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Messages - slow wing

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1
Arctic sea ice / Re: The 2017 melting season
« on: March 26, 2017, 03:09:27 AM »
Terrific, Hyperion!

Yes, start a thread please.

The greatest of respect to the many dedicated scientists, technicians etc. who are already providing the experimental information we rely on to understand the state of the Arctic.

Having said that, it's a disgrace that we don't have more coverage; a disgrace that we need inadequately calibrated models for the currents, water temperatures and salinities, etc - as well as information on the ice and snow state and thickness.

   Smart probes for the Arctic are difficult to fund even while smart bombs are streaming off the assembly lines.

   More broadly than your particular solution, it makes a lot of sense to have a thread on the future experimental program for monitoring the Arctic.

   Better in"Policy and solutions" or in "Science"?

   I had a look previously and couldn't find an existing thread. (Did I just miss it?)

   So there were a series of posts in the "What the Buoys are telling" thread kicking off with this one from me and then with those more knowledgeable and experienced posting valuable content.

Maybe all that can be moved to a new dedicated thread for e.g. "Existing and proposed experimental apparatus and programs for the Arctic" and add your stuff and other proposed solutions?

2
Arctic sea ice / Re: The 2017 melting season
« on: March 24, 2017, 12:50:07 AM »
"...the Arctic turns into a single gyre"?

 There hasn't even been a gyre lately. Instead the ice in the Arctic Basin has been blown from the Russian side and compressed against the Canadian side, with some leaking out towards the Atlantic...




  The good news is that the compression has helped to heal the Beaufort Sea back to around a 2 metre thickness.

   And if the pattern ends soon then there is still well over a month left of weather cold enough to somewhat heal the tears on the Russian side.

   But what if the tear-and-compression continues well into April or May? Will large stretches of water remain open on the Russian side, efficiently absorbing the peak insolation around the Summer solstice?

  A broader question is why so much compression? Is there enough thin and weak ice this year in the Arctic Basin that any wind pressure from the Russian side will always result in movement and compression? And is this movement replacing the Beaufort gyre of seasons past, with the ice now compressing rather than transferring the force for rotation?

   If so, does this mean that maximum Arctic sea ice volume for the year has descended this season to a transition value, or even a tipping point, where the ice will continue to tear-and-compress from the Russian side heading into the Summer melt season, with the Russian side therefore opening up anomalously early?

   Or, instead, will the movement damp down within a few weeks and those consequences won't come to pass this year?

   Either way, the plot twists and turns of the melt season are going to provide us with riveting viewing.

3
Arctic sea ice / Re: Arctic Image of the Day
« on: March 20, 2017, 10:16:59 PM »
It's Icepacman!  :o

4
Arctic sea ice / Re: The 2017 melting season
« on: March 14, 2017, 08:42:52 PM »
Thanks Romett1. Yes, the HYCOM prediction is scary, with a lot of thicker ice either exiting through the Fram Strait or else heading in that direction.

  A lot of the thickening in the Beaufort Sea appears to be from compression, with the ice blown towards the Alaskan and Canadian Arctic coastlines.

  It's going to be critical how much new ice grows over the next month on the Siberian side to replace the ice that has migrated West. Are we going to have much of the thin ice on the Atlantic side of the Laptev Sea melted out and exposed to peak insolation by around the Summer solstice?

5
Arctic sea ice / Re: Stupid Questions :o
« on: March 14, 2017, 04:41:55 AM »
OK, that's a different statement. Note however that last year, 2016, didn't top out early and last year also had anomalously high 80N+ temperatures at this time of year.

At the beginning of March this year was about 2K km^3 below 2016 - which topped out as the record min-max (~tied with 2011) - so, yes, it wouldn't be too surprising if we ended up around 2K km^3 below that.

6
Arctic sea ice / Re: Stupid Questions :o
« on: March 14, 2017, 03:14:43 AM »
This is as much ice as we are going to get.

Based on what? It's only mid-March. According to PIOMAS, ice volume typically grows into mid-April - so another month or so.


7
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2017, 01:10:42 AM »
Terrific information, thanks Andreas! Your reply, #1387 above, beautifully addressed my question on how much insolation the Arctic actually receives.

What a great forum this is!

8
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 04, 2017, 10:46:35 PM »
I'm still uncertain on how much insolation the Arctic actually gets.

Is the plot showing insolation on a horizontal surface? Or on a tracking surface always perpendicular to the sun? (I presume the former.)


