes but the area of open water was completely crazy. This year it looks more normal and its been really cold.
"Give it time", well indeed according to the forecasts a high over Beaufort is back on day 4 from today and somehow warmer temps too. First weeks of May we see what happens with the cracks. They look really solid now!

5
Arctic sea ice / Re: The 2017 melting season
« on: April 24, 2017, 08:32:44 AM »
I can see a floe which is at 175E 70.15N on the 20th and moves about 70km to the next image on the 21st. We don't know for sure when these images were taken because the tiling can be irregular so maybe not exactly 24h. Nullschool gives wind speed of 27km/h as a max for early on the 20th, falling to 16km/h later.
I don't claim to know much about velocity of ocean currents but expect them to be lower, the example in bering strait given earlier was in hundreds of meters an hour. The way velocity picks up from one day to the next and directions change in these ice movements make me more inclined to think of them driven by wind. Do ocean currents change that quickly?
We saw similar fast movement of floes in Beaufort last year near the edge of the pack, my hunch then was that local eddies are spun by currents which move in different directions in deeper and shallower water. Maybe ice driven by wind produces local current at the surface?
I don't know the 1/30th rule, can you explain?
Makes sense (that around that cape there may be some local effect, some eddie acting on the floe). You are right about the current, 600 m/h is not negligible anyway, but much slower indeed.
The 1/30th rule of thumb is something I came up with last year to estimate the proportion between sustained winds speeds and generated drift speed. It is not accurate by all means depending in many factors (in fact, for instance, in that paper by Zhang and others about the GAC the ratio implied for the drifting marginal  ice in CAB under the storm was more like 1/20th iirc). It's just an order of magnitude that works ok. In steady state the pull due to wind and drag due to water are of same order (not the same since there is Coriolis) and further assuming similar surface and bottom drag coefficients the ratio of speeds goes with the square root of density air/water. As I said, really crude but it gets close when the floes are already loose.
Sorry for the lengthy explanation.

6
Arctic sea ice / Re: The 2017 melting season
« on: April 23, 2017, 08:24:59 PM »

Its quite stunning how fast the current is surging along there.

Thanks Hyperion. This must be current, because wind direction has been towards Pacific. I compared Apr 22 this year vs 2016. Not the best situation and we know that temps are mild over next 7 days there. Also looked long-term forecast (CFS), first week of May still large positive anomalies over Chukchi Sea and ESS coast. Images: Worldview.
Archimid has shown wind blowing in the direction of ice movement, so no, repeated assertions "this must be current" are not enough to convince me that this is what's happening. We know ice is thinner there this year, which makes movement easier and air temperatures are not cold enough to freeze water opened by ice movement, that is the most plausible explanation unless someone has other information.
Alright... but in that animation there are some floes moving like impelled by strong currents near the fast ice, does seem a bit too fast to be just the wind.
And why so much difference with Laptev sea...
Anyway, it really calls the attention
Edit. Attached a cropped version of Hyperion's gif showing only the area of the channel between Wrangel island and the ESS fast ice. A lot of momentum there
There's a floe there that flies more than 100 km in a single day (or more, almost like length of Wrangel which is more like 150 km). The 1/30 rule of thumb says a wind of 120 km/h would be needed to generate such drift... am I missing something?

7
Arctic sea ice / Re: The 2017 melting season
« on: April 23, 2017, 01:14:19 PM »
Lets try a homemade one rather than a NASA nasty.
Its quite stunning how fast the current is surging along there. I know that often warmer salty water slides in on the bottom through the Bering straight, while it can even be flowing out on the surface. Certainly if its Pacific water making it all the way along there, the offshore wind would blow the fresher lens away and help it surface.

Still not playing. is there a size limit?
I guess yes.  ::)
Nice animation. Yes I agree on the surge of Pacific water. ACNFS has been showing a stream toward the bering Strait since March, so probably this has been running under the ice for longer than a week, but since Hycom ACNFS animations are not really clear on that, this is just a suspicion that the first pulse of Pacific water has come really early this year. Which is aggravated by a anomalously warmer atmospheric situation and a really crappy ice to start with! Thin and broken.

