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Messages - slow wing

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101
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 19, 2016, 11:55:46 AM »
No more strong Arctic storms in the forecast horizon for the coming week, and a high pressure system settling in in the central Arctic Basin.

Temperatures there should drop. Will the DMI temperature graph drop down as far as the baseline, this month? Before the end of 2016?

102
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 14, 2016, 10:55:37 PM »
bbr,

  Yes, the high, and rising, average surface air temperature above 80N is unprecedented for the date in the DMI record, going at least as far back as 1958, as Terry has checked & posted on another thread.

  This is as I predicted yesterday in comment #671 above.

  It is caused by the strong low pressure currently at 954 hPa that is entering the Arctic Basin through the Fram Strait and is additionally opposed by high pressures above 1040 hPa over Siberia - see first graphic below.

  This dipole setup across the Atlantic side of the Arctic is sweeping warmer (and presumably moisture laden) strong winds into the Arctic basin - see the nullschool graphic below. The point marked by the small green circle, North of Svalbard, registers 64 km/h winds at +0.4oC.


  The current air pressure configuration, at its current strength, is probably also unprecedented in the records for the Arctic at this time of year, given the unprecedented DMI temperature value.

103
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 14, 2016, 04:12:59 AM »
Yep, fantastic work, A-team and the others working on this - really helps to understand what is going on.


  In the short term, yet another strong storm is predicted to be entering the Arctic Basin through the Fram Strait around tomorrow, with a central pressure bottoming out in the 950s in hPa - see attached graphics.

This will bring waves and strong, warmer, moist winds into the Arctic Basin from the Atlantic side.

For those watching the graph of average surface air temperature north of 80N, that should bump the temperature value up even further above the temperature baseline for this time of year. 

104
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 07, 2016, 11:54:49 PM »
A strong low pressure system is currently entering the Arctic Basin through the Fram Strait.

GFS predicts it to bottom out in about 12 hours at around 966 hPa.

How much of an effect will this have on current and future sea ice formation on the Atlantic side?

Waves disrupting ice formation?
Waves and Ekman pumping mixing in warmer, saltier water from the Atlantic near the ice edge?

I don't feel I can quantify these effects even at a level to determine whether they are significant.

Usual gut feeling is the Winter is long and cold and tends to wash out any potential effects on next year's melt season of the weather at this time of year.

105
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 02, 2016, 10:52:49 PM »
That DMI graph is only for >80 degrees N, that is, a 10-degree circle around the North Pole.

The temperature bumps in the graph come from weather patterns that are easily identified from looking at nullschool:
https://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=-35.44,93.43,1444

The current bump is due to warmer southerly winds heading into the 10-degree circle from Svalbard and through the Fram Strait. The nullschool screenshot has has already been posted above at #482
http://forum.arctic-sea-ice.net/index.php/topic,1611.msg92869.html#msg92869

Nullschool also displays the current temperatures in, e.g., the Beaufort-, Chukchi and ESS seas.

106
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 02, 2016, 07:16:06 AM »
Agree, Tigertown, that it is vitally important to deploy more buoys &/or robot divers to better characterise the air, ice, snow and water parameters throughout the Arctic Basin.


This topic has been discussed in some detail on the "What the Buoys are Telling" thread, beginning with http://forum.arctic-sea-ice.net/index.php/topic,327.msg90613.html#msg90613 (#1184).

See, in particular,
http://forum.arctic-sea-ice.net/index.php/topic,327.msg90678.html#msg90678 (#1194 - on the Argo program you refer to).


Yes, a large-scale program such as this should definitely be implemented by next year's melt season!

Is there anyone on here who can assist in making this happen?  :)

Anyone in the Argo collaboration who knows of Argo's Arctic plans? Can push for more monitoring there?

107
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 02, 2016, 04:14:57 AM »
From Neven's comparison page, https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic1101, this year has a lot more blue water on the Pacific side of the Arctic Basin than on any other 01 November in the satellite record:

108
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 01, 2016, 09:38:10 AM »
Agree, jdallen.

Another factor - as pointed out by A-Team in his terrific post - is the cloud cover minimizes the radiative heat loss from the ocean surface into space, which would presumably otherwise be the dominant heat loss mechanism at this time of year.