More importantly, does it include a model or measurement of the effects of the atmosphere, including the variable moisture content and cloud cover? If it's insolation at the top of the atmosphere then that's much larger than what reaches the ground. That is particularly true in the Arctic, given the typically low solar elevations from the horizon.

  The Arctic was cloudier than usual last summer, so the insolation reaching the ground would also have been less than usual. Will this summer be similar?


So the question of how much insolation reaches the Arctic is not simple and is not fully addressed by a single graph.

9
Arctic sea ice / Re: Poll: 2017 PIOMAS Maximum Monthly Figure
« on: March 04, 2017, 10:27:46 AM »
Voted 20.5-21.0 x 10^3 km^3.


At day 59 we were at 18.6 in those units.

Archimid posted on the PIOMAS update thread that, in past years, the average gain to maximum from there has been 2.1. Taking the average gives 18.6 + 2.1 = 20.7 - hence the choice of bin.


It could be argued that the Arctic Basin hasn't been as cold as usual this year, with FDDs way down. That trend may well continue over the next month or two.

On the other hand, I see lots of potential for adding volume in the 'ice factory' on the Russian side of the Arctic Basin. Offshore winds there have been, and still are, exposing new sea surface there which is rapidly freezing over and thickening.

So I think taking the average gain from day 59 to maximum ice volume is reasonable.







10
Developers Corner / Re: Mapping GeoCoded Data Sets
« on: February 26, 2017, 11:58:06 PM »
Hi CognitiveBias

   Yep, that should also be fine. I might have been getting ahead of myself thinking about a problem that doesn't matter - your option of using Sept 1 everywhere is simpler and it would be great to get a first look at the distributions!

11
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 26, 2017, 11:27:49 PM »
2/2 (needed a second post due to 4 attachment limit)

Continuing with inspecting the Canadian Ice Service (CIS) charts of the 2009 melt season in the West Arctic, which corresponds roughly to the Beaufort Sea as well as some of CAB between the Beaufort and the North Pole. Recall from the posts above that the sea ice in the West Arctic currently (late February) looks worst in the CIS archives and that 2009 looks the second worst.

  It turns out that the first year ice mostly melted out anyway by the end of the 2009 melt season in the West Arctic, but much of the multi-year ice survived.


  So that gives us some idea of what might happen again in the West Arctic this year, in the scenario of similar weather to 2009 over the next several months. Unsurprisingly, the Beaufort Sea will melt right out. But the multi-year ice North of that could survive.


  In the alternative scenario that the stormier weather of 2016-7 persists into the 2017 melt season, then much of the multi-year ice currently in the West Arctic may also be lost, due to transport by the wind into either the CAA 'garlic press' or into a Beaufort Sea 'kill zone' that has already melted out.

Attached: Canadian Ice Service chart for West Arctic on 2009-09-28.

12
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 26, 2017, 11:17:54 AM »
[EDIT: I redid this post as I was dissatisfied with my original characterisation of the 2009 charts]

1/2
Had further look at the archived Canadian Ice Service(CIS) sea ice charts for the Beaufort Sea. Previously, I had only looked back to 2010 whereas the archive goes back to 2004.

It turns out that the 2009 Beaufort ice also looked fairly weak at this time of year - the weakest in the archive outside of this year.  (The years earlier than 2009, however, had considerably more thick ice than this year.)

  As one historical surrogate then for the potential Beaufort sea ice development this melt season, the 2009 progress of the Beaufort ice can be examined for through the end of the freeze season and then for the melt season. On inspection, it turns out the 2009 Beaufort ice continued to thicken until at least mid-March and most survived well into July.

The relevant charts from the CIS archive follow, for dates in this order:
2017-02-20 (repost) - the ice condition this year; note all the light green = 1st year ice <120cm thick
2009-02-16 - note that 2009 also had a lot of light green around mid-February
2009-03-16 - one month later, the light green has ~all gone dark = >120 cm
2009-07-13 - the Beaufort hadn't melted out much by mid-July 2009

13
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 11:32:48 PM »
4/4 It is seen that this year stands out in having the least multi-year ice (brown) in the region and easily the most light green, which is first year ice of 70-120 cm thick - presumably too thin at the moment to stand much chance of surviving the next melt season.

Shared Humanity also has a good point about the CAA now turning into a sink (the 'garlic press', as Neven has coined) rather than a sanctuary for thicker multi-year ice.


So the Beaufort Sea looks in trouble this season.


