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Messages - seaicesailor

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1
Arctic sea ice / Re: The 2017 melting season
« on: May 28, 2017, 11:57:58 AM »
The surroundings of the small town are still cozily covered by a nice white blanket. The melting we see sometimes in the webcam is anthropogenic but of the local kind.
Image of Barrow from the sat yesterday

2
Arctic sea ice / Re: What the Buoys are telling
« on: May 27, 2017, 02:16:11 PM »
@Andreas Yes I plotted the red -1.8 C line as typical reference, but not implying that ice is melting as soon as the bottom water temperature is over that line. In fact no bottom melting seems to be happening yet. Thanks for the info on melting temp for that salinity Andreas.

3
Arctic sea ice / Re: What the Buoys are telling
« on: May 27, 2017, 06:43:30 AM »
@Hyperion not really, the interface does  not change within the noise of the data, not clearly. The www of the site does indicate a very slight bottom growth, if anything. I think that is going to change in any other day, being the buoy relatively in periphery location.
http://imb-crrel-dartmouth.org/imb.crrel/2017A.htm

4
Arctic sea ice / Re: What the Buoys are telling
« on: May 26, 2017, 04:22:09 PM »
The latest 6 days or so available of the B 2017A temperature profiles. I am showing the non-filtered data (red dashed line) and the filtered data. The result of filtering is that some spatial wiggling is removed, but also that the profiles take a 24h-averaged temperature approximately.

I think this daily-averaged temperature, for the thermistors not covered by ice or snow, is skewed to higher values frequently and I don't find another explanation that they are heated by sun or by the buoy material being heated by sun...

5
Arctic sea ice / Re: The 2017 melting season
« on: May 26, 2017, 03:24:19 PM »
This Terra 7-2-1 image is from yesterday, I believe some surface melting in the Beaufort sea corner near McKenzie Delta.
Today is pretty cloudy, no image yet;
Warm 2m temps above zero are supposed to spread from Canada into the Arctic for the next 72 hours.

6
Arctic sea ice / Re: Siberian Arctic coast
« on: May 25, 2017, 07:06:23 PM »
Intrusions of water from further East mixing with coast sediments?

7
Arctic sea ice / Re: The 2017 melting season
« on: May 25, 2017, 05:28:45 PM »
The ice drift for the next six days as forecasted by ACNFS, which I find always interesting (if presented at a speed the human can process).
Note the couple of days of rushing toward the Nares Strait ... will make for some interesting pics.

In general the ice continues its gradual slow tendency of drifting away from the Pacific.

8
Arctic sea ice / Re: The 2017 melting season
« on: May 24, 2017, 07:16:00 AM »
Thank you V. A. Kallio. This is really enlightening, most of us are used to the current "soup" and I for myself have not had a clear idea how things looked pre-2007.

9
Arctic sea ice / Re: The 2017 melting season
« on: May 23, 2017, 09:34:20 PM »
I was just considering the temperature anomalies for today over the Beaufort and the CAA.

Yes thats the warmth that got actually strengthened in the newest forecast, and will last for a few days.

10
Arctic sea ice / Re: The 2017 melting season
« on: May 22, 2017, 05:38:25 PM »
The CFS-v2 weekly forecasts tend to exhibit the same sort of "hot" bias that was identified for the GFS, in their forecasts 7-14 days in advance. I compare the forecasts for this week, which was done one week ago, against same forecast done this morning.


11
Arctic sea ice / Re: The 2017 melting season
« on: May 22, 2017, 02:58:18 PM »
While Ice Extent is lazing about right now, preconditioning seems to go strong - at least in the Beaufort, Chukchi and ESS Laptev, according to DMI ice temperature. Forecast for the next 3 days. The ice temps in the Amundsen Gulf and the Smith Sound should be taken with a grain of salt I guess though. Not much ice left there.

I would add ESS too, no hesitation. It is not having a cold start at all. Actually Laptev sea seems quite cooler but that can change in a blink it seems

12
Arctic sea ice / Re: The 2017 melting season
« on: May 21, 2017, 10:04:08 PM »
I think a visible light sat image of a blueish Hudson is no off topic here.