  On the Pacific side of the Arctic basin, that weather pattern is forecast to continue at least for the next few days, though with weakening winds.

  On the Atlantic side, the forecast is for the high pressure system that is currently on the Arctic side of Greenland to drift southwards. I'm guessing that will bring clear skies to help cool the water near the ice pack edge and so allow the ice pack to expand somewhat more quickly on the Atlantic side. There are lots of unknowns though - at least to me - in the relative importance of the various heat flows and reservoirs - and there appears to be a lot more heat this year than usual in the surface water near the Atlantic sea ice edge - so we will see what happens.

109
Arctic sea ice / Re: The 2016/2017 freezing season
« on: October 29, 2016, 10:05:53 PM »
The building storm is pulling lots of warm moist air into the Arctic basin.

With long reaches of ~60 km/h winds, there will be some waves as well.

Current NullSchool...

110
Arctic sea ice / Re: The 2016/2017 freezing season
« on: October 27, 2016, 09:56:20 AM »
Right now, every time any cold air builds up in the Arctic, it leaks out to lower latitudes and warmer air replaces it. I am not sure this will not continue all winter. It is a hard situation to reverse.

Is what you are referring to basically just a continuation of the extraordinary storminess of the Arctic this year relative to any other year in the satellite record?


Attached is the tropicaltidbits.com ECMWF 72h forecast, which is for 957 hPa at the edge of the ESS opposing 1043 hPa in front of Greenland - which would give an 86 hPa swing across the Arctic basin.

Concerning the other models, the GFS 78h prediction is only somewhat less aggressive: 1040 hPa - 966 hPa = 74 hPa swing; the most aggressive, CMC GEM at both 66h and 72h gives 87 hPa; JMA at 96h gives 72 hPa; while the least aggressive, NAVGEM at 90h gives 65 hPa.

So the general guidance from all the models is for very strong winds across the Arctic basin in the next few days.

111
Arctic sea ice / Re: The 2016/2017 freezing season
« on: October 02, 2016, 02:38:46 AM »
Agree, thanks A-Team. Also very interesting about the Atlantic water.

As background, there is an introduction on that topic on the Wikipedia page, which is very well done:
https://en.wikipedia.org/wiki/Arctic_Ocean

A screen shot of the start of that section is appended:

112
Arctic sea ice / Re: What the Buoys are telling
« on: September 27, 2016, 01:34:50 AM »
  An important point I missed is, for buoys that can be dumped in water then frozen in place,  icebreakers could deploy such buoys all over the Arctic and in all seasons simply by throwing them overboard in the cleared path in the ice behind the ice breaker.

In more detail, for deploying a large number of buoys in a single run then the buoys could instead be deployed from a freighter following an icebreaker. This gets around any potential issues of limited storage space in an icebreaker.

So rapid deployment of a grid of such buoys over the entire Arctic Basin should be doable.

113
Arctic sea ice / Re: What the Buoys are telling
« on: September 26, 2016, 11:54:28 PM »
Yes, these are good ideas!

  As a valuable complement to the array of surface buoys, presumably the existing Argo drifter-buoys/program could be encouraged to extend into at least some of the ice-free parts of the Arctic during the  melt season. Argo is the main source of information on current, temperature and salinity profiles in the world's oceans but the graphic doesn't appear to show any deployed in the Arctic Basin.

http://www.argo.ucsd.edu/
https://en.wikipedia.org/wiki/Argo_(oceanography)


This .pdf flyer - http://www.argo.ucsd.edu/Argoflyer_final.pdf - which appears to be from 2003, gives a cost of $15,000 per drifter and $20-25M/year to deploy 825 floats/year. That's broadly similar to the costs assumed above.

114
Arctic sea ice / Re: What the Buoys are telling
« on: September 26, 2016, 03:03:46 PM »
Thanks for the links Jim. I can't see a cost there but a bulk deployment makes a lot of sense to me.

The reports from the scientists deploying these things seem to indicate it can take a few days to find an appropriate floe to drill through and place a buoy, and a day or so to set it up and calibrate it. 10 per day doesn't look feasible to me. Think also about how much cargo space each requires, and how many you can actually take with you per trip - the sheer physical logistics of deployment.
As I suggested, the first issue can be avoided if (at least most of) the buoys are dumped in the water near the end of the melt season and the ice allowed to freeze around them. Deploying an average of 10 per day in this way should be doable.