The CFS long-range prediction as wonderfully represented in Levi Cowan's site (tropicaltidbits.com) shows a Siberia anomalously warm for the month of May. Last month it predicted the emergence of Beaufort high pressure many days in advance when the Arctic was completely dominated by lows, it was surprising how well it predicted it. Keeping an eye on these forecasts, we'll see if they serve during summer.

I believe the CFS-v2 model has been recently changed (impacting for instance El Niño predictions), but others here may know more about that.

8
Arctic sea ice / Re: The 2017 melting season
« on: April 23, 2017, 12:07:50 AM »
Interesting that this polynya that appeared about 1 week ago in ESS is about the only one within the Arctic proper not showing signs of refreeze. Why there?
Being April 22 big chances it will stay open.

9
I give you one number, you're the number one that I have put in ignore in this forum.

10
Arctic sea ice / Re: The 2017 melting season
« on: April 22, 2017, 02:39:57 PM »
A close-up of the evolution of SST anomalies in Bering sea during past 30 days or so (from the DMI SST anomalies maps). Insolation and ocean currents make a difference there already.

11
...
The Beaufort sea cracks and sea ice in general may be refreezing at a good pace compared to last year even with no MYI. Cold temperatures and lack of movement again and perhaps thin ice negative feedback since January.
If some Beaufort sea ice survives this year, there may not be any record soon. It all, still, hangs on this summers weather.
(emphasis mine)
That's a lot of conditionals right there, seaicesailor. Back to the numbers/science, what is the trend? What is the statistical uncertainty associated with the data we have? What does it tell us?
What can I tell you. I am not a god like you. I don't have the certainty that you have you that see past and future with pristine clarity. For a god like you we us the group are denialists/lukewarmists/trolls (or just denialists).

12
When people talk like that it sounds like the Inquisition that saw heresy just in everything.


No, it doesn't.  That's just your cognitive dissonance talking.  If anyone is shouting, "Heresy!", it's you.  Nor does 1 year or 5 make that much difference.  We are like swirling around the toilet bowl just before it all goes down the drain.  Inevitable.
So you are talking to my cognitive dissonance now.
All right then. Then I better leave you with it.

13
No, it doesn't.  Nor does 1 year or 5 make that much difference.  We are like swirling around the toilet bowl just before it all goes down the drain.  Inevitable.
I answered to exact same comment in 2013 in Nevens blog and I won't answer again to avoid the ridiculous interchange that ensued.
Weather matters a lot (at least for September extent). And september extent matters a lot for the following winter.
However it has been more than established that there is very poor correlation between winter maximum and following summer minimum. By the way.

14
Jai,
This is definitely a revealing poll about what the people here a ASIF think about the demise of Arctic sea ice.
Now, I can see exactly why practically half the people who voted, voted 2020-2030 (because I voted in that category).
I can also see why some people voted > 2090: denialists or essentially the same thing, trolls.
Finally, I can also see why some people voted 2030-2040: "lukewarmists", which is a special form of denialism, where you recognize the reality but just wish you can retire before "the shit hits the fan" the worst effects of AGW show themselves clearly.

What I really don't get is why some people voted 2040-2050 (12 people as of now), 2050-2060 (5) or 2060-2070 (6).

What is the tortuous reasoning that leads some people to postpone (in their minds) the conclusion of the disaster that is happening right under their eyes? Is it just younger "lukewarmists"? Or denialists just using some sophistry to obfuscate the science?

Perhaps some of them could come forward and explain their "point of view"? Or anybody here wants to play "devil's advocate" (for each of these three categories)?