13
Arctic sea ice / Re: The 2017 melting season
« on: May 20, 2017, 02:19:02 PM »
The next six days of ACNFS ice drift forecast. Painful sustained for the ESS ice
EDIT. It won't work... trying to fix it.
No way. Today the system is in a mood and won't play the gifs correctly. Will try later

14
Arctic sea ice / Re: The 2017 melting season
« on: May 20, 2017, 12:20:40 PM »
.. meanwhile in the real world it remains anomalously cold north of 80' . This bit of the world has ignored all the 'hot' forecasts of the last couple of weeks . I know things will change .. except week 2 of the gfs forecast .. if it was real we would have been ice-free for the last 3 summers .
Not completely. The CFSv2 did forecast a cold CAB until third week of May included. The melt has reached Beaufort Chukchi and ESS coasts meanwhile (check Terra 7-2-1 carefully).
The GFS passed from a cold bias to a very warm one but the ECMWF has clearly diverged from it.
That the DMI 80N is in negative anomaly reflects more than anything the general circulation that, incidentally, keeps ice pack tilted toward the Atlantic. It can be read in many different ways.
I ignore the operational run of the GFS since ages (or try to, in favor of the EC), but the weekly predictions of the CFSv2 that ive been following this year have not been bad at all. This coming week however we'll see how warm things end up or not.
(BTW most of CAA, North Canada, Alaska, and Eastern Siberia snow cover melting as forecasted)

15
Arctic sea ice / Re: The 2017 melting season
« on: May 19, 2017, 07:10:09 AM »
Beaufort joined to Nares?
Yeah, when that breaks through, ice will flow freely from the Beaufort all the way through Nares. As we have seen, nothing yet has been strong enough to create a clog.

Everything is showing signs of melt onset, all over the Arctic now.

2000 km and in the worst case scenario that it doesnt close, 365 days, you are talking of 6 km / day, sustained.
A bit of a stretch.... especially when the ice in Beaufort typically flows in the opposite direction.
Cannot it come from elsewhere?
In 2007 the estimate was an outflow of 80,000 km2 or so. That is equivalent to a semicircle of radius 250 225 km approx. of MYI around the strait down the drain.
Or given the geometry around, a quarter of circle of 450 320 km. Isn't that bad?
Edit. Corrected the rough numbers

16
Arctic sea ice / Re: The 2017 melting season
« on: May 18, 2017, 10:41:19 AM »
I saw this surprising chart on Jim's site. I didn't think 2017 was tracking 2016 in this region, was quite sure it was lagging.
And just by inspecting 2012 in worldview you may add 2012 to the list of lagging years wrt 2016/2017 ... at least momentarily.
A consequence of this state is that the albedo potential calculated by Nico Sun, --- although remains second in aggregated, cumulative value, far from 2016, and in the middle of the bunch in aggregated, instantaneous value---,  shows negative anomalies along all coasts of the Pacific side (where melting by amplification of solar radiation absorption will be important) while positive in the Atlantic side (when melting by amplification of solar radiation absortpion loses some importance given the heat flux from Atlantic currents).

17
Arctic sea ice / Re: The 2017 melting season
« on: May 17, 2017, 11:46:49 PM »
The ECMWF mutated over the last couple of days and shows interesting changes and a fair disagreement with the GFS. Image below is the +120h latest forecast, not that far out. High-latitude snow-covered areas of the continents warmer in general, but the Pacific side esp the Beaufort sea won't be as warm as anticipated by other forecasts.
Coincidentally this is not in total disagreement with the CFSv2 forecast for this week. Then the CFS-v2 anticipated a comeback of strong HP for the following week, but I've got the feeling any model is starting to lose reliability beyond the 5 days as usual... We'll see

18
Arctic sea ice / Re: The 2017 melting season
« on: May 16, 2017, 06:54:02 PM »
Ice around Wrangel Island is no pack but a sea of ice cubes. Will we see the same in the central basin as the season progresses?
Yes, it may be broken in huge floes, but an unpacked pack in any case.

19
Arctic sea ice / Re: What the Buoys are telling
« on: May 16, 2017, 02:41:39 PM »
Making use of the same code as last year, but for 2017A.
I have placed the origin in what I believe is the thermistor at the ice surface, but I may be wrong. Anyway, that discontinuity is pretty clear.
I am afraid we'll have fun for less than one month with this one...