  The buoys can be shipped to the Arctic by container ship. A 40' shipping container is either 66 or 78 m^3 (web search returns both numbers) so, depending on the size, each one should hold some tens of buoys ready for deployment. Let's assume 40 buoys per container, so 1000 buoys would require 25 containers. Then that would require picking up and deploying one container worth of buoys every 4 days.

  I suspect that a lot of vessels would be available for hire that could deploy them over much of the Arctic Basin during the melt season - it need not require a full ice breaker and could be more than one vessel. Such vessels also could transport the buoys to the ice breaker for deployment from that.

So the numbers still seem reasonable when written out on the back of an envelope. It's probably worth fleshing it out a bit more to see whether there is a show stopper or not.

115
Arctic sea ice / Re: What the Buoys are telling
« on: September 26, 2016, 01:29:02 PM »
http://www.chrispolashenski.com/docs/a57a149.pdf
Paper from 2011 - the production cost current buoys is $35,000 dollars.

http://www.epic.noaa.gov/SEARCH/obs/workshop/reports/rigor.pdf
Report from a few years ago pointing out that the deployment costs are far higher than the buoy costs.

https://www.nsf.gov/about/congress/109/alb_icebreaker_092606.jsp
Testimony to Congress pointing out that the operating costs for an Arctic mission with icebreaker support are in the regions of $20-$30,000 per day.
Thanks Peter, that is very helpful.

That's actually in the ballpark of what I thought. Quite reasonable that $35,000/buoy would drop to $10,000/buoy for bulk production of 1000 buoys. Deployment over 100 days with those operating costs would then be $2-3 million.

The red text is important. The deployment costs will almost be fixed - presumably increasing only slowly with the number of buoys deployed as they will anyway cover about the same area of ocean. It's highly non-optimal then to spend only a small fraction of the budget on the buoys themselves - better to spend ~50% on buoys to allow deployment of a large number of them.

That is good value for the importance of the science. It should be done!  :)

116
Arctic sea ice / Re: What the Buoys are telling
« on: September 26, 2016, 11:11:39 AM »
I'll just guess while wait for someone knowledgeable...  :P

For say $20 million, could 1000 bouys with temperature sensors, salinity measurement, maybe currents vs. depth, and even webcams  :) be deployed towards the end of the melt season - where most could just be dropped down on the Arctic ocean by a ship?

That would be e.g. $10,000/bouy + $10 million extra costs.

If so then that would be a relative bargain in my opinion given the importance of the science.

117
Arctic sea ice / Re: What the Buoys are telling
« on: September 26, 2016, 10:00:27 AM »
Trying to guess what is going on with salinity as well as heat at the start of the freezing season and these instrumented buoys really are invaluable but it is obvious there are too few of them to get a good picture.

Presumably this is limited by funding? What is the outlook there? This is important science. Could someone give a ballpark estimate on how much it would cost to deploy 100/year? 1000/year?


118
Arctic sea ice / Re: The 2016/2017 freezing season
« on: September 25, 2016, 12:53:06 PM »
Very informative plots, thanks A-Team! The re-freeze is impressive.

... There must have been hellacious winds to have blown so much ice eastward in the CAA channels and lower CAB, the effect extends over thousands of km.
  It's much too fast for wind-blown ice, which will typically travel at 5-10% of the wind speed.

  Instead, the water near to the ice is seen to be more susceptible to freeze-over. Speculating on some potential reasons:
  - fresher water, as is where ice has recently melted (& maybe with some residual ice still there)?
  - less windy near the ice?
  - colder water &/or air near the ice?

From the travels of O buoy 14 we know that it has been transported from the open ocean into the strait over the last month.  Started off in open water and then met up with the ice and was swept into the strait with it.
Yep, thanks for this and sorry, A-Team, I may have been posting at cross-purposes to you. When you talked about blowing ice "eastward" and for thousands of km I thought you were referring to the re-freeze heading in the direction of Siberia. On re-reading, it appears you were instead talking about eastward within the CAA channels.

 Yes, it's true the winds this melt season have been extraordinary - indeed unprecedented in the record if I'm not mistaken.

