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Messages - ajouis

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1
Arctic sea ice / Re: The 2020 melting season
« on: September 05, 2020, 11:05:31 AM »
August 31 - September 4.

2019.
The beaufort sea ice has suffered strong winds and choppy seas during this week and losses have accelerated again. Quieter time ahead.
The Atlantic front has one or two of bad days ahead yet, but then the tendency of compacting will reverse very quickly.

What happens after 5 days: throw a coin. A minimum this weekend or early next week is guaranteed. Is it THE minimum? If it stays so for the next week, based on previous years dates, yes.

2
Arctic sea ice / Re: Melt Ponds
« on: September 04, 2020, 06:45:59 PM »
Great to see this reinvigorated forum. Melt ponds have a lot of non-intuitive aspects. The article pair below is rather surprising for the late date of discovery within the century of melt pond study. With first year ice becoming ever more abundant and melt occurring perhaps earlier via Arctic Amplification, the intricate processes described below become ever more important.

Brine exclusion during FYI maturation ends up on the ice surface, in interior channels, and as non-buoyant water that sinks, affecting stratification and inhibiting later mixing. The Polarstern scientists are already skimming ice off the surface before lowering gear and seeing connecting currents.

In the North Pole region, with half the area in melt ponds, some measuring as deep as 1.5m, what fraction of the ice volume in December will be completely refrozen melt ponds rather than thermodynamic bottom ice? Some fraction will have drained and so have lower topography which might have consequences for re-formation via trapping in the following melt season.

Arctic melt ponds form when meltwater clogs ice pores
Pond formation mechanism previously unknown
https://unews.utah.edu/melt-ponds/ popular account

In 2014, Golden, along with study first author Chris Polashenski of the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory and colleagues traveled aboard the U.S. Coast Guard cutter Healy to the Chukchi Sea, between Alaska and Siberia, to investigate massive algae blooms below the ice, which had been first observed in 2011. As part of their study they needed to measure the permeability of the ice. Permeability is a measure of how well interconnected voids and channels within a material allow fluid to flow through.

Their first attempt involved drilling a hole in the ice down below the “freeboard level,” or water table, to see how quickly the water filled the hole back in.

“It filled up to the freeboard level in about a second and a half,” Golden says, indicating the ice was too permeable to make a measurement. Next, the team tried to add water to the hole to see how quickly the water level re-equilibrated to the freeboard level. They planned several attempts, and noticed that in the second attempt, the water level fell much more slowly than in the first attempt.

“And then the third time was the charm,” Golden says. The team poured water into the hole and the level didn’t go down at all. “We formed a melt pond!” he says.

Intrigued, the team tested different levels of water salinity in boreholes and used dyes to trace the progress of the water through the ice. The team used red and green food coloring from the Healy’s kitchen. All of their experimentation pointed to a clear mechanism for melt pond formation.

“The freezing point of the fresh meltwater from snow is zero Celsius,” Golden says. “But the ice itself is maybe -1 or -1.5. The freezing point of seawater is -1.8. So basically, you’re getting this infusion of fresh water and there’s enough cold there to clog up the pores. You’re lowering the permeability of the ice by this process of freezing freshwater plugs into the porous microstructure.” With lowered permeability, the meltwater can form a pool on top of the ice.

Percolation blockage: A process that enables melt pond formation on first year Arctic sea ice
Chris Polashenski  Kenneth M. Golden  Donald K. Perovich et al
16 January 2017
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JC011994 journal account

Melt pond formation atop Arctic sea ice is a primary control of shortwave energy balance in the Arctic Ocean. During late spring and summer, the ponds determine sea ice albedo and how much solar radiation is transmitted into the upper ocean through the sea ice. The initial formation of ponds requires that melt water be retained above sea level on the ice surface.

Both theory and observations, however, show that first year sea ice is so highly porous prior to the formation of melt ponds that multi-day retention of water above hydraulic equilibrium should not be possible.

Here we present results of percolation experiments that identify and directly demonstrate a mechanism allowing melt pond formation. The infiltration of fresh water into the pore structure of sea ice is responsible for blocking percolation pathways with ice, sealing the ice against water percolation, and allowing water to pool above sea level.

We demonstrate that this mechanism is dependent on fresh water availability, known to be predominantly from snowmelt, and ice temperature at melt onset. We argue that the blockage process has the potential to exert significant control over inter-annual variability in ice albedo

While optical properties of individual ponds vary, the areal fraction of the surface that the ponds cover is by far the most important aspect of pond formation in determining spatially averaged albedo and solar partitioning.

On first year sea ice, early in the melt season, pond coverage is largely controlled by a hydraulic balance of meltwater inflows and outflows and the bathymetry of the depressions available for this water to pool in. Limited outflow pathways result in an accumulation of meltwater above sea level and large pond coverage on undeformed ice.