Great plot!
So maybe it began with nearly 20 cm of snow but had lost several cm of that by the end?
(Safe) Prediction: that remaining snow isn't going to see out the month!
EDIT: but wait..
Thermal conductivity of ice = 0.005; of water = 0.0014.
So ice has about 3.5 times the thermal conductivity of water.
Conversely, the same depth of water will show about 3.5 times the vertical displacement between the thermistors as ice. There must be some densely packed snow - almost ice but with some trapped air - that shows similar. And maybe that's what we are seeing from 2017A in March? How do we know if it melts? It just gets a little more compact in turning into water, with a similar displacement between thermistors. Perhaps that's what has already happened here - an alternative explanation?
Now I'm uncertain what is going on in that plot, but my apologies for the stream-of-consciousness post!
Thanks!
I don't know, I just tried to separate what varies smoothly to the right to what cannot explain its noise to the left. As said, might be wrong by centimeters but I don't think too much as there is a discontinuity in that y-axis, or the thermistor next to it.

20
Arctic sea ice / Re: What the Buoys are telling
« on: May 16, 2017, 12:10:46 PM »
I am afraid we'll have fun for less than one month with this one...
It takes more than a month to melt a meter of sea ice, especially at this time of year. However that doesn't preclude the buoy freeing itself from the floe long before the ice melts away completely:

Yes that's what I meant Jim. And it is getting located in such a bad place, with the heat coming. Like a bullfighter waiting for the bull in front of the gate (bad example, usually the bullfighter wins)
Anyway I am still in mourn for 2015F , lol

21
Arctic sea ice / Re: The 2017 melting season
« on: May 16, 2017, 11:35:31 AM »
That coming heatwave + open skies is going to do massive damage on the Pacific Side of the Arctic. And as soon as the Atlantic side comes into play as well, I expect 2017 to go low on all SIE and SIA graphs. The only question is whether it can overtake 2016 before it went up (end of June), or go a lot lower than 2012 before it started to drop very fast (end of July). Those are going to be exciting/interesting weeks.
A question I have Neven, how do you know when to expect clear skies? Is because of the dominant high pressure system alone or you see any other indication?

22
Arctic sea ice / Re: What the Buoys are telling
« on: May 16, 2017, 11:02:19 AM »
Making use of the same code as last year, but for 2017A.
I have placed the origin in what I believe is the thermistor at the ice surface, but I may be wrong. Anyway, that discontinuity is pretty clear.
I am afraid we'll have fun for less than one month with this one...

23
Arctic sea ice / Re: The 2017 melting season
« on: May 16, 2017, 01:48:07 AM »
The ice drifting away from Banks Island, the latest layer that had appeared shrinks while drifting. We can't be sure it is melting strictly speaking, it may be being compacted, what is sure is that is leaving room to open waters very quickly.

24
Arctic sea ice / Re: The 2017 melting season
« on: May 15, 2017, 06:10:59 PM »
I noticed that too. I wonder if there is a real physical phenomena behind this or is it an artifact of the measure.
Because it coicides with spring time and a weather pattern that tends to force cold wind across the Arctic Basin toward the Fram and Svalbard? It is not a exact science, but there might be a correlation. If the weather pattern is more frequent lately than in the past century...
Last year it did not cross but it was close.
Later in July August expect again negative anomaly esp this year with so much FYI... I bet! At least while we dont end up with a blue Arctic