119
Arctic sea ice / Re: The 2016/2017 freezing season
« on: September 25, 2016, 03:16:50 AM »
Very informative plots, thanks A-Team! The re-freeze is impressive.

... There must have been hellacious winds to have blown so much ice eastward in the CAA channels and lower CAB, the effect extends over thousands of km.
  It's much too fast for wind-blown ice, which will typically travel at 5-10% of the wind speed.

  Instead, the water near to the ice is seen to be more susceptible to freeze-over. Speculating on some potential reasons:
  - fresher water, as is where ice has recently melted (& maybe with some residual ice still there)?
  - less windy near the ice?
  - colder water &/or air near the ice?

120
Arctic sea ice / Re: Latest PIOMAS update (September)
« on: September 25, 2016, 02:53:57 AM »
Thank you Michael, appreciated!

121
Arctic sea ice / Re: The 2016/2017 freezing season
« on: September 24, 2016, 12:37:10 PM »
  That's a very good question on snow cover. If it insulates the ice this early then surely the dominant effect would be to minimise thickening during the freeze season? That would be bad for the 2017 melt season.

  The storms keep on rolling in. As shown below, there are currently 4 storm centres in the Arctic Basin, with the strongest having a low pressure of ~983 hPa. Yet another storm with a similar minimum pressure is predicted to arrive in around 4 days time.


  Two lines of questions for those who have watched the Arctic weather more closely than I during past freeze seasons:

1) is it normal to have as many storms, one after the other, during the beginning of the freeze season? If not, how unprecedented is the current situation; and

2) what are the likely effects and the likely consequences for the rest of the freeze season and the 2017 melt season? For example. would they be expected to dump a lot of snow on the ice? How significantly would they be mixing up the halocline and adding salt to the surface? Are they at least partly responsible for the quick initial freeze-over this year?

122
Arctic sea ice / Re: Slater's thread
« on: September 20, 2016, 11:00:36 AM »
That is very sad.

Here is the link to Neven's blog post:
http://neven1.typepad.com/blog/2016/09/in-memoriam-andrew-slater.html.

I only knew of him from his forecast page:
http://cires1.colorado.edu/~aslater/SEAICE/

I'll record now that his methodology there really impressed me. Dr Slater looked at each bit of Arctic sea ice in turn over the Arctic and predicted its survival probability. That approach makes a lot of sense to me.

He had already developed quite a good model to do that and presumably had progressive improvements in mind to make it even better.

Sad news. RIP Andrew Slater.

123
Arctic sea ice / Re: The 2016 melting season
« on: September 19, 2016, 03:15:06 AM »
Agreed, jdallen. Sadly.


I hope the cabin can float !
I took it that the cabin and the bear are on a boat.  :o :-[ :'(

124
Arctic sea ice / Re: The 2016 melting season
« on: September 18, 2016, 11:44:12 PM »
Thanks A-Team, those superb graphics really help our understanding.


You point out the striking export of ice to the Canadian Arctic Archipelago (CAA). What is so scary about that is that the CAA is becoming a sink rather than a sanctuary for the multi-year Arctic sea ice.

The ice that goes in there is probably not coming back out into the Arctic Basin. Instead, though, it can spread out through the various channels of the CAA and, increasingly, the CAA is melting out every melt season.

Until the most recent seasons, the Fram Strait has been the traditional 'graveyard' for the multi-year ice: ice that passes through there is doomed by the warmer Atlantic water and air.

You show the Nares Strait is exporting like crazy as well - as it presumably has also done  in previous years. The Nares is so much narrower than the Fram though that it cannot deal to nearly as much ice.

  This melt season however, the Fram Strait (and the smaller Nares) has been just one of several sinks for the ice. The whole Atlantic front of the ice pack was melting out before it reached Svalbard and the string of islands alongside it (=the boundary to the Barents sea?). On the other side, the Beaufort Sea opened up so early as to become effectively another graveyard for the ice pack. (While the Siberian side opened up also - the prevailing winds, away from Siberia, didn't push as much ice in that direction.) And now the CAA is added as a sink on the Western side, that is, exactly where the prevailing winds tend to push the ice pack.

125
Arctic sea ice / Re: The 2016 melting season
« on: September 16, 2016, 08:05:40 AM »
Hey, where's everyone gone from this thread?!  :P

Espen is reporting a 16,000 km^2 drop in IJIS extent, now only about 136,000 km^2 above the putative minimum from 7 September.