Concerning a wider view of the Arctic ice, it's helpful to have this region with detailed charts that are presumably reliable. These can be used for assessing and maybe even cross calibrating some of the other ice maps that show the entire Arctic Basin.

14
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 11:22:14 PM »
Some explanation on how to read the charts.

Canadian Ice Service has a detailed explanation in their online Manual of Ice (MANICE), the most relevant page of which is the start of Chapter 3: Observed Ice Charts, at http://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=2CE448E2-1&offset=6&toc=show.

Briefly, the little "Egg Code" number charts are very helpful in giving the concentration, stage of development (e.g. "First stage thin first-year,   30 - 50 centimetres") and form (e.g. "Big floe,   500 - 2,000 metres") of each designated local region of ice.

The most relevant colour coding for us is:
'light olive' = thin first year ice, 30-70 cm thick
light green = medium first year ice, 70-120 cm thick
dark green = thick first year ice, >120 cm thick
brown = older than first year ice.

Here is a map of the Western Arctic region displayed ...



15
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 11:02:36 PM »
Above was the charts closest to 20 February for 2017, 2016, 2015 and 2014; now the same for
2013, 2012, 2011 and 2010...


16
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 10:59:30 PM »
Thanks again, Jim. Canadian Ice Service have a superb website,
http://www.ec.gc.ca/glaces-ice/default.asp?lang=En, with a fine archive facility, retrieving ice charts at:
http://iceweb1.cis.ec.gc.ca/Archive/page1.xhtml?lang=en.

From the options tables, I selected:
Weekly Regional Ice Charts - WMO Colour (2003 - 2017)
Western Arctic Regional
... and saved to zip the weekly charts for around this date for each of the past 8 years (files end in "SD'), as follows (latest to earliest year)...

17
Arctic sea ice / Re: Glossary ... for newbies and others
« on: February 24, 2017, 09:43:09 PM »
Thanks shmengie! I didn't know that and it really works!

18
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 11:29:13 AM »
Thanks Jim, appreciated.

2017, 2016, 2015 and 2014 sea ice in the Beaufort compared by ACNFS for 23 February...

The code version has changed between years, and the colour palette has slightly. But the difference this year is still striking! :o


Now it really would be nice to also check this using the Canadian maps for the Beaufort!

19
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 24, 2017, 06:37:21 AM »
For comparison, it would be great to see ACNFS maps for the same dates in previous years. Are any available? Or that other Canadian sea ice map?

Does either have a map archive on their web page?

I had a quick skim of last year's freezing season thread,
http://forum.arctic-sea-ice.net/index.php/topic,1377.500.html
and couldn't immediately see a corresponding map.

Shouldn't those maps in particular give about the best information available on whether the Beaufort sea ice is in better or worse condition than last year?





As consolation, here's a gif Neven did of the Atlantic side about a year ago, taken from last year's thread. The ice around Svalbard wasn't in good shape then either...
It seems that it is now (almost?) possible to circumnavigate Svalbard. It is a little early for that, isn't it?


Nah, we're not impressed by that one anymore. Circumnavigating Svalbard AND Franz Josef Land, however, is a different cookie:  ;)





20
Arctic sea ice / Re: IJIS
« on: February 15, 2017, 07:21:07 AM »
It appears that the strong upwards trend should continue in the next few days as well.

At least that's how I interpret the 'ARC' prediction map posted by Tigertown in post #2779 on the Freezing thread:
http://forum.arctic-sea-ice.net/index.php/topic,1611.msg103206.html#msg103206.


That should take this year's IJIS extent out of first place, probably beginning tomorrow.

21
Developers Corner / Re: Mapping GeoCoded Data Sets
« on: February 12, 2017, 01:44:42 AM »
Thanks for the interest in a map of FDD and for looking into coding it up. I am looking forward to seeing these plots and - thanks Blizzard for the links - there is an outside chance I might try to learn Python to try something myself, but likely not realistic.


Would like to raise one issue of definition: when is the first day to use for calculating FDD(x) at each point, x (shorthand for a two dimensional coordinate)?


Use a single, universal date for the whole map, i_start? This seems a poor solution to me. The problem with that is that the colder places will begin freezing before the warmer ones. The warmer places would still be having days above the reference temperature, Tref (either 0 or -1.8 degrees C, not sure that has been decided?) while the cooler places begin accumulating FDDs.

  A better solution imo would be to store a separate start date, i_start(x) appropriate for each point x on your 2-dimensional map grid.