25
Arctic sea ice / Re: The 2017 melting season
« on: May 15, 2017, 03:04:56 PM »
My apologies for posting almost thrice in a row.
Next two weeks, week-averaged values of MSLP (with anomalies) and T2M anomaly according to the long-range CFS-v2 model. So let's put more stuff and make the model fail bad!
Images courtesy of Levi Cowan at Tropicaltidbits.com
Week 1: There is a HP pattern relatively similar as past week (CAA-CAB-Greenland) although the blue color indicates that the highs weaken in average. Around this system, there is a ring of lows, especially close in Laptev and Alaska, that force similar circulation from America into the CAB and then toward the Barents sea. Strong wings over Beaufort coast continue for a few days according to ECMWF, but the CFS-v2 indicates that this pattern should gradually fade out, otherwise in average the map would not make sense.
Temperatures in Eastern Siberia, Alaska, and North Canada remain anomalously warm. I expect a big drop in snow cover this week in this areas, not just the following week.
For the DMI 80N lovers, it however may take some days for its anomaly to become positive again.
Week 2: The forecast of a high pressure dominating the basin is clear. However, how this plays later can differ a lot depending on the real positioning of the HP and its specific strength, if and how it couples with a low and in what direction...
In this case, the CFS-v2 predicts anomalously high temperatures practically all above the Arctic circle, (that is above lat N66 approx). Huge drop of snow cover overall. And I mean all, land and ice. Chilly in Europe and somewhere in the U.S.
Heck, I so much want to see this fail badly!!!!

26
Arctic sea ice / Re: Stupid Questions :o
« on: May 15, 2017, 01:24:34 PM »
Can someone point to a link showing the advective energy flows into and out of the Arctic, specifically the ratio of atmospheric versus oceanic?

Googled it and found these U. Colorado slides, a few of them put explicit numbers to the different energy fluxes, for summer winter and total. Perhaps it helps I didn't read it yet.

https://goo.gl/XJb3OD

Well spotted, thanks. The last few graphics at that site are pretty much what I was looking for.

Looks like the vast majority of advective energy comes from warm air.
Appears so and after this winter, well, it seemed overwhelming.
However note that their estimate dont add up, and they recognize this lack of closure in the problem
Big suspect is as always oceanic stuff (the hidden Lake Ness monster). I guess much more difficult to measure or estimate...
Really interesting stuff...

27
Arctic sea ice / Re: The 2017 melting season
« on: May 15, 2017, 01:09:42 PM »
Let's try using the long-range weekly CFS-v2 predictions. I bring the 1st and 2nd weeks of May. I will repeat this in the future only if these predictions really make sense (they did for April!)
According to these maps, 1. we should see some more drift in Beaufort sea this first week of May and the next. 2. During the second week, that dome of high pressure mentioned before, pulling heat from America and pushing ice toward the Atlantic.
3. Temperatures should be anomalously warm in Siberia, then we get the heat fro the American side associated to that high pressure system by the second week.4. Positive anomalies dominate, certainly in Siberia, 5. certainly not in the Central Arctic.
That the peripheral seas are warm especially the Pacific side does not mean it will be sunny. No cloudiness predictions here. 6. But polynya near the coasts should begin to stay open at both sides.
Note that these forecasts are mean values of different simulations, therefore get diluted with time.
Maps Courtesy of Levi Cowan - tropicaltidbits.com
Assessing how well the CFSv2 bi-weekly forecast worked out for the Arctic, I'd say it passed the test, at least the big picture that I commented. We've got first hints of surface melting in Siberian coast, wider leads and cracks in Beaufort that are not refreezing anymore, a lot of transport toward the Atlantic (the extent, with the permission of M&M, has actually grown and is at maximum values in Greenland+Baffin+Barentsz), the central Arctic has remained cold as shown in the DMI 80N, which makes sense given the pattern of winds.
I'l try to put together a couple of gifs of the forecast for the next two weeks this afternoon, although many good commenters are already giving the key hints of what to expect.

28
Arctic sea ice / Re: The 2017 melting season
« on: May 15, 2017, 12:55:49 PM »
The upcoming pattern being forecast by the EPS and GEFS (ensemble means of the GFS and ECMWF) are disastrous starting at D6. The CFSv2 has been hinting at a strong +AD type pattern at this time period for a while, but now the operational medium range models are on board as well. If these verify, it would serve to jump start the melting season and generate lots of late May melt ponding.

May 31 - high pressure and only small areas below freezing. Image: tropicaltidbits.com
Interesting, but disturbing.
The surface melting / melt pond radar wake up this morning. From the time being, clear change in the blueish tonality of the 7-2-1 Terra images brought to us by the still working NASA. I put a transition of image from April 30 directly to May 15, to better appreciate the change.
Not sure, but I think from other years what we are watching is rather wet snow over the fast ice, plus some fresh water pouring at the coasts, result of the melt of adjacent hills and mountains, that are showing bare of snow in some places near the coasts.