Also, a strong storm is currently raging in the Arctic basin. GFS at Tropicaltidbits.com has it currently at 977 hPa and forecasts it to stay there and on or below 985 hPa for a whole week from now!


Could it... ? Would it... ? Is it possible... ?  :)

126
Arctic sea ice / Re: The 2016 melting season
« on: September 16, 2016, 04:37:46 AM »
Attached below is the Arctic ice age in March 2016 - it's a screenshot from a gif posted a page or two back by A-Team.

  Does A-Team or anyone else know how much of the older ice survived the melt season?

  Can any of the features at the end of the melt season be matched to regions of older ice in the March map? The 'Wrangel arm' is an obvious example.

  (Even better would be if, by some luck, someone had done the ice age map for the end of the melt  season, or even an animation for the ice age extending through the melt season. A-Team, do you happen to know if anyone might have done/will do that?)

  The old ice in the Beaufort Sea, for example, didn't survive. Did 2016 then reach a record low of multi-year ice?


127
Arctic sea ice / Re: The 2016/2017 freezing season
« on: September 15, 2016, 02:16:58 AM »
Yes, it's a strong storm and an interesting question whether it could potentially reverse at least some of the refreeze.

Currently near the North Pole and at 988 hPa, GFS at Tropicaltidbits predicts it to bottom out in around 36 hours, at 976 hPa, and to endure for about a week at below 990 hPa, located in the Arctic Basin and mainly off the Canadian Arctic coast.

What will that do to the newly formed refreeze ice?  :-\

128
Arctic sea ice / Re: The 2016 melting season
« on: September 14, 2016, 04:14:10 AM »
The fast refreeze continues. Attached below is the progression from 7 to 13 August 2016 as shown by the U. Bremen's Arctic sea ice concentration maps using AMSR2 satellite data.

As well as adding the latest of those maps, from 13 August, the 7 August map was added to the beginning of the sequence as that was the date of the extent minimum as determined by NSIDC:
The NSIDC northern hemisphere sea ice extent minimum was September 7th, 2016 with a value of 4.083*10^6 KM^2.

129
Arctic sea ice / Re: The 2016 melting season
« on: September 13, 2016, 04:03:11 AM »
  U. Bremen has just updated its Arctic sea ice concentration map and the animation below now spans from 8 to 12 September 2016.

  Today's update shows another consecutive day of big gains in ice area and extent. In the absence of some extraordinary weather then that confirms the minima in area and extent have already passed for the 2016 melt season.

  Of sentimental interest only, the last remnants of Big Block disappeared today!

130
Arctic sea ice / Re: The 2016 melting season
« on: September 12, 2016, 05:55:21 AM »
The gif below loops through U. Bremen's Arctic sea ice concentration maps for 8-11 September.

  The Eastern (Siberian) side is still losing ice area: the Wrangel arm continues to atrophy and ice around the Laptev Sea is also disappearing.

  However, this is being outpaced by the ice envelope growing outwards from the Canadian Arctic coast and the ice concentration is also growing at latitudes above 85oN, giving overall net gains in area and extent.

So it looks like the 2016 minimum is now behind us for extent and area (though the volume minimum may well be later).

131
Arctic sea ice / Re: The 2016 melting season
« on: September 11, 2016, 04:56:59 AM »
The U. Bremen sea ice map is showing a second consecutive day of significant refreeze in the Arctic.

ORIGINAL: With the current weather pattern expected to persist for at least the next couple of days, a reversal is presumably unlikely and the refreeze will take hold.

EDIT: should add a big caveat. On taking a closer look, Nullschool is showing strong winds now in key refreeze areas of the past two days. See attachments 2 to 4, showing the winds & temperatures at 'points of interest' 1 and 2 - with particularly strong winds at point 1, which is close to the centre of a low pressure system.

Is the refreeze stable in such strong winds and with temperatures at only around -3oC? I wouldn't have thought so. Also, some of the ice appearing around points 1 and 2 is likely to be from the wind pushing around existing ice, rather than new ice. So perhaps best if I leave it with the observed &/or reconstructed data shown in the figures below and 'wait and see' what happens.   :) 

132
Arctic sea ice / Re: The 2016 melting season
« on: September 08, 2016, 01:59:09 PM »
  The Terra satellite images show that the ice around the North Pole is pretty much rubble at the moment.