.Later in the melt season, pathways for water to pass between the ice surface and ocean become relatively unrestricted, first through the formation of large drainage holes, and later through the onset of permeability through the ice matrix [Polashenski et al., 2012]. After large levels of permeability are established, pond coverage is controlled by the fraction of the ice surface situated below sea level ...[many more pages of detail]

3
The forum / Re: Forum Decorum
« on: August 18, 2020, 05:14:15 PM »
Thank you ajouis . you are a breath of fresh air . b.c.


4
Wikipedia is not a reliable source for many, many topics.

sidd



5
Arctic sea ice / Re: The 2020 melting season
« on: August 02, 2020, 05:48:52 AM »
AMSR2 remote sensing instrument is showing a significant increase of sea ice area in the CAB.



I am expecting NSIDC sea ice area to follow suit in the next several days (especially the Central Arctic).

No it hasn't.  Clouds and fog have increased blocking the sensor.

Which is why NSIDC area in the cab isn't as effected uses different bandwidth.

I can't believe this had to be explained for the billionth time.

We have huge holes of of open water opening up within the ice pack and you know Bremen is highly obscured by clouds.

So you are intentionally sabatoging the discussion.

Don't bother replying for me.  I'm putting you on ignore. 



For what it's worth.    I'm sure there is many posters who think I'm just being bias.  Believe me I am rooting for a record low because it's interesting and inevitable.

But also extent and area are currently dead last.

But I call it as it is and this forum has worked so hard to shed our bias towards the end of the ice cap.

And we have a great community who has worked hard to inform ourselves about things like Bremen being obscured by weather.

This weather dude knows that and pisses all over that to press his agenda.

That's just lame.



6
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 01:05:32 AM »


Yep your going mad...

As others say, now the storm is weakening and forecast to move near to Greenland, the weather in theory looks favourable for the ice but again with the way this year has gone then never rule anything out.

I am sorry Paul, but I have not seen a forecast that looks favorable for the ice in a very long time. The low is weakening and moving south, but that does not mean favorable conditions for the ice.

It has done whatever damage it was going to do. At a minimum, it pushed ice south into warm waters and reduced concentrations in the main pack. If it caused Eckman suction of warm deep waters that will be even more important.

We don’t know the outcome of the storm, or the reverse dipole that has flooded the CAB with heat from WAA. However, if you have a crystal ball that says the weather is now favorable for the ice please share that forecast with us.

7
I think it has to do with the eddies and tidal forces occurring there.

8
With current sea ice records shattered already during the midst of the season, as well pronounced in the East Siberian Arctic Shelf ESAS region - basically just open waters, we ought to be particular cautious about the current environmental change opening up in front of our eyes.

via https://twitter.com/ZLabe/status/1284595460766707712

Quote
This scenario is now further fueled by prolonged record setting heatwaves. ..prolonged high average temperatures over 6 months and the record-breaking high of 38 ℃ recorded in Verkhoyansk on 20 June - a town roughly 600 km from the ESAS coast line. http://climatestate.com/2020/07/19/further-evidence-suggests-arctic-ocean-methane-storage-getting-more-unstable

Baked by midsummer sun, Arctic sea ice could face worst losses on record
Quote
Relentless high pressure and cloud-free skies have allowed the Arctic Ocean’s sea ice to plummet to its lowest mid-July extent on record. The persistent pattern sets the stage for what could be unprecedented losses by September – a long-feared next step in the Arctic’s erratic, climate-change–fueled lurch toward a potential “blue ocean” mode. https://www.yaleclimateconnections.org/2020/07/baked-by-midsummer-sun-arctic-sea-ice-could-face-worst-losses-on-record/
Quote
NSIDC: Air temperatures at the 925 mb level (about 2,500 feet above sea level), as averaged over the first half of July, were unusually high over the central Arctic Ocean—up to 10 degrees Celsius (18 degrees Fahrenheit) (Figure 2b). These above average temperatures were associated with high sea level pressure, centered over the East Siberian and Chukchi Seas (Figure 2c).

Arctic temperatures along the Russian coast were near to slightly above average. This is a sharp change from June, when, as part of the Siberian heat wave that has garnered much attention in the media, temperatures along the Siberian coast of the eastern Laptev Sea were 8 degrees Celsius (14 degrees Fahrenheit) above average.