Further, I would propose a suitable definition for i_start(x) as the start day that maximises the FDD at that point x.

That is, the FDD at point x on day n, FDD(n,x) is determined by stepping over days, j, and finding the maximum for:


FDD(n,x) = max. for i_start(x) of, sum[j=i_start(x),n] (Tref-T(j,x)).


The day i_start(x) only needs to be determined once for each x - just step through the days up to any day n well into the freezing season and record the value of i_start(x) that maximises it.


Has anyone encountered this as an issue? Does the above proposed solution make any sense?

22
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 03, 2017, 05:12:50 AM »
...
  However, the FDD daily map itself is actually dead easy to do given the daily temperature maps for the Arctic Basin. As I said, one simply increments the FDD value at each location by the degrees freezing for the day at that location. Done!

  That procedure gives a perfectly well defined FDD-to-date map.

   I would suggest also that this FDD is intrinsically interesting - it tells you how cold each location or region of the Arctic Basin has been during the freezing season. That extends greatly on e.g. the one parameter information available from the FDD 80N graph.

  The maps can be compared for different years. E.g. "has the Beaufort Sea been colder than usual this freeze season?"

 
 The FDD 80N graph itself can be derived from the FDD-to-date maps, as can FDD graphs for the entire Arctic Basin or for any other defined region. So the maps are useful for that purpose as well.

...

Thanks for you posts extending on my localized temperature post, slow wing.  I had hoped some might find this data 'intrinsically interesting' as I do.  You have provided the logical next step I was looking for, and my next project.   

--CB
Great stuff! Thanks for following up.

23
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 07:58:32 AM »
Thanks for your reply, Tigertown.

  I agree up to a point.

  However, the FDD daily map itself is actually dead easy to do given the daily temperature maps for the Arctic Basin. As I said, one simply increments the FDD value at each location by the degrees freezing for the day at that location. Done!

  That procedure gives a perfectly well defined FDD-to-date map.

   I would suggest also that this FDD is intrinsically interesting - it tells you how cold each location or region of the Arctic Basin has been during the freezing season. That extends greatly on e.g. the one parameter information available from the FDD 80N graph.

  The maps can be compared for different years. E.g. "has the Beaufort Sea been colder than usual this freeze season?"

 
 The FDD 80N graph itself can be derived from the FDD-to-date maps, as can FDD graphs for the entire Arctic Basin or for any other defined region. So the maps are useful for that purpose as well.




  Where the issues of drift etc. come in is when one tries to derive an ice thickness map from the FDD daily map, e.g. using the Lebedev formula. As you suggest, the corrections, or else the uncorrected deviations, might be quite large. How large? It might be quite interesting in and of itself to find out. To the extent the ice depth prediction has interest, correction procedures can be come up with and applied.

24
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 07:07:12 AM »
Yes, this FDD (Freezing Degree Days) is a nice idea to get a handle on the depth of ice expected.

The FDD 80N is just a one-parameter measure. Cognitive Bias has posted a couple of other such measures above, at #2438. Yet another one would be the average FDD over a defined boundary for the Arctic Basin "the FDD Arctic Basin".

 This freezing season's anomaly in the FDD 80N parameter appears to come largely from the Atlantic side, particularly around the Barents Sea area where the open water is - at least that is the impression I get from the daily temperature maps and temperature anomaly.

I'm wondering if FDD Arctic Basin would show quite as large an anomaly? Have the temperature anomalies been as large on the Beaufort Sea side of the Arctic Basin? I haven't followed it closely enough to confidently answer that one.


   As an extension to this analytical tool, a daily FDD map could be constructed from the daily temperature map for the freezing season up to the current date  ("FDD-to-date map") over the Arctic Basin. (Specifically, just add the "freezing degrees" for the day at each location to the accumulated FDD value at that location from yesterday's map.)

   Neglecting ice movement, such a map would predict - using the Lebedev formula or the other one - ice thickness at each date and for each location within the Arctic Basin (at least where there was no ice at the start of the freeze season, as well as where the initial thickness was known or estimated).

   Would that simple thickness prediction correspond well with the actual measured thickness at each location? It ignores factors such as water temperature and salinity below the ice. Even if not, would the difference give us information on those and other factors at each location? Also, the Lebedev parameterization could be assessed and improved.

  Unfortunately I have neither the time nor the coding wherewithal to create and keep current such an FDD-to-date map. But anyway that is a suggested extension to the interesting concept of FDD if anyone happens to be interested.