  The ice is still closely packed right at the Pole but degenerates with distance to regions with gaps of open water between individual floes, progressively and on a distance scale of about 50 km when looking to the Eastern side of the North Pole.

133
Arctic sea ice / Re: The 2016 melting season
« on: September 08, 2016, 04:34:08 AM »
As attached below, today is another opportunity to check Neven's year-to-year comparison of U. Bremen sea ice concentration maps:
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0907.

Today's map still resembles the one for 2010, only with the ice distribution on the East side skewed more towards the Atlantic.

How will the melt season end this year? The 'reverse dipole' weather configuration has settled in and is forecast to remain for several days yet - with low atmospheric pressure off the Canadian Arctic coast opposing high  pressure on the Siberian side.

As shown by the Nullschool map below, the Siberian side of the Arctic Basin remains breezy and quite warm for the date - above zero degrees C near the coast dropping away to slightly below zero further into the ocean. That trend also extends westwards to the Beaufort Sea off the Alaskan coast.

It appears then that what remains of the 'Wrangel Arm' of sea ice is still in peril of melting right out, or nearly so.

Further West, in the Beaufort Sea, it looks likely we will lose the remnants of the storied Big Block.


The American side is cooler and less windy, dropping down to below -10oC near the centre (I presume) of the low pressure. With little wind there as well, might that begin to freeze over?


As always for me, the wild card is the anomalously high amount of first year ice left in and around the Barents Sea. I doubt there is time for much fractional change here before freeze-over, but meanwhile will it grow slightly or shrink slightly? No idea.

And that carries over to whether we will have early or late minima in overall ice extent and area. No idea on that as well.

134
Arctic sea ice / Re: The 2016 melting season
« on: September 07, 2016, 11:02:54 PM »
For those who have time. Go to  www.polarview.aq/sic/arctic/

Click on the 1st of the month while zoomed on the NE corner of Greenland.
Click the animate button. You have to click 1st again and animate again to repeat.
...
Thanks!

That's a lovely animation, very informative. This melt season we have been spoiled with some of the new graphic displays coming out - thanks to those involved. And that is not even to mention the terrific visual aids from some of those on this forum, e.g. A-team & Wipneus etc.

135
Arctic sea ice / Re: Stupid Questions :o
« on: September 07, 2016, 08:25:41 AM »
My stupid question, for the meteorologists:
At this time of year - i.e. near the end of the melt season - is a high pressure system in the Arctic basin helpful or hurtful for the area beneath it to freeze over?

On the one hand, the air near ground level might be a little warmer, as high pressure warms the air due to adiabatic compression.

On the other hand, the skies are more likely to be cloudless. At this time of year I might expect the sky to appear cold and a sink for thermal radiation.

So what is the actual situation?  ???

136
Arctic sea ice / Re: Stupid Questions :o
« on: September 07, 2016, 08:15:31 AM »
It is possible in nullschool to check how the wind was 24 hours or 48 hours ago? How can I do it?
Yes.
1) Click on "earth"
2) at the "Control" line, click on "<<": once for 24h, twice for 48h.

137
Arctic sea ice / Re: 2016 sea ice area and extent data
« on: September 06, 2016, 06:25:26 AM »
The CAA is like a vacuum cleaner!  The last time there was virtually no 100% concentration pack ice against the CAA was...?  (Answers rounded to the nearest million years will be accepted!)
It occasionally loses suction...

138
Arctic sea ice / Re: The 2016 melting season
« on: September 06, 2016, 05:36:14 AM »
Really appreciating the graphics and animations available to us this melt season.


As attached, the crimson high-concentration regions have moved around a lot from yesterday in today's U. Bremen Arctic sea ice concentration map - as Lodger pointed out happens in general.

In particular, some of the lower concentration area near the North Pole has moved away from there - towards Alaska as well as the Canadian Arctic coastline - showing the track of the strong low pressure centre that is now parked against that coastline - see second attachment, where the low pressure system is recorded as at 987 hPa.