When people talk like that it sounds like the Inquisition that saw heresy just in everything. Especially in scientists. Where did the Galileo in you go?
The Beaufort sea cracks and sea ice in general may be refreezing at a good pace compared to last year even with no MYI. Cold temperatures and lack of movement again and pehaps thin ice negative feedback since January.
If some Beaufort sea ice survives this year, there may not be any record soon. It all, still, hangs on this summers weather.

15
Arctic sea ice / Re: Stupid Questions :o
« on: April 21, 2017, 07:44:11 PM »
Then Scientist American article explaining and debunking a lot of crap you find out there
https://www.scientificamerican.com/article/why-carbon-dioxide-is-greenhouse-gas/
And i like this simplistic kind of explanations:
https://scied.ucar.edu/carbon-dioxide-absorbs-and-re-emits-infrared-radiation
But if you dont believe it , you have tons of lab (and very accurate quantum dynamics models lately) results, and if you don't believe it, .... well you are free in your beliefs :-)

17
Removed my last comment, was off-topic.
Sterks, it is a serious and difficult problem indeed. This year might be interesting to see how the floor topography affects the final shape of the pack.
:-)

18

The transition from a desert to a maritime climate happened in late December 2015.

Based on what? On some plumes of humidity over the Arctic? You don't know if that is an annual variation, or decadal, or what. You know as much as I do or any around (except maybe the owner of the site, Rob, Dr. Ding and a handful more), which is nothing.

Based on a graph???? Lol. Based on clairvoyance, a vision in dreams or what?

In September 2012 "a tipping point was crossed", in November Sandy . But Did we? Or didn't we? Cause 2013 and 2014 were pretty unispiring seasons for some that shut their mouth for a good and nice while.
Same we heard when Katrina in 2005 "We will never come back to past seasons". Well, in what respects to Atlantic hurricanes, we are back to old times.

2017? Does not look good, if you ask me even worse than 2016, but how I wish it was otherwise.

19
Arctic sea ice / Re: The 2017 melting season
« on: April 20, 2017, 12:14:06 AM »
Granted this is valid for 5 days most, but I wonder if this is the recurrent configuration Ding was referring to: highs persistent over Greenland Canada and Arctic with lows pulling warmth from the continents (in summer). Just a comment, not sure it is even close :-)

20
Arctic sea ice / Re: The 2017 melting season
« on: April 19, 2017, 11:55:41 PM »
I am liking these weekly CFS forecast visualisations of Tropicaltidbits. Somehow the CFS forecast retains a lot that the ECMWF and GFS forecast for the coming seven days and it is nice to observe some consistency and agreement in a single averaged-values map.
One thing is that a sustained strong winds favoring Fram export.
The second is that, while no above zero temps are forecasted over the Arctic, they indeed will be reached in many locations of Siberia (at brief moments), in agreement with the CFS predicted southerlies and warmer than average temps.
Beaufort sea Anticiclonic and cold for a while. Should be quite sunny though, stable situation all pacific side.

Getting closer to the real melting season so to speak.

22
Arctic sea ice / Re: The 2017 melting season
« on: April 19, 2017, 07:44:37 AM »
Tigertown, I never saw any evidence the Beaufort Gyre had stopped. From the post I made on Mar. 31 ITP 98 has moved from 55.99 to it's current location at 55.56 The buoy track line never showed anything but clockwise drift and neither did the other two ITP buoys reporting locations in the Beaufort.


19
Arctic sea ice / Re: The 2017 melting season
« on: March 31, 2017, 07:39:58 AM »
Tigertown, There are still four ITP WHOI buoys reporting locations. Three in the Beaufort gyre 97, 98, 99 and  93 trapped into fast ice on the north coast of Svalbard.  The thing I find intriguing  is that none of the reporting buoys in the Beaufort gyre show the Northwest thick ice drift modeled in your last post. I have to believe buoys sending real time data over models in this case.
 I like to watch the temp /salinity contours but sadly we only have one of the above listed buoys still sending T/S profiles this year.