25
Arctic sea ice / Re: The 2016/2017 freezing season
« on: February 02, 2017, 03:30:53 AM »
My current understanding/prejudice is that the most reliable thickness data for the current Arctic sea ice is the Cryosat NRT data from CPOM:
http://www.cpom.ucl.ac.uk/csopr/seaice.html.

As I understand it, that data set is from actual measurements rather than models. Also, I haven't heard so far of any reason not to trust its accuracy.

 Is that fair? I have no reason for bias but am simply an amateur.



So I wanted to compare this year's status to previous years, using that site. Only certain data sets are readily available that I can see, and so the gif below shows some sort of apples-to-oranges comparison.

The frames are, in order
1) Latest 5km Grid of 28-day Thickness : 2/1/17 - 29/1/17 (shows for 200 ms)
2) Thickness over March+April 2011 (shows for 50 ms) = "Spring 2011"
3) Spring 2012
4) Spring 2013
5) Spring 2014
(Those are the only years I can see readily available.)

So basically its comparing the ice thickness around mid-January 2017 with that around the end of March for 2011 to 2014.

So we have to imagine how much ice will be added over the next month-and-a-half if we want to see if we are worse off, or better off, than in those previous years.

  The worst ice situation from those previous years was in 2013.

   As can be seen from the gif, the ice pack in the vertical middle of the plot - i.e. excluding the Beaufort, Chukchi and Bering Sea on the Pacific Side and the Barents, Kara etc on the Atlantic side - was not really worse than currently. Add another month-and-a-half of ice growth and that part might generally be thicker in Spring 2017 than it was in 2013.

(Say add about a half-metre of ice then, roughly:
dark blue -> light blue
light blue -> green
green -> yellow
yellow -> red
etc.)

So the vertical-centre part as described above will probably not be the weakness this Spring.

Instead, the worry is the Pacific and, particularly, Atlantic peripheral seas. These are seen to have much less ice than in previous years, albeit shown 1.5 months later.

The worst sea in the comparison is probably the Barents Sea. Unless the ice is added there, quickly and dramatically, the Barents Sea is likely to melt out early in the upcoming melt season. That, in turn, might make the whole Atlantic side into a 'kill zone' for any ice drifting over there during the melt season.

On the Pacific side, the Beaufort, Bering and Chukchi Seas might also melt out earlier in the 2017 melt season than they did in 2011-14, forming another 'kill zone', on the Pacific side. We already saw that feature in 2015 and, even more, last year.



  In summary, a quick comparison was made of the available CPOM CryoSat NRT Arctic sea ice thickness data for this January vs. Spring in 2011-14. The main conclusion is that the sea ice this melt season looks likely to be vulnerable on the Atlantic (mainly) and also Pacific sides. Now it's all up to the weather and currents over the next six months.



The gif needs a click to start.

26
Arctic sea ice / Re: The 2016/2017 freezing season
« on: January 28, 2017, 05:18:52 AM »
FOOW,

   Thanks for the sea surface height and surface salinity plots.

   Are they as extraordinary as they seem to an amateur such as me?  For example, the surface salinity just North of Severnaya Zemlya is not much less than that of the bulk Atlantic Ocean! The orange region extends to about the North Pole.

   Is that reliable? (Where does it come from? Is it e.g. derived from satellite measurements of sea surface height plus interpolating between buoy readings?)

   Presuming it's reliable, how anomalous is that for this time of year?

   Is it fair to say that the usual thermohaline depth structure must have largely broken down in the reddish (and, less so, orange) regions within the Arctic Basin proper? And, consequently, that any warmer Atlantic water transported into those regions is now more likely to mix from the storm churn than it is to sink due to any greater salinity and hence density? If so then is it reasonable to assume that any heat transported into those regions from the Atlantic currents from now on will largely be available to melt the sea ice where in past years it would not have been?

   And, as you have indicated, the high salinity regions appear to correlate with regions of sea ice damage as pointed out and plotted by A-Team.

   I have no expertise or background knowledge in this area but these plots appear to me like they could be important. Perhaps could you and others please give some more expert interpretation of these plots and what they mean for the Arctic sea ice? Thanks.

27
Arctic sea ice / Re: The 2016/2017 freezing season
« on: December 05, 2016, 10:08:07 AM »
A-Team, thanks very much for your continuing posts that have certainly helped with my understanding.

The bathymetry connection is fascinating.