29
Arctic sea ice / Re: Stupid Questions :o
« on: May 15, 2017, 01:15:43 AM »
Can someone point to a link showing the advective energy flows into and out of the Arctic, specifically the ratio of atmospheric versus oceanic?

Googled it and found these U. Colorado slides, a few of them put explicit numbers to the different energy fluxes, for summer winter and total. Perhaps it helps I didn't read it yet.

https://goo.gl/XJb3OD

30
Arctic sea ice / Re: The 2017 melting season
« on: May 12, 2017, 10:35:00 AM »
When I pointed out this opening a week ago, the many "Experts" sent me to the Nares' thread.
Basic physics & common sense seems better guidance than peer- reviewed, paid-for-and-politically-filtered Articles.
https://forum.arctic-sea-ice.net/index.php/topic,176.msg101527.html#msg101527
People have been showing us this since January, that's why people sent you to that thread... But Tigertown animation of its collapse is really pertinent to this thread. This opens now another venue of escape of (old) ice toward the Atlantic.
But I am not really sure how unusual this is overall, since I don't follow the Nares opening dates.

31
I think I'm going to earn a position of target of some criticism and unfriendliness, but I've got the impression that some of you people are selectively ignoring facts:
- It is true that the Pacific sector has a very bad color. Nevertheless, the Beaufort Sea (key in the destruction of ice) has only come to a modest start. More importantly, the Beaufort Sea has ended a lot colder than last spring. See how fractures are frozen as soon as they are opened and we are on May 11th. The refreezing came very late (December) with the loss of ocean heat that this entails. Not only that, the snow has generally been scarce in the area, so ice has nicely thickened reaching up to three meters (see Piomas, Cryosat).
- We are waiting for a heat wave that some members are announcing since April. Be not disappointed, if it does not come. I put the chances at 50% that heat will be maintained during the month of June, that's the key. Why? Because the deposited snow on the continents, not only in Asia but also in America, broke all sorts of records, perhaps caused by the extreme deviation of the Arctic Autumn and the Winter. Could this not cause a cooling effect in the summer weather? Seems a bouncing oscillating effect that is not nuts at all.
- The extent is in normal values ​​of the 21st century, far from the lowest data from other years. Do not forget one thing: the extent and the area are very important to give a boost to the melting season or to inhibit it, and the critical time now begins. The albedo potential maps just show that the anomalies in the Pacific (relatively unimportant) are canceled out by the anomalies in the Atlantic (relatively unimportant), with anomalies in the Arctic proper that are just irrelevant for the time being. The brief time of change must come.
- Volume also rebounds

It's still early to forecast (also on volume), I'll wait as much as possible to make a prediction for this poll, to have a clearer judgment. A very strong heatwave must come, when it comes, if it comes, or if it doesn't, I will put my vote or just comment about it if the voting is closed.
I think we all agree on the importance of extent (or area) on early melting etc. But (allow some criticism),
- Understood about Beaufort sea (kind of shaken though), but what about that void over the Chukchi sea??
- Anomalies of albedo relatively unimportant over the Pacific?
 - Sun warms water near Bering strait
 - 100% chances the water enters the Arctic during spring and summer, it tends to happen
 - Warm water melts ice more than cold water

Agree with much of the rest, although land snow could be a source of heat in June when discharging after melting, as has been pointed before esp if warm weather.

I keep my vote of August momentarily :-)

32
Arctic sea ice / Re: The Slow Transition
« on: May 11, 2017, 10:57:24 PM »
Sorry, SIS, if I inadvertently used your post to support a stance you do not hold. 

