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Messages - subgeometer

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1
Arctic sea ice / Re: The 2017 melting season
« on: April 23, 2017, 03:27:30 PM »
Thanks for the animation. ~700 pixel width is the trick.
And, are you sure it's a current and not wind-driven? If it's a current it's really bad news.

Ther looks to be melt on Asian side going thru Bering strait last little while, so I was thinking the same thing. Someone else also posted a sst animation that suggested that as well

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But past Wrangel Island is a long way, there's no melting goodbye waves in that polynya

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2
Arctic sea ice / Re: The 2017 melting season
« on: April 21, 2017, 09:57:43 AM »
The Bering and Chukchi from April 15-21 with april 19 2016 by way of comparison. Doesn't look good

3
Developers Corner / Re: Creating Animated GIFs
« on: April 20, 2017, 05:02:56 AM »
If running linux or unix ImageMagick is a ubiquitous tool suite for image processing. On Ubuntu at least it comes as part of the standard install. It runs from the command line so is easily usable in scripts for batch processinga

The main tool is convert

A simple shell command to make a sequence of stills from image_1.jpg to image_n.jpg into a gif is

convert -delay 100 image*.jpg the_movie.gif

or

convert -delay 100 image_1.jpg  image_2.jpg  ... image_n.jpg the_movie.gif

The delay parameter sets framerate as milliseconds per frame(I think)

convert can do many other things besides, a swiss army knife for scaling, compositing, image generation,adding text etc . It's fairly well documented online though its manual is somewhat terse

4
Arctic sea ice / Re: The 2017 melting season
« on: April 20, 2017, 04:33:16 AM »
subgeometer
Is there a thread where image retrieval and animation are discussed?

Yes, to the animation part, anyway.

http://forum.arctic-sea-ice.net/index.php/topic,1259.msg89520.html#msg89520
[/quoTigertown

5
Arctic sea ice / Re: The 2017 melting season
« on: April 19, 2017, 08:55:27 AM »
A view of the area south of a line between FJI(top left) and Svalbard(bottom left} from april2-18 shows the smashed up pack that has been pushed out into the Barents blowing back and forward and melting - with huge area of melt - 100km deep at times on the margin

I've included a larger still from April 8.

The area is going to cop a fair bit of wind from about 48hrs out  for a day or two. The wind will also be pulling away from the Siberian coast during its heatwave

(One interesting feature of worldview is that images downloaded thru its 'camera' interface have the date encoded in a TIME parameter in the url as the year and day in a n integer as YYYYDDD - eg April 12 as 2017102 allowing easy retrieval of a region (etc) over a period either in a browser or with a script - Is there a thread where image retrieval and animation are discussed?)

6
Arctic sea ice / Re: The 2017 melting season
« on: April 05, 2017, 11:50:57 AM »
High pressure has come too late to thicken iced and if it persists into May and June that won't be good, though it's getting harder to imagine weather that will be good for the ice given the heat in the system.  A cold cloudy still summer maybe. The band 31 images JD posted a few days showing much greater warmth on the Russian side are alarming, is it just due to the very thin ice there or is the current from the Atlantic also being mixed more with the surface

Ice is an Esky on a hot Australian Christmas will seem hardly to melt for ages then be gone in minutes, I fear we might see enormous extent drops later in the season given all this dispersion and 1m ice in Beaufort, wafer thin in ESS etc. We've only just passed the 1.5m mark in new ice growth above 80N according to Lebedev

7
Arctic sea ice / Re: The 2017 melting season
« on: April 04, 2017, 12:53:18 AM »
Are the purple and mauve areas inside the 85 deg latitude, indicating 400 – 500 mm of thickness for real?

Or are they a false reading at the edge of the scan for some reason?