http://www.whoi.edu/page.do?pid=155136

This buoy is sitting just North of McClure Strait and should show northward drift if the model was representing current conditions

http://www.whoi.edu/page.do?pid=155156
ReplyQuoteNotify

Bruce, candid question: shouldn't we distinguish between ice drift, and the ocean current in the case of the Gyre?. The first has not shown a net clockwise pattern from December to March  (or at least really visible; maybe averaged over many days it is possible), the second, I cannot say but I assume it is there, still in with net clockwise sense, perhaps in a weakened phase... should take many years to stop or reverse the Gyre (ocean current)

23
The forum / Re: Closed forum or mailing list
« on: April 18, 2017, 09:57:29 PM »
I don't know if it's possible to set up a mailing list or a separate forum for invitees only, but I'm also not sure whether it would be worth the trouble. The 'abuse' was hurled by just a few people, and most of I wouldn't even call abuse. Ever since Qinghua Ding engaged here, the 'abuse' has become even less. On the other hand he does say (based on his research) that the Arctic won't go ice-free for another 50-100 years, so some push-back is to be expected on a forum for people who are worried about AGW.
I think Dr. Ding made a mistake saying that to the media, looks like a conjecture of his rather than directly from the discussed papers. Obviously bringing that to here cannot but lead to a circus.
That thread was really nice, I learned a few things of climate science, an expert entered the discussion, and... it finally motivated me to look for the ignore list and add a few names for the first time (not even Vid could get that from me!).
So great idea to move it to private and keep it civil.

24
Arctic sea ice / Re: The 2017 melting season
« on: April 18, 2017, 05:52:51 PM »
last year (Feb / Mar 2016) there was a lot of movement of ice westward compacting and thickening against the siberian coast east of Wrangel island. The lack of this movement  makes the thickness there so much different (i.e. thinner this year) as seen in PIOMAS and in cryosat. This should show itself in the melt season which last year had a marked stall in June (red line is 2016)
https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png
I tracked some of that compaction last year:
..... I have looked at deformation of ice in the western Chukchi sea where PIOMAS and cryosat are showing surprisingly thick ice.
The images are AMSR-2 brightness temperature on worldview http://go.nasa.gov/1XXcE1b
Although I don't think I can relate the colours shown to thickness or other clearly identifiable parameters of the ice, they do show up persistent features which help tracking movement over long periods and through clouds. Unfortunately there are no AMSR-2 images in worldview before 12 Jan 2016.
I have marked some features which show a reduction in area between these features and therefore an increase in thickness, because at that time of the year volume does not decrease.
I expect that to happen through formation of ridges so that the average thickness includes first year ice with thickness below 2m together with overriding and tilted floe edges which form  the much thicker ridges.
dates are shown in file names: 4 Feb, 20 Feb, 5 Mar, 21 Mar


Definitely last year there was an stagnation of ice around the Chukchi/ESS sector of the CAB and the ESS that is not present this year. Perhaps the fact that during april there has been such a massive drift toward Atlantic/Fram while last year the flow was a bit different.
The ECMWF hints of yet three of four days of vigorous transpolar drift. The CFS weekly prediction nicely represented by TropicalTidbits kind of agrees with the nice "textbook" pattern of the coming days, less vigorous in the pacific side but massive still thanks to a low over Scandinavia coupling with the overall Arctic high pressure

25
Arctic sea ice / Re: The 2017 melting season
« on: April 18, 2017, 02:21:10 PM »
Chukchi Sea April 13-16, about 78 hours
   A striking view of a rare occurrence.

Very difficult to vector that sort of mobility into any prediction for September.
   Same for me.  I suppose the open areas will refreeze as the season is still quite early in Chukchi, but it seems likely the structural and thermal damage will be more lasting.