The reverse dipole configuration is evident, with a 1030 hPa high on the Siberian side of the Arctic Basin, across from that low pressure system. That will cause winds to blow from the Atlantic side of the Basin through towards Alaska. That configuration is forecast to persist for at least the next several days and so may dominate the ice dynamics until freeze-over.

  The low is sitting right on the ice sanctuary up against the Canadian Arctic coast and might be expected to have more effect on that ice than the more distant high will. So that ice - which appears to be pretty much rubble with little mechanical resistance to dispersion - might be expected to spread out away from the low pressure centre, as is usual for lows in the Arctic.

  So will this cause an uptick in Arctic sea ice extent? Perhaps leading to an early minimum in that parameter?

  Meanwhile, the amount (volume) of the ice might continue to go down as the ice moves around and expands back into the Beaufort Sea. So we might end up with a low final volume - perhaps even challenging the 2012 record value for PIOMAS volume?

The interesting melt season continues!








139
Arctic sea ice / Re: The 2016 melting season
« on: September 05, 2016, 04:06:26 AM »
A reasonably dramatic Arctic sea ice concentration map today from University of Bremen: the purple-coloured 'ice sanctuary' of closely packed ice off the Canadian Arctic coast can no longer be said to extend to the North Pole.

  That's only going to get more stark over the coming days as the winds generated by the 'reverse dipole' atmospheric setup (low pressure at the Canadian Arctic coast combined with high pressure on the Russian side of the Arctic Basin) shove the edge of the high concentration 'sanctuary ice pack' further away from the North Pole and in the direction of Alaska.

140
Arctic sea ice / Re: What the Buoys are telling
« on: September 04, 2016, 02:20:27 AM »
Maybe some clouds or fog back-lit by the sun?

The shadows in the waves shows the camera is facing somewhat towards the sun.

141
Arctic sea ice / Re: Latest PIOMAS update (September)
« on: September 03, 2016, 11:53:25 AM »
Thanks, Wipneus!

Maybe a final, final post showing the ice at the last day of the month?  :P


Best of luck with your move.  :)


EDIT: here's the screenshot anyway if Wipneus is already lost inside a packing crate...

142
Arctic sea ice / Re: The 2016 melting season
« on: September 03, 2016, 02:43:56 AM »
EDIT: very interesting, Artful Dodger! The procession of powerful cyclones through the Arctic Basin has certainly been a striking feature of this melt season. The trend looks set to continue over the rest of this melt season, as follows.

 There's a strong low pressure system sitting currently about halfway between Svalbard and the North Pole, with a minimum pressure of 981 hPa according to the GFS run at tropicaltidbits.com
http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=z500_mslp&runtime=2016090218&fh=6&xpos=0&ypos=155.

 As appended, Nullschool shows it generating winds reaching 50 km/h in the Atlantic-side rubble sea ice.

 There's another low in the Arctic Basin, much weaker and further over towards Alaska, as well as a high pressure system just inside the Bering Strait and near Wrangel Island.

 What's notable in the GFS forecast - extending over 17 days, and more-or-less confirmed by the ECMWF forecast over the first 11 days - is the forecast dominance of low pressure in the Arctic Basin over the foreseeable future. Of those 17 days, the lowest forecast pressure in the Arctic Basin is in the:
990s hPa for 5 of 17 days
980s hPa for 11 of 17 days
970s hPa for 1 of 17 days (973 hPa way out on 18 September).

 That low pressure dominance is underpinned by the Arctic Basin showing a persistent pressure minimum at the 500 hPa height - displayed as deep blues and purples in the tropicaltidbits.com weather charts.

 So perhaps the Arctic Basin is going to remain windy and dominated by low pressure over the final weeks and days of the melt season?

143
Arctic sea ice / Re: The 2016 melting season
« on: September 02, 2016, 01:39:35 PM »
  As attached, 1 September is another one of the dates used for Neven's excellent side-by-side comparison of U. Bremen's Arctic sea ice concentration maps for the different years:
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0901.

  By now, this year looks much more ragged than in any previous year, including the record-breaking 2012.

 The high-concentration band of ice off the Canadian Arctic coast in 2016 probably resembles most closely to that in 2010. However, compared to 2010 much less remains of the lower concentration ice on the Atlantic and Russian sides and what does remain is now mostly in or around the Barents Sea.

At least another week of high winds over the Arctic Basin to deteriorate the ice pack further before it heads into re-freeze?