I think the spots around the pole hole are noise, there's generally a random spattering there

8
Arctic sea ice / Re: The 2017 melting season
« on: April 02, 2017, 12:57:09 AM »
I think "pushing" to be a good choice of wording for this side of the Arctic. Navy HYCOM shows an increase in drift, which no doubt pushed the ice in this direction faster than it could melt. You can see a shift throughout the pack in concentration toward this side. So it is definitely not to be confused with growth or refreezing.
CLICK IMAGE      25th vs. 31st    (side by side below)


The ice is pushed out rapidly between FJL(at top) and Svalbard on this Worldview animation of March 19-april1 - the expanse of open water behind FJL grows 100km in a matter of days

The second attachment is a larger version of the same images which better show the state of the ice - the floes are like flat pebbles, corners ground off and of all sizes


9
Arctic sea ice / Re: The 2017 melting season
« on: April 01, 2017, 12:32:30 PM »
That snow is going to melt pretty fast this year....dont see it lasting... and record volume was very warm ground due to insulation...

GFS is showing substantial snowmelt in the MacKenzie and Ob catchments over the next week

10
Arctic sea ice / Re: The 2017 melting season
« on: March 30, 2017, 04:04:57 AM »
These cracks or shears or whatever are spreading and getting worse. They have no respect for the NP region either. Only the the thick, robust, durable, mighty, 93 cm ice in the Beaufort stands a chance against these. ;)


Hee''s an animation of the ESS from March 11-29 where the Bremen Thin Ice map at https://seaice.uni-bremen.de/thin-ice-thickness/ has been showing a persistent region of thin ice. Despite the ice pushing away from the Eurasian coast it's not apparently thickening up much else where, and the ongoing heatwave on the Eusaian side will not allow much new ice growth

11
Arctic sea ice / Re: The 2017 melting season
« on: March 15, 2017, 12:00:09 AM »
The GFS forecast shows rain areas in the Kara Sea every day for the next 5 days.

12
Arctic sea ice / Re: The 2016/2017 freezing season
« on: March 04, 2017, 02:23:52 AM »
GFS forecasts a return to big positive anomalies  in just under a week with a pulse of warmth entering from the Pacific. And daytime temps are becoming noticeably greater than night in the more southerly areas of the Arctic basin like the Chukchi sea

13
Arctic sea ice / Re: The 2016/2017 freezing season
« on: March 02, 2017, 01:23:32 AM »
A lot of persistent thin ice is still showing, including an almost continuous strip all the way from Svalbard to the Laptev Sea.  Which is along the path of the warm Atlantic current, no? And according to GFS the next week will have winds continuing blowing ice away from the Russian coast. While that ice will undoubtably ridge and thicken somewhere else, giving volume a bit of boost, how much of that is destined for the convergence zone where ice is packed for export via the Fram?

The Beaufort a way offshore from the MacKenzie is also under .5m thick, and has been for a while. The area has been shrinking for a few days then expanding again.

I've attached a couple of animations of Crackopalyptic events in Laptev and Beaufort in recent days. The cascading shattering in the Laptev looks particularly interesting. They'll need a click to animate, files are a bit large

edit: the date ranges are 20-28feb for the Laptev anim, and 23-27feb for the Beaufort. (Unfortunately this computer is running from a live CD with no image editor or otherwise I'd add the dates to the images. I'll have something more capable soon)

14
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 20, 2017, 01:37:31 PM »
Will the temperature above 80 make it to the baseline? Maybe the circled "hot" air intrusion delays it a bit, but it looks good so far. This late freeze might give us the head start needed for the melting season.
It doesn't seem like temps will go much below the old average for tthe date,, whereas big cold anomalies are required IMO, And if high pressure lingers more than a month, it won't be good - the sun will be higher in the sky

15
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 19, 2017, 01:22:46 PM »
That gives a glimpse of the old CAB. All that export, and yet concentration and volume both are growing. I don't have any false hopes that it will last, but it's good for it to have at least one last hoorah for the season.

While I don't doubt volume should increase with the colder weather I find it hard to believe volume is greater than this time last year when FDDs this season are 20% lower than at the same time last year, at least above 80N. Could all the snow on the ice be fooling the instruments?

16
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 19, 2017, 12:10:37 AM »
Thanks Aslan.