Also, I suspect there has been flow of Pacific water from south along the asian side (of the Pacific) into the Bering sea since Feb/March, which has been stagnating in the Bering sea, since the clearing of Bering sea ice up to the Bering strait has proceeded as a tongue entering from that side. Hycom indeed seemed to suggest such flow. Now this water could pour into the Arctic, representing the first significant pulse of water into the Arctic pretty early in the season.
See JAXA ice melt animation starting Mar 1

26

Personally, I think anyone that voted anything other than 2020-2030 in the poll above is a denialist, consciously or not.


Wow Thank you!
And
What the hell do you know?

27
This one calls for very wild speculation.
Since ASI (Artificial Super Intelligence) is predicted to emerge around 2050-2060, and I optimistically believe that there will be some ocassional summers with enough ASI (Arctic sea ice) left until then, my guess is this entity will fix the AGW problem in a couple of years while deciding what to do with us terrified humans, whether remove us from existence or preserve us with some genetic modding so as to not destroy own own planet while the entity self replicates and populates the galaxy after discovering interstellar travel in a picosecond of relax.
https://medium.com/ai-revolution/when-will-the-first-machine-become-superintelligent-ae5a6f128503
http://waitbutwhy.com/2015/01/artificial-intelligence-revolution-1.html

So I go with >2090

28
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 14, 2017, 01:57:21 PM »
and confirms the exponential trend.
How many fails are needed before you decide gompertz is better trend than exponential?
...

The choice of Gompertz over exponential depends on whether you believe negative feedbacks overwhelm positive feedbacks as we approach a sea ice free state in the Arctic.
I happen to believe that there are much stronger positive feedbacks than negative feedbacks that affect Arctic sea ice volume, so the exponential trend makes more sense to me.
Mathematically in terms of "best fit" both trends are more or less equivalent. And at this stage both trends show the Arctic going essentially sea ice free within a few years difference.

So suit yourself and choose whatever trendline you like best. As I wrote in another thread, the words you choose to describe the unfolding Arctic sea ice (and global climate) catastrophe(s) changes not one bit of the reality.

Funny that use a model that suits your preconceived conclusion (zero volume), given one of the arguments you use to discredit that paper over the other thread (to use a model that suits a preconceived conclusion).
But well we are not scientists. Are we?

29
Arctic sea ice / Re: The 2017 melting season
« on: April 13, 2017, 02:28:23 PM »
And starting with the ACNFS Hycom drift prediction from the 13th to 17th. The clockwise drift starting to look like a textbook Arctic drift map, something not seen much in all past winter.
Ice might detach even further from Amundsen bay Gulf as well

Gosh those vectors are long!  The ice movement seems to be virtually unrestrained by any cohesion in the pack.  Any sustained blow from north towards the CAA, Nares or Barents will just shove already-chewed up ice into the oven.
Adam,
I should add the link to ACNFS page so that anybody can see the legend of color and the corresponding speed for a given arrow size, I am careless and just crop out without including them
https://www7320.nrlssc.navy.mil/hycomARC/arctic.html

But to give an idea the darkest red is 30 cm/s, 25 km/day approx, so if a region has sustained drift of that intensity for four days, I know gaps of order of 100 km wide are to appear (or existing ones widening up by as much) near the coasts of Alaska. Perhaps 40 km, perhaps 120 km, but not 10 km, not 200 km. I would not look at the arrows strict sense as if they indicate real displacement, but I just make that sort of mental rough calculation.
so, the Beaufort sea is gonna be in deep in May.

30
Arctic sea ice / Re: The 2017 melting season
« on: April 13, 2017, 01:33:49 AM »
And starting with the ACNFS Hycom drift prediction from the 13th to 17th. The clockwise drift starting to look like a textbook Arctic drift map, something not seen much in all past winter.
Ice might detach even further from Amundsen bay Gulf as well

31
Arctic sea ice / Re: The 2017 melting season
« on: April 13, 2017, 01:21:34 AM »
Given the forecast, we can expect more of that. I'll try and make an updated animation.