I've stated that I've valued reading Chris's analyses on this Slow Transition topic but that I wasn't convinced by it.  I have also long considered the 'quick' loss of summer ice in the non-CAB regions over the past 30 years (e.g., the Beaufort going, in August, from 2/5th coverage to none between 2013 and 2016) not to be predictive of how fast CAB ice will be lost.  I think this discussion of bathymetry adds some geophysical creds to Chris's theses.  This doesn't mean, however, that I'm 'now' convinced Chris is right.  I think other issues like CO2-equivalent, mobility and storminess may well 'over' compensate for the bathymetry-related suppression of warm water currents remaining near the ocean surface.  This is all just more food for thought.
No reason to apologize!
It is in fact a limiting factor and can support a slower transition to ice free Arctic, but, it seems not very resistive to me... Meaning: whenever the ice edge (not just broken floes) has advanced into the CAB early enough since 2007, we have seen amazing runaways (perhaps helped by winds as commented by DoomInTheUK). 2014 was disappointing for many but the Laptev bite evolution made an impression on me. Why? That bite had started "chewing up" ice in May while the rest was rather cold. I am really curious to see what happens this year.

33
Arctic sea ice / Re: The Slow Transition
« on: May 11, 2017, 03:58:24 PM »
Not completely  or at least not me... the transition of plenty of MYI in 2007 to no MYI (in practice) in 2017 has not been slow, and my original post just wanted to reflect on how much less energy is needed to heat the mixed layer to start bottom melting in the absence of MYI (heat equivalent to melting 70 cm of ice after Bill Fothergill correction).
But the bathymetry  (or is it bathimetry) issue arised, as a limiting force against a total meltout. I have not a settled opinion based on lack of knowledge about it.

34
Arctic sea ice / Re: IJIS
« on: May 11, 2017, 02:33:22 PM »
Ancient tools... are you talking about the sextant, or an apparatus mounted on a satellite?

35
Arctic sea ice / Re: IJIS
« on: May 11, 2017, 02:31:32 PM »
extent doesn't tell us much considering the farctured ice conditions and the mobility that was mentioned above with the effect that we in parts find MYI in places where last year for example FYI was melting out upon arrival. there will be a very sudden drop later on but anyhow, i strongly believe that we should shift focus away from extent to volume and in parts area at this time of the melting season. we're all too much used to things and how to do/use them while things have changed dramatically and ancient tools and procedures are not only becoming useless but at times start to be misleading.
I'm just saying that the 700k or so that 2017 lags behind 2016 are located in Barentz, Greenland, and Baffin. Is it against the law? (in a ice-extent-dedicated thread)
My friend M&M you show some nerve...

36
Arctic sea ice / Re: IJIS
« on: May 11, 2017, 08:22:02 AM »
There is not much MYI in the Barents Sea, only up against Svalbard. There is probably about as much MYI in the Barents as there is in Baffin Bay, which is to say not much.

http://www.aari.ru/resources/d0015/arctic/gif.en/2017/20170509.gif
https://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

Right, just checked Cryosat thickness and Barentsz is bound to meltout unless something happens. Baffin always does and Greenland sea is the one with indigestion  (as is the area north of Svalbard)

37
Arctic sea ice / Re: IJIS
« on: May 11, 2017, 07:38:59 AM »
From Wipneus extent graphs. Even Baffin shows an uptick in the JAXA-based curve (in purple)
Edit. Only from these regions I notice 600-700k of excess with respect to 2016, and we're not counting the excess in the CAB (no clear Atlantic front, yet).Will this be a story in 2017?

38
Arctic sea ice / Re: IJIS
« on: May 11, 2017, 07:24:36 AM »
To prove that the theory not always works and the devil in in the details: the AO is -ve, the NAO is -ve and the PNA is +ve, yet the extent upticks in May and 2017 gets lost in the middle of the other recent years.
This is the MYI not melting out in the Atlantic front and Barentz momentarily. On the contrary, more ice is being pushed toward the Atlantic Ocean  due to the prevailing circulation.
That the extent is relatively high is not so relevant, but whatever it is its tendency will be in a couple of weeks though, to trap more solar radiation or not.

39
Arctic sea ice / Re: The 2017 melting season
« on: May 11, 2017, 12:20:21 AM »
Aaand sorry for overposting but couldn't restraint myself.
Nice dipole, staying for about a week with more or less strength, our prime suspect of dragging the heat and pushing things around...