It is likely these high temperatures, combined with ice motion away from the coast, initiated early ice retreat along the Russian coast, leading to the present low ice extent (Figure). Based on imagery from AMSR-2 processed by colleagues at the University of Bremen, the Northern Sea Route along the Russian coast appears to be largely open. https://nsidc.org/arcticseaicenews/2020/07/siberian-downward-slide/



Further Evidence suggests Arctic Ocean Methane Storage getting Unstable

At the ocean and atmosphere interface, the upper layer albedo effect vanishes with a lack of sea ice cover, subsequently creating a warmer surface layer, and perhaps altering the halocline https://www.sciencedirect.com/topics/engineering/halocline saltiness, temperature gradients, currents - shifting into a mode of a more productive melting regime.

The authors of the 2019 French study, Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic, noted, ‘..in addition to increased CH4 emissions from wetlands and thawing permafrost, increasing ocean temperatures could lead to the destabilization of methane hydrates on the Arctic continental shelf, potentially emitting large quantities of CH4.’

Further previous research highlights a new mechanism for subsea permafrost deglaciation

Quote
The scientists found that one of the reasons for extensive methane release from the bottom sediments of the East Siberian Arctic Shelf is the destabilization of underwater permafrost gas hydrates that interact with the salt solutions (sea water) migrating into the thawing submarine permafrost. http://climatestate.com/2019/06/19/new-mechanism-for-methane-hydrate-dissociation/

Salinity at 34m, jul18 2018-2020


Quote
New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm. https://uaf-iarc.org/2020/07/10/arctic-ocean-changes-driven-by-sub-arctic-seas/

9
Here's a stupid question.  Has anyone gone and plugged in an ice-free Arctic into an otherwise modern day starting conditions input to say, the GFS or EURO, to see how different the climate would be?  Do we have any idea how that vast swath of open water will change things?  I'm sure there's probably an entire thread on this somewhere but I'm not sure where to look.

10
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 11:36:52 PM »
Can you please provide evidence of ice stacking on top of ot self to maintain thickness???

Pressure ridges are all over but they are only a few meters wide.

Its truly astonishing how many different excuses you guys are coming up with to rationalize away the most prolific warmth(May-present) we have every seen in the arctic basin and the decimation its caused.

This idea that the ice is super compact is a joke that you can visibly dispel on worldview.




11
The politics / Re: Brexit...
« on: July 10, 2020, 05:10:47 PM »
paddy as it was a Brexit thread I assumed you were talking about europeans sanctions vis a vis the uk, only in this context does my above comment apply
Look mate, this 'ere is the brexit fred. Those bloody EUcrats are gonna put a big tax on our exports of cheese and we will have to pay more for their bloody oranges, and pay a fortune to drink English beer in benidorm. How much more can a true blue Honky Englishman take from these bloody furriners?

12
Arctic background / Re: Aerosol reduction effects
« on: May 22, 2020, 02:37:55 AM »
As stated elsewhere IMO cold spot in canada has more to do with wavy jetstream / reorienting center on greenland rather than north pole. While I am sure aerosols effect the weather I do not think they are as localized as that.

13
Arctic sea ice / Re: The 2020 melting season
« on: May 05, 2020, 03:19:14 PM »
does anyone think the increasing open water lead in the bering strait is the incursion of a warm current? It looks that way, especially given the shape and speed, but it could just have been a weak area given it's almost dead centre.
That open water was created by wind and movement of the ice.
If the forecast holds, the Chukchi and Bering Seas will start to see positive temperatures at the end of the week.

14
Arctic sea ice / Re: The caa-greenland mega crack
« on: April 28, 2020, 05:58:49 PM »
So I just checked that same area this morning and I'm just amazed at what I'm seeing right now. First and foremost is how clear it has been in that entire region. It's usually extremely cloudy there, but this has been the longest stretch without thicc clouds I have seen in the arctic since I've been following it. I'm not sure how these conditions will play out the rest of the year, but I can't imagine it being "good."

Either way, over the course of the last 24 hours it looks like drift has picked up significantly with a larger and more fragmented gap beginning to appear. After looking at the same date going back to 2014, nothing quite compares. Granted, there does appear to be a constant eastern/northeastern flow of ice, with cracks, but what makes this year unique is the already substantial gap and the amount of fractures within the central pack itself.

Feel free to take a look for yourselves, but my initial feeling is that this entire crack will emerge again this year. 

15
Arctic sea ice / Re: The 2020 melting season
« on: April 27, 2020, 05:53:28 PM »
This is so wild to me! Granted, I'm not attempting to say that April resembles September of 2019, but I am using this to show how the ice above Greenland continues to surprise me with its mobility. Ice is most certainly still held to the coast an inlets, however with so much sunlight, and lack of clouds, whatever darker areas will most certainly absorbing energy. Nonetheless, there is still much for to follow in such a dynamic system.