Edit: I still had the template from last year:
2017 Beaufort looks to be trying mightily to catch up with 2016's open water.  It becomes more clear looking at it in Worldview, where you can see in particular just how shattered the ice is.  There may be more coverage than last year, but it is not robust. The Amundsen Gulf in particular has disintegrated into a bowl of ice cubes.
Yes and given that the high is going to strengthen and stay around 1050 hpa for three days, we'll definitively have material for animations.
Image from Tropicaltidbits ECMWF last run, forecast +72h

32
Arctic sea ice / Re: Stupid Questions :o
« on: April 12, 2017, 06:48:38 PM »
Of course we see open water (the darkest of the "rings" being formed around the separating floes) but it is proportionally very small area wrt grey bands of refrozen ice. Actually your animation TT spans like seven days and maybe only 1/50th of the area is open water. That means to me that water stays open in average three hours (or lets say a few hours) before closing

33
Arctic sea ice / Re: The 2017 melting season
« on: April 12, 2017, 11:40:41 AM »
I wanted to relate that the worldview "Sea Ice Brightness Temperature" overlays make it all very real, to me at least, since they cut through the darkness and clouds to make it easy to see actual day-to-day ice migration across the arctic.

For what it's worth I used the above to make an amateurish video comparison of this year vs last for the Greenland/Atlantic quadrant for Mar 01 - Apr 11. It's at:

https://youtu.be/Yf73zutgeDU

...Don't know if it will have the same impact on others as it did on me, but IMO the main takeaway is that if we thought that the ice was a) too warm and b) unprecedentedly mobile and c) headed in the wrong direction in 2016, then hold on to your hats - because so far, at least, 2017 looks much worse.
Nice video, clearly reflects Fram export amount has been on the high side and a lot of ice is now being stationed in danger zone (anywhere around Svalbard, and  Greenland sea)
What the video cannot reflect is that the proportion of outgoing ice being more than 2 years old is higher this year than the past. Perhaps why it is surviving stationed near Svalbard for long time while last year it just vanished miles north of the islands. Sadly, because the overall MYI amount is supposed to be much smaller than last year's.

34
Actually, why don-'t we LEAVE SCIENTISTS ALONE now that they are being actively prosecuted, buried, insulted by Trump????????????????????????????????????????

35
6.  We need to stop allowing our scientific body to...
Didn't the last POTUS tweet start along similar phrasing?
Why don't we let the scientists alone do their fine good job?

36
Arctic sea ice / Re: Stupid Questions :o
« on: April 08, 2017, 09:48:40 PM »
Whether it freezes or not, that image shows dramatically how fragile 1.5 meter thick ice is.
Right, already hundreds (or thousands) of floes of all range of sizes and the melting season yet not even started there.

37
Arctic sea ice / Re: Stupid Questions :o
« on: April 08, 2017, 11:43:05 AM »
P.S. I see on http://www.arctic.io/explorer/4Xa5A//4-N90-E0 that ice is still forming on Jakobshavn fjord (07/04/17) so radiation balance is not enough?! Open water is freezing all over the Arctic Ocean, the only melt seems to be at the southern fringes (Baffin Bay, Fram Strait, Bering Sea, Barents Sea). Cold still coming off the ice?

Nice viewer ...
See the widening opening in Beaufort sea. Alaska is still freaking cold. It might be that sun radiation is about to overcome olr but southerlies or easterlies there are really cold today. The opening will refreeze before May

38
Arctic sea ice / Re: Stupid Questions :o
« on: April 08, 2017, 11:20:46 AM »
So a relatively simple question motivated by seeing some new ice form...

Do we know what day is breakeven for heat flux, counting only radiation, at various latitudes? Assume clear skies (though I'd be curious for cloudy too), and open water at 0C for albedo/blackbody purposes.

That is - if we only look at heat gained from the sun and heat lost via longwave to space (ignore atmospheric interaction, upwelling, currents, etc), what day of the solar year does this breakeven occur at various latitudes?