40
Arctic sea ice / Re: The 2017 melting season
« on: May 10, 2017, 11:37:07 PM »
Second attachment: NCEP polar ice drift 7 day forecast.

http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=POLAR&area=POLAR&ps=model#

To complement this, according to ACNFS there are still three or four days of localized but strong drift out of the Amundsen Gulf, also two days of strong drift northwards over Bering strait and Chukchi sea. It isn't over yet

41
Spring (April) volume explains about 45% of the variance at minimum. So, while it's not a guarantee that we get a record low volume, the dice have been loaded in favor of that outcome. Obviously, the late May to late June pattern is coming up and that will account for another big chunk of the variance. We'll know soon enough -- probably by the end of this month (since ensembles can reach out about 10 days ahead on the large scale pattern).

Naive (really) question: shouldn't the CFS be apt for these 10-15 day forecasts of the general circulation? Since the CFS simulates not only the atmosphere but also the ocean evolution and its interaction with the atmosphere, including its own ice model.
While the ice model has shown no skill whatsoever on the long run over the years, the ocean SSTs and ice evolution within a few weeks could be beneficial for the simulations.
I say this since lately I have been posting here CFS plots by tropicaltidbits like every two weeks. Seems pretty reliable since March...
What do you think?

42
August 9th is a good choice :-)

43
The minimum of minima (MoM?) will also be influenced by the trans polar drift.
That might give a clue as to why the ice edge tends to be closer to the drop off on the Atlantic side and further from the Pacific. It's a trend in the data.

Just a thought.
Completely right. Providing that observed offset toward the Greenland sea. And the Gyre combined with the "ice slaughter" of Beaufort sea explains the void in Beaufort and Chukchi seas.
Pending the question of how far the ice edge can retreat due to heat amplification inside the core of the CAB - aside from the effect of wind drift. Ocean currents unable.

To me it all boils down to having a very early generalized surface melting and propagating melt front.

And the ace card of the summer (the GACs).

44
Looking at the bathymetry image above I'm struck by the course agreement of the ice edge and the continental slopes on the Siberian and N.American sides. So I suspect some relation, perhaps it takes that far for any internal and gravity waves to dissipate enough not to disturb the ice?
Sorry ot.
Well this went OT by me that I opened the thread and it's all fine since I like the issue.
I don't question the importance of bathymetry. Atlantic currents that enter east and west of Svalbard, and north of FJL and into Kara sea travel shallow waters, but do not stay close to the surface once over the Arctic basins. They sink as soon as they reach the shelf boundaries into the Arctic basins.
That puts a lot of heat away as we all know (or learn).
I dont know as much about gravity currents, but in any case the tendency of warmer & saltier water to sink down the continental slopes is there all around the Arctic.
Still, look at the minimum of minima extent and notice many kilometers of penetration of the ice edge away from the warm currents inside or above the basins, particularly in the Pacific side.
As I said, this could be an excellent year to test the limiting force of the bathymetry in the reach of the ice edge. My feeling is that if melting propagates early by albedo feedback, sun radiation can force the edge ahead to the north pole, and we have never seen that yet.

45
Arctic sea ice / Re: Arctic Image of the Day
« on: May 10, 2017, 12:27:28 AM »
It broke big in fact. :-(
So nothing remotely close to BB in size this year (needless to say not in thickness or age...).

46
Arctic sea ice / Re: The 2017 melting season
« on: May 10, 2017, 12:21:25 AM »
The heat wave in Eastern Siberia is going to be memorable in a week and for a week, if the CFSv2 and GFS and ensembles realize, (and the CFSv2 has been working really well,  and btw has been predicting this for weeks).
Alaska and parts of Canada/CAA too. Wall-to-wall

47
Alright. There are many sorts of currents. Yes currents are complicated but there is an unavoidable tendency of warmer saltier water to sink in the presence of colder fresher water, and that happens at the big slopes of the Basins of the Arctic Ocean. That this colder fresher water exists on top of it all is one interesting thing, which seems to me is not going to change in one season, and therefore I don't believe in any blue ocean event anytime soon. What seaicesailor has depicted in red looks to me as a very reasonable boundary of a very bad season nowadays. Warm currents cannot melt ice over the main Arctic Basins (the Canada Basin is a special case that we can discuss at length).

May I speculate that you just recently learned about the bathymetry of the Arctic Ocean and implications on oceanic inflows and outflows... and you changed your mind about blue ocean events just as recently? See below (sorry for doing this but couldn't help after you mentioning again the curve I plotted above, that does NOT represent any minimum extent in particular:-/ ).