Meanwhile the thin ice map from Bremen is looking terrible, with sub 0.5m ice everywhere from the Laptev to Hudson Bay, including around the pole hole

17
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 16, 2017, 01:20:50 PM »
I wonder what the forecast cold weather is going to do the trend line on the FDD charts.
We can hope, but FDD anomaly is already greater than any other year, so it would have to get really cold for a while to even be in a better position than last year

And looking at the fragmented ice steaming through Bering St (from 14-16feb)doesn't fill me with confidence, and Chukchi doesn't look that great either - click to animate

18
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 15, 2017, 01:03:27 AM »
Northern Hemisphere snow cover has started to go down:

Over the next week the GFS forecasts loss of snow cover in a broad swathe of southern and central Canada especially the upper half of the MacKenzie catchment across to southern Hudson Bay, and also  in eastern Europe.

The big heat anomalies move to the midlatitudes of the continents, perhaps at just the wrong time

19
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 11, 2017, 02:33:09 PM »
Climate Reanalyzer shows nice eye forming just south of Svalbard next Saturday. Winds 110 -130 km/h and pressure 944. Not too friendly for ice edge.

That looks ugly, and just where it can stir up the warmest waters. Before that Bering Strait and sea is looking at 3 days of over 60k winds blowing out the strait from about 84hrs in, Which can only thin the ice out more and there are already areas of sub 0.5m ice in the Beaufort and ESS according to Bremen SMOS

20
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 09, 2017, 04:23:12 AM »
wow, huge areas of goodbye waves in the Bering Sea today.

21
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 09, 2017, 01:42:56 AM »
The southern Kara sea is now visible on Worldview, not looking great . Nor is the Bering Strait.

According to GFS the Bering and Chukchi will see a lot of wind later in the next week, favouring export and peaking at over 60kmh . At the same time wind will be pushing the Atlantic side straight towards Svalbard and doom

So we may see some extent increases!

22
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 05, 2017, 01:49:50 AM »
It is getting late into the evening where I am, and I just looked at the most recent images available.
I had looked at everything this morning, and from what I remember, I can honestly say that most of the ice looks worse now than this morning. I wish that I would have dl'd the ones this morning; may have to make that the new morning routine. That's getting pretty bad, when you need to compare images from the same day.



P.S.  I did get a good clear picture of the Bering Strait this evening.


The stream of melt to west  and north of St Lawrence Island is pretty striking

23
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 03, 2017, 02:53:46 AM »
I have processed historical FDDs at 3 degree increments, both lat. and long. over one quadrant of the Arctic.  The difficulty is in presentation for me.  Perhaps this will elicit some suggestions. 

Notable, other than the large drop for 2016, is the even larger drop approaching the Chukchi.

One could create a map of the basin with the sector borders marked which brought up the graph for each sector as the pointer hovers over it , with an interface to allow creating larger regions out of the sectors. That seems to me like an intuitive way to browse the data

24
Consequences / Re: Global Surface Air Temperatures
« on: February 03, 2017, 02:51:05 AM »
Sorry for the OT, I misdirected myself

25
Consequences / Re: Global Surface Air Temperatures
« on: February 03, 2017, 02:49:30 AM »
<quote

I have processed historical FDDs at 3 degree increments, both lat. and long. over one quadrant of the Arctic.  The difficulty is in presentation for me.  Perhaps this will elicit some suggestions. 

</quote>
Responding to Cognitive Bias on the freezing season thread (https://forum.arctic-sea-ice.net/index.php/topic,1611.msg101593.html#msg101593}

One could create a map of the basin with the sector borders marked which brought up the graph for each sector as the pointer hovers over it , with an interface to allow creating larger regions out of the sectors. That seems to me like an intuitive way to browse the data


26
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 01:09:51 PM »
Speaking of drift, after about 4 days on the GFS forecast winds turn around for several days to promote more Bering St export

27
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 10:40:20 AM »
TT admittedly my knowledge is limited but the moisture forecasted to arrive with all that heat from both sides over the next week( at least) seems really impressive

28
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 10:24:01 AM »
SlowWing From watching forecasts over the winter my impression is FDDs have been closest to normal in a strip from the New Siberian islands to CAA in centre of the basin

ie far enough away from Atlantic and Pacific warm air intrusions

29
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 01, 2017, 06:45:39 AM »
2 worldview images of the same region of Bering Sea on 24Jan and 31 Jan - a rectangle from about 61.62/-168.7 to 62.2/-172.9/.