The original question seems to be asking when is the sunshine strong enough to balance OLR on open water (leads, etc.) without drawing energy from other sources. From the graphs it this thread I would put OLR at about 220w/m2 from cold water (but someone will have an accurate figure?), agreeing with late March to mid April. It would only be theoretical because in practice this would be later than ice would form (as the seawater would need to cool to about -10°C for ice to form) unless a lot of 'cold' was imported from somewhere else.
OTOH because of the high albedo of ice/snow there still would not be enough energy absorbed to actually melt anything and the surface is likely to remain below 00C  until the sunshine is considerably stronger (but OLR would also be lower and more variable). That makes for another interesting question?
That "-10C for ice to form" is just a rule of thumb, or a simplified way to say that there are other heat sources, as for example water warmed up during summer in the upper layer of the ocean, that keep ocean water surface above freezing point for some time even when atm temps plunge well over zero, and as long as there is some stirring and mixing.
That is all for the freezing season start. As for the melting season start, something similar happens, there are additional effects that (most probably) delay the persistence of open water.
An important factor is the effect of  land masses. In fall, air advected from continents starts to have a cooling effect, whereas at some point of the Spring, air acvected from continents starts to have a warming effect. I believe the effect of transported heat this way is not totally accounted for in the OLR - incoming sw radiation balance approximation. That makes the problem very location-dependent. It also adds some inertia to the problem, (I think), since you need to have land snow cover meltout ongoing (or gone) in order to not receive spells of cold air advected from the continents, delaying the day of overall heat balance for some days.
By observing a few seasons as I said for me the 1st of May is when the bell rings for this particular problem, plus minus 10 days

39
Arctic sea ice / Re: The 2017 melting season
« on: April 08, 2017, 12:07:42 AM »
... I'll be posting the first poll in June, and I would kindly ask others not to open polls before that.

It's a crap shoot either way, but projections are more solid after the first phase of the melting season has passed (April-May-first week of June).
Yep, that's just the way the Sea Ice Prediction Network team see it as well.


But I wonder if at some point the correlation can go further into May, April,... like for example when there is not enough ice past the Winter.

Extreme unreal  case to make myself understand, if there be zero ice in March, there be zero ice in September.

Being more realistic, if volume available in April keeps decreasing until a moment the heat brought by a less than average warm season is enough to melt it all, the SIPN wont make sense anymore, or our polls :-( (the least of the problems in reality).

40
Arctic sea ice / Re: The 2017 melting season
« on: April 07, 2017, 11:46:40 AM »
Both GFS and ECMWF deterministic runs indicating lots of high pressure. Here are 120 and 240 hours from each. Too early for the sun to do much preconditioning?


Not yet I believe (see ongoing stupid questions discussions), but the last ecwmf run sees the current Beaufort high become strong and persistent. Overall Beaufort sea albedo to continue downwards (because of cracks and openings)

Second half of the animation not to be taken really seriously (that warm wave with 1050 hPa???).

41
Arctic sea ice / Re: Stupid Questions :o
« on: April 06, 2017, 08:20:25 PM »

Yep, water is no blackbody. Nor is ice. The atmosphere makes this a tricky question.


Make simplyfying assumptions as necessary. I was trying to throw weather out, where possible.  Pick your favorite weather, average the weather, whatever makes the calculation easy.

I'm looking for a ballpark figure; when the sun is enough on its own to keep the water open. I really don't have a sense of it.

You can always cheat and use observations; we have pretty good observations of temperature of outbound (as measured by satellite), a pretty good sense of albedo (I did suggest open water), and a little internet digging will give you the incident (I know they exist, though I was't having much luck finding a good one).  It's true that observations are prone to all sorts of variables (most notably clouds) but it should be a decent ballpark.