So is it conceptually useful to separate some analyses into the 'deep' Arctic Basin and 'shallow' Arctic Basin, with an ocean depth scale of order 100m used for the partition?

Then 'shallow' corresponds largely to the Russian side as well as the CAA and peripheral seas on the Atlantic side. 'Deep' is most of the rest of the central Arctic Basin.

If 'shallow' then:
  - mixing processes such as waves and Ekman pumping - with characteristic depths scales in the tens of metres - can therefore reach over much of the ocean depth.
  - warm, heavy salty currents from the Atlantic and Pacific Oceans can still potentially mix with the surface layer of water, bringing heat and salinity to the ice at the surface.

If 'deep':
  - there is probably still a stable and persistent salinity gradient below of order 100 metres
  - the warm Atlantic and Pacific Ocean currents have already sunk to below that depth, and so below where they could potentially influence the sea ice.


Your wonderfully informative graphics in your post #1182
appear to show the ice having remained/formed preferentially over the 'deep' Arctic Basin and you have posted previously about the mixing and trapped heat retarding ice formation in - from memory - the ESS.

  With all the presumed mixing from storms this year, maybe the 'shallow' Arctic is in historically poor condition for ice formation and growth over the Winter? While the 'deep' Arctic might be expected to be less affected?
 

28
Arctic sea ice / Re: Piomas vs. CryoSat
« on: November 24, 2016, 02:21:02 AM »
Thanks diablobanquisa, that's very interesting.

Presumably they are all 28-day Thickness maps collecting measurements over 24/10 - 20/11?

So this is precise and well-calibrated for year-to-year comparisons?

It shows almost no ice thicker than 2 m at that time of year in 2011, then 2013 a big recovery year before falling away again.

This year at least has some thicker ice off the Canadian Arctic coastline but the overall extent is of course the lowest.

29
Arctic sea ice / Re: Arctic Image of the Day
« on: November 22, 2016, 06:32:40 AM »
Nice image, Cate!

It was taken by Patty Waymire and published in a National Geographic feature on climate change:
http://yourshot.nationalgeographic.com/stories/climate-change-focus/

"A solitary bear sits on the edge of one of the Barter Islands."

Barter Island (singular, according to Wikipedia) is on the Arctic Coast of Alaska:
https://en.wikipedia.org/wiki/Barter_Island

30
Arctic sea ice / Re: The 2016/2017 freezing season
« on: November 20, 2016, 01:01:05 AM »

.... just because 2016 is starting to superficially resemble earlier years (in terms of diminishing open water), it is not starting to resemble 2015 in terms of ice thickness (or its integral, total ice volume).


Quite true. 

Ice thickness formation has been in the literature since at least Bydin in 1933.  Lebedev in 1938 presented the formula: thickness (cm) = 1.53 * FDD ^ 0.59 (where FDD is Freezing Degree Days). Berillo in 1961 gave 1.33 * FDD ^ 0.58.   Chris Reynolds covers the basic thermodynamics that leads to these formulas in his post The Simplest Model of Sea Ice Growth

Eyeballing the current DMI N80 graph it appears we've accumulated about 600 FDDs since the end of the melt season.  Baseline would be about 1300 FDDs.  A thickness deficit of 700 FDDs would imply a reduction in thickness of 0.3m (based on 3100 projected FDDs compared to 3800 FDDs for recent years).

Temperatures can return to somewhere near normal and extent can return to somewhere near normal, but it's highly unlikely that the size of the FDD deficit can be recouped.  Ice is going to be significantly thinner come the 2017 melting season.

Thanks ktonine, very helpful post.

Do I have your calculations correct though?
"Berillo in 1961 gave 1.33 * FDD ^ 0.58"

FDD_baseline = 3800
FDD_2016proj = 3100

H_baseline = 159 cm
H_2016proj = 141 cm

H_deficit2016 = 18 cm.

So the predicted ice thickness in that scenario would be about 18/159 = 11% down from the baseline at the start of the 2017 melt season.


That is for new ice. For multi-year ice, both the fractional and absolute reductions in thickness will be less in this model.

31
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?

32
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.

33
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. 

34
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.

35
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.

36
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?

37
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:

38
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.

39
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...

40
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.

41
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:

42
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.

43
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.

44
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.

45
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!  :)

46
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.

47
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?


48
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.

49
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?

50
Arctic sea ice / Re: Latest PIOMAS update (September)
« on: September 25, 2016, 02:53:57 AM »
Thank you Michael, appreciated!

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