A lot of melt in the 2nd image

30
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 01, 2017, 02:17:30 AM »
Yes, it would be nice if the dmi-graphs were centered on winter. Summers at +2m ASL can't rise very high as long as there's ice to melt. Cut and overlaid 2015-16 and 2016-17 winters, but as Neven said the FDD shows quite a deviation. Not that it does not show on this too.

Displayed like this the change at Christmas 2015 is very clear. Since then, in addition to the outrageous spikes, temperatures haven't been able to fall to the average, let alone below, as if there is a floor at 247K

In the old regime there are also temp spikes, not so common maybe, but in any case they couldn't raise the temperature to the levels we see now because the baseline temperature was so much lower, like in this chart from 1961

31
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 30, 2017, 09:28:22 AM »


Hello, I'm a newcomer. Hopefully this is the correct thread to post the following.

Freezing Degree Days north of 80N have broken low records by extraordinarily large margin this freezing season. While the ice volume according to PIOMAS is record low, the margin is not that extraordinary. I haven't looked at any tabular data, just from these two graphs:

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1_CY.png
http://4.bp.blogspot.com/-qDBudaFi7CU/WIrFS1xO1dI/AAAAAAAAARc/vvxOPIit5w0Hj5r7j1xpJxKPpdRgzWCTACLcB/s1600/Total%2BFDDs_1_26_2017.png

From those, I made this crude graph. Blue lines for the freezing seasons 2010-11 to 2015-16, red line for this season until December, and the red circle for the position, near which January figures are likely to be.



The relationship between FDD and ice growth this winter is much different from previous six seasons. Is a greater percentage of ice growth occurring south of 80N, or is the heat transfer coefficient north of 80N extraordinarily high? If latter, why? I don't see how the general decrease in thickness could have increased the coefficient so much. A more uneven distribution of ice thickness? More fractures in the ice, exposing more open water?

And if the heat flux from ocean is enhanced by such factors, how big is the role of this enhancement in maintaining those extraordinarily high temperatures?

Thanks in advance.

Welcome to Neven's forum, elioe!

I think the FDDs (or lack thereof) affects thickness/volume more than area/extent.  Calm sea water and approximately -10o air temperature will freeze the ocean surface, but such 'warm' air temperatures will not thicken the ice very much over the winter. Others know something (and I know virtually nothing) about the formulas associated with ice thickening and air temperature.  They may be the ones to really answer your questions.


Given the newly open water on Atlantic side, has the temp anomaly above 80 North been greater than deeper in the basin? From memory it seems that way. That could explain the greater volume growth per FDD. There was a arctic basin temp chart on the google arctic sea ice graphs page but it has been displaced or removed

32
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 30, 2017, 01:23:40 AM »
Model are currently showing an extreme arctic warming event from both the Atlantic and Pacific sides for Feb 3rd.  In this image it shows nearly 1/2 of the cab at ~(negative)4C surface temperatures.

edit, sorry it was -4C not +4C avg temps.  just saw that.


GFS is showing above freezing temps in parts of the ESS on Feb 2 . The heat comes with a firehose of moisture, over 10kg/m2, carrying its own latent heat. Later in the run another big pulse comes in over Svalbard.

And the weird donut in the geopotential map persists centred on the Bering Strait and Chukchi Sea for days

http://cci-reanalyzer.org/wx/fcst/#GFS-025deg.ARC-LEA.GPH500-MSLP

33
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 30, 2017, 01:00:28 AM »
Those cracks above  FJL remind me of how a perished fabric frays along the grain when tension is applied across it. The furthest north on ATeam's animation is a long way into the pack, which appears to have the strength of wet toilet paper.

DMI 80 North temperatures haven't fallen below about 247 Kelvin for over a year now , ie 5 above the old average. Is it ever likely to do so again? The open water even in winter where all was ice before must play a part.