By early May, the insolation for north pole crosses the incident of the equator so certainly it's somewhere sooner than that. At equinox it's 0W incident, so it's later than that. It gives about a 50 day range; I'd say probably it's between April 1 and May 10 just based on that information.
I'd say April 20 and May 10 for peripheral seas (within the Arctic proper) based on what we observed other years, that is, when new cracks do not refreeze anymore.
We have seen refreezing in the middle of the CAB happen much later, even after generalized surface melting. I guess when a crack is surrounded 360 by ice and a cold spell comes, the refreezing is easier...
Really tricky stuff

42
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 06, 2017, 08:05:06 PM »
Greenland sheet contains about 3 million km3 of ice. That might be enough for keeping some chill around, and those ~1000 km3 of "virtually ice-free" Arctic thru summer

43
Arctic sea ice / Re: The 2017 melting season
« on: April 06, 2017, 12:55:37 PM »
I think the below is a bit deceptive, as last year I think we saw much more of this north of alaska. But doesn't diminish the general concept that everyone has been noting - the ice pack appears much more susceptible to winds and transport.

April 1-5

Alaska in bottom center

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1



I think it is really bad, my honest opinion. The second comparison above by Jay shows that we can end up with a pretty extensive web of cracks and (worse) coastal openings, and while this does not have the size of 2016 event at all, it already establishes sinks of solar radiation heat from May on. It seemed this year Beaufort sea might have spared this (or delayed it enough) but no. And let us remember, no MYI here whatsoever.

44
Arctic sea ice / Re: The 2017 melting season
« on: April 06, 2017, 12:02:50 AM »
April 1-5

Alaska in bottom center

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1

So the chances of Beaufort sea ice to survive rapidly diminish, as early as April, I believe these cracks will seed the albedo feedback come May just as past two seasons. The drift is going to continue for at least one week.
Not good. Thinnest ice overall ever (recorded), but the details are not better, eurasian side looks already like crap from Kara sea to ESS, and the MYI cannot be more compromised toward the Atlantic.

45
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 05, 2017, 09:56:44 AM »
Chris Reynolds no longer updates on the regional GICE thickness distributions of PIOMAS but it would be of great interest right now. I might give it a try if I find the time, but no expert on post-processing gridded stuff. If anybody has the guts (and the time...) :-)

46
Arctic sea ice / Re: The 2017 melting season
« on: April 05, 2017, 09:40:02 AM »
Latest GFS anomalies until next Wednesday and 5-day outlook (Climate Reanalyzer). Seems like next week anomalies north of °65 are lowest seen for quite a long time as long-term mean temperatures now start to rise.
Thanks Romett for putting together this info every day, really nice to see it

47
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: April 04, 2017, 11:40:26 PM »
Really troubling. The energy required for a meltout is at reach of the two or three worst summers in the last ten years, not just 2012. A 2007-like might end it too, the '15 and '16 summers also saw a strong volume decline.
But small details count, early cracks, warm spells, ocean currents... sun or storms? Can amplify the heat or mitigate the feedbacks.
Another gloomy start of the melting season.

48
Arctic sea ice / Re: The 2017 melting season
« on: April 04, 2017, 11:39:55 AM »
Last but not least, some detail using Aqua Modis bands 7-2-1 that shows just exactly what happens when that ice reaches the "scorching" Atlantic heat influx we've been watching for the last 2 years.
I am not sure this ice can last for the summer...

49
What I don't understand in all this discussion is why that presumed natural variability that shows as a GPH ridge over Greenland and all associated perturbed circulation so detrimental for the ice cannot have been caused, indirectly, by the so many changes AGW has directly caused, in the SSTs, the humidity, the glaciers, the sea ice and so on. Just what comes first to the head of a layman...

50
Arctic sea ice / Re: The 2017 melting season
« on: April 02, 2017, 03:16:15 PM »
The Beaufort sea ice cracks that appeared in March 29. The area seen before and after using AMSR2 sea ice brightness temperature, the animation runs from March 16 and everything has been very quiet, except strong sea ice drift that happened only for one or two days. The microwave image reveals neatly the weakened remain of the crack, will see what happens with it during April.

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