144
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 02, 2016, 03:00:07 AM »
 ;D

How big is that circle with the polar bears in it?

145
Arctic sea ice / Re: The 2016 melting season
« on: September 01, 2016, 12:11:13 PM »
The TERRA satellite got a peek through the clouds to show rubble with polynyas currently reaching to about 10 km from the North Pole..

146
Arctic sea ice / Re: The 2016 melting season
« on: August 31, 2016, 04:00:16 PM »
Here is a simulated melt scenario -- not a prediction, just a scenario -- of what it would take in coming weeks to reduce the residual ice cover to 2.4 million km2.

Thanks for this, above at #4452, and other very interesting animations.

It would be shocking if the ice reached that scenario this year - it looks well below the 2012 minimum. Just wanted to check that the remaining area (or is it extent??) in that scenario is as much as 2.4 million km2.

Surprisingly to me, that is above the actual Cryosphere Today minimum Arctic sea ice area for any day in 2012, which was 2.234 million km2, even though that scenario looks like less ice to me. (Is this an issue of extent vs. area?)

As another comparison though, the area inside 10 degrees from the Pole is about 4 million km2
~ pi * (10,000/9) km2 within the approximations that 90 degrees ~10,000 km & approximating as a 2-dimensional disk.

What remains looks by eye to be less than half of that area as it appears the ice wouldn't fill half the region above.

So is it the approximation or else just my eyes fooling me?

147
Arctic sea ice / Re: The 2016 melting season
« on: August 31, 2016, 01:36:14 PM »
As appended, the Suomi satellite didn't quite get a clear view of the North Pole. However, on peering through the thin clouds though, polynyas can be seen from about 20 km above the Pole - i.e. on the Russian side - and filling a progressively larger fraction on travelling further from the Pole in that direction.

  As also appended, moderately strong winds are currently blowing from the general direction of the polynya (although shifting within a day to a direction more from the Atlantic side) so maybe one or more polynya will sweep over the North Pole within a day or so?

  Beyond that, we may end up with rubble over the North Pole within the coming week or two, as Jim Hunt illustrated above has already happened back in 2013.

  As a speculative potential difference to 2013 though, we may still possibly get rubble this year extending all the way from the North Pole to the open ocean - if it happened this year then that would be indicative of the dire straits the Arctic is in already. (Or it could get even worse, the way the ice is deteriorating this year, with a 'rubble passage' going right through the central Arctic Basin, and including the North Pole. We already aren't far off that, with just a little bit more ice to lose near the ends before the current rubble region could be said to extend from the Atlantic side all the way through to the Siberian Sea Bite.)



148
Arctic sea ice / Re: The 2016 melting season
« on: August 30, 2016, 01:18:25 AM »
A low pressure system is currently parked right next to the Severnaya Zemlya islands, so the Laptev arm of the sea ice is getting hit with warm winds up to 50 km/h and maybe some waves.

Will this be its final test before surviving to freeze-over?

149
Arctic sea ice / Re: The 2016 melting season
« on: August 29, 2016, 02:56:25 PM »
Attached are a couple more NASA EOSDIS Worldview satellite pictures, true colour view from the Terra Satellite for today, 29 August 2016:
 1) The Russian side of the Arctic; and
 2) zoom-in to the remaining ice in and around the Laptev Sea.

For the second image, the ice on the left hand side might well be brash ice. However, the rest looks like a rubble of floes ~1-10 km across - getting progressively denser in packing fraction from left to right - that might well survive the melt season.

It will be interesting to see whether or not the forecast strong winds in that region over the next few days can wipe out any of that rubble.

150
Arctic sea ice / Re: The 2016 melting season
« on: August 29, 2016, 11:40:14 AM »
An impressive pressure difference of 64 hPa across the Arctic Basin occurred at 00z on 29 August 2016. Attached is the ECMWF pressure map showing a 975 hPa low north of Svalbard opposed by a 1039 high just inside the Bering Strait.

Is that a record pressure difference observed inside the Arctic Basin during the melt season? Probably could only have been exceeded earlier this season or else during the GAC 2012.

Also attached is the Nullschool wind and temperature map for today showing the strong wind field produced by that set-up, with winds blowing from the Siberian side to the Canadian side over almost all of the Arctic Basin.

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