The area around Svalbard hasn't frozen at all despite the FDDs, because of the warmth of the advancing current there. With the warm salty water also under the Arctic, which already seems to have been stirred a little, I'm worried that a winter blue ocean follows fast on the heels of a summer meltout, in just a few years

34
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 28, 2017, 01:56:13 AM »
No ESS yet but Worldview has pictures of the Bering Sea. On 24 Jan the Ice can be seen through the clouds, with a lot of melting ice at the front.

The first is a section centred around 60north and 170 west, the second a wider view showing the strait

35
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 27, 2017, 02:36:59 AM »
I'm no expert but this geopotential forecast that goes along with the coming intrusion of heat looks really odd. The warm area is also ringed by a 'bubble' off the jetstream. It's still a few days away, but the last 3 days runs have been pretty consistent about this.

Is the winter troposhere going to turn into a donut around the pole when the Ocean goes blue?

36
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 27, 2017, 12:24:43 AM »
Talk of proper seasonal cold returning seems premature to me. The ESS looks to be expecting above freezing conditions in 5 days or so, combined with a massive plume of moisture

37
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 26, 2017, 01:36:19 AM »
According to GFS, in about a week a hammer blow of heat and moisture is coming from the Pacific side.

That can't be good for the Bering Sea Ice, or Chukchi etc


38
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 18, 2017, 03:31:27 PM »
This thread is a fantastic unfolding history of this storm & epochal freezing season but by nature is somewhat messy.

OT comments and discussions irritate and disrupt, but the line is grey because of the uncertainties, incomplete understanding and data, uncharted waters. And we all have different levels and scope of knowledge. Wayne's critique of obsolete measures like extent was dismissed by many as a crazy pet theory not so long ago.

I think once the season is historic some editorial post production could create a more usable resource alongside the source thread

For example, a page dedicated to techniques for extracting compiling and displaying relevant data like sentinel, weather, etc, with any scripts

Breakouts of various discussions that turn out to be important, referenced to or quoting important relevent contributions on other threads, as well as important events like the current storm.

Who would do it? I'm guessing Contributors of the calibre of ATeam will be too busy to more than consult because there seems no way events will slow down, perhaps a postdoc could assemble a group? As an artist my skills aren't right, and my resources too slim now.

The perhaps outlandish pet question now is whether the loops in 250mb jet ushering the stormsvto the ice edge will become a spiral or pair of sspirals in winter once the black swan fully appears in open waters in the central arctic



39
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 18, 2017, 02:40:02 PM »
A-Team

Earlier years show spikes in DMI 80 north temp charts, only from llower baseline temperatures, likely warm air coming from the oceans. I guess the effect would be to slow ice growth in those all too recent days except at the former edge, now open sea.

Would there be ice thickness data etc to serve as a kind of control?

40
Arctic sea ice / Re: The 2016/2017 freezing season
« on: December 18, 2016, 09:47:45 AM »
... the majority of the sea ice comes up at 66 cm for the heart of the Arctic with obviously lower thickness on the fronts and the thicker near the CAA.

Yes, most estimates I see are close to that which can be calculated from DMI temps using Bilello's formula.  The graph would become too 'busy' with both Lebedev's and Bilello's estimates on it and that's why I chose to add the 1m, 1.5m, and 2m indications per Bilello.

Neither formula is new; Lebedev dates to the 1930's and Bilello to data collected in the 50s and 60s -- though he published the formula in 1971.

A question: If a mobile pack leads to more mixing of warmer water from below thru Ekman pumping, how much effect does this have on ice thickening?

41
Arctic sea ice / Re: The 2016/2017 freezing season
« on: December 15, 2016, 01:42:43 AM »
Ice Shieldz

 According to this forecast. there's an amazing procession of warm wet storms in the next week up the Greenland coast thru Fram strait and across the Arctic basin, some with a pretty low central pressure  .All constantly disrupting an area of near normal temperatures between the New Siberian Islands and the CAA

Lots of precipitation, Svalbard may get a couple of rainy periods, maybe Franz Josef Land too. And then there's the Pacific side

http://cci-reanalyzer.org/wxrmaps/#GFS-025deg.ARC-LEA.PRCP-WS10

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