[...]
If we do happen to see a 2007 type summer, I could see us losing all we have there in one go. Why? I do think that the thick ice that is currently there is nothing more then contaminated salty ice that under 2007 or 2012 type summer will vanish in a flash because there is no solid structure to that ice.
Without knowing the whole story of 2007, only partial bits, a scenario like you describe seems entirely reasonable as leading to the first summer virtually without ice. This is my expectation if such weather comes

Edit. By the way I discussed about this last year mentioning an Arctic Sea Ice News article

https://forum.arctic-sea-ice.net/index.php/topic,382.msg84116.html#msg84116

You may want to read the article, as it is out of the question bathymetry has a large influence.... (but inconclusive, as I am because it is a very complicated matter... maybe we will learn something this year).

Edit edit. And even more interesting this response by Bill Fothergill
https://forum.arctic-sea-ice.net/index.php/topic,382.msg84153.html#msg84153

And this by Rob Dekker
https://forum.arctic-sea-ice.net/index.php/topic,382.msg84140.html#msg84140

48
Arctic sea ice / Re: The 2017 melting season
« on: May 09, 2017, 01:34:54 PM »
...
I think I am going to move this to a separate thread
...
- The energy for raising 1.8 degrees 30 m of water is equivalent to that needed for bottom-melting approximately 0.75 m of ice!!!! (since raising 1C of a 80m-deep extent of water requires the same energy to melt 1m of the same extent of ice)
...

NB I will move my comment over to the appropriate thread once you have set it up.

I was going to mention that the density of ice is less than that of water, but you appear to have already included that in order to get to the 0.75 metre value.

(30/80) * 1.8 would just give 0.675 metres, but if the (relative) density was taken as ~ 0.9, that would give your figure of 0.75 metres.

I think your x80 multiplier would only be appropriate for fresh water. The SH of sea water varies somewhat with salinity, but is roughly 3.985 kJ.kg-1.K-1, as opposed to the 4.186 kJ.kg-1.K-1 value for pure water. {I am assuming you are using a value of around 333.5 kJ.kg-1 as the enthalpy of fusion?}
...

Bill thank you very much for the correction. Yes, there is a new thread
https://forum.arctic-sea-ice.net/index.php/topic,2030.0.html
And it has drifted unexpectedly to another physical problem, perhaps you have a say in that too. :-)

49
Indeed! You are supporting me in my claim that the bathymetry is likely to prevent the so-called blue ocean event for many years. That red line you have drawn so clearly follows the bathymetry of the Atlantic side. ...

Indeed, I like your plot, that represents the ice edge as I imagine it at the minimum...

You did not read my comment carefully, no I don't support your claim! Ocean currents help in melting peripheral sea ice, but you can see the ice edge (as conservatively as defined by the NSIDC) has retreated thousands of kilometers above deep ocean in past seasons, and in the Atlantic side (2013; 2014 Laptev bite) and in the Pacific side.
But if you like the map as your theoretical minimum minimorum of a bad year, well all yours. But that was not my intention.

50

Good exercise. However, we must not forget that there are ocean currents in the Arctic that help spread that energy. And those streams end abruptly in certain areas of the Central Arctic as a result of the oceanographic topography. In other words, the ice can melt a lot from this distribution of energy, but upon reaching a certain high latitude, the flow is off. Coincidentally, the albedo feedback too. Note that we are talking about the central Arctic, which will be frozen and cold until August.
Not so sure about how much the bathymetry plays a role, everything has a limit.

This plot an envelope-curve, a minimum of minima of September NSIDC extents. I have taken the ice edge for every year minimum and kept only the edge of each year that is closest to the Pole. I only needed from 2016 back to 2007. Before that year, all the ice edge at September fall out of the curve below.
To take into account that
 - NSIDC September extent is very conservative due to the weird algorithm they used
 - There have been regions in the past with a very low concentration of ice (for instance 2013 near the Pole) that however will never be reflected in these minimum extent ice edges.
I agree that ocean currents help the ice retreat every year, and these currents that are warmer in the continental shelves then sink, BUT you can see that some years have put the edge of the ice well over deep ocean... by hundreds (even thoushand) of kilometers


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