16
Arctic sea ice / Re: The caa-greenland mega crack
« on: April 22, 2020, 12:14:52 AM »
mega micro cracks, caa north greenland, apr21.  https://go.nasa.gov/2VIPG2i

17
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 30, 2019, 09:24:44 PM »
According to the 7/30 imagery, it appears as though (within reason and for hypothetical purposes) save for one section, it is almost possible to sail around Greenland. I'm not sure if I've ever known this to be possible. Depending on how July unfolds, I wonder if this will completely open up. I'm inclined to say it is, given the fact that the crack continues to expand north and the open water will be absorbing more heat. Either way, this is the single most notable formation of this season.


18
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 08:47:01 PM »
OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
could enhance ssts in the region, where thick ice is supposed to be, keeping volume down, and changing the safe ice reduit.
It might mean another change of paradigm in the arctic, which is one of the reasons why I opened this thread, to compile data to know whether this is the case, I have only been following the arctic for a couple of years, so I am only really aware of the north Greenland crack late summer last year.

Yes I understand better now. However, if in summer there’s a “Garlic press” like event (strong compaction against the CAA and Greenland) expect a lot of ridged ice to occupy that breach over the shelf, delaying the reappearance  of that gap that we witness now.

 I see typical events of the Arctic (drift towards America, Fram currents) as tending to keep the thing closed and with thickened and ridge ice. I agree with sailor above there should not survive in Winter, but I think beyond, it would  typically recover thick ice.

19
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 05:46:32 PM »
I've seen open water just north of the CAA several times, and north of Greenland last year, but having a nearly continuous stretch of open water along the entire North American continent, and for as long a period of time this year, is unprecedented, I believe.   Polynyas that recur in certain locations are often named, such as the North Water Polynya.  A 'full' list of Canadian polynyas [plus some inAlaska, Greenland and eastern Russia] .

Should this become a feature, I've proposed calling it the NAC: North American Crack.  Of course we could call it McCAG: Mega-crack - Canadian Arctic/Greenland: this doesn't 'look' like any other abbreviation...  Movement of ice along this boundary, of course, happens 'all' the time.  What is less usual is for the ice to pull away (and melt) along most of this boundary at one time, so maybe the NACP:  North American Coastal Polynya.

The Canadian list of polynyas identifies the location of un-named "major shore lead polynyas", including one along the entire North American continent.  So maybe the NASLP: North American Shore Lead Polynya.

See more discussion of polynya in Wikipedia, Encyclopedia Britannica and elsewhere.

[I share my opinions and you choose!]


I like the initiative to find a name for this feature. My understanding is that polynya refers to open water completely surrounded by ice and the crack doesn't meet that definition to the west.

I'm cool with crack or NAC until it gets bigger. When it hits 50k km2 or 100k km2, it become something else.

How about CABCOW? (Central Arctic Basin Coastal Open Water)

This is pretty much covers the entire region where the CAB comes into contact with land ( excluding small features like Svalbard and FJL. )

20
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 05:23:08 PM »
Ice is taking a shore leave. Likely comes back to serve next spring as the albedo enhancer. But the job is dull and increasingly difficult, so might leave alltogether some spring.

21
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 04:48:31 PM »
I've seen open water just north of the CAA several times, and north of Greenland last year, but having a nearly continuous stretch of open water along the entire North American continent, and for as long a period of time this year, is unprecedented, I believe.   Polynyas that recur in certain locations are often named, such as the North Water Polynya.  A 'full' list of Canadian polynyas [plus some inAlaska, Greenland and eastern Russia] .

Should this become a feature, I've proposed calling it the NAC: North American Crack.  Of course we could call it McCAG: Mega-crack - Canadian Arctic/Greenland: this doesn't 'look' like any other abbreviation...  Movement of ice along this boundary, of course, happens 'all' the time.  What is less usual is for the ice to pull away (and melt) along most of this boundary at one time, so maybe the NACP:  North American Coastal Polynya.

The Canadian list of polynyas identifies the location of un-named "major shore lead polynyas", including one along the entire North American continent.  So maybe the NASLP: North American Shore Lead Polynya.

See more discussion of polynya in Wikipedia, Encyclopedia Britannica and elsewhere.

[I share my opinions and you choose!]

22
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 01:51:17 PM »
I won't pollute this topic with my wildly uneducated guesses about the future of this crack, but I do want to say that watching such things arise and develop as we slide ever closer to the first BOE and beyond is one of the more grimly fascinating parts of watching the doings on top of the world.

23
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 11:37:50 AM »
I go with ice island circling around the pole. Northern Greenland can get surprisingly hot.

24
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2019, 11:13:50 AM »
It's probably reasonable to expect The Crack to become a standard in future melt seasons. I wonder how this will affect future minimums and especially the somewhat arbitrary 1 million km2 BOE threshold.

If Northern CAA & Greenland can no longer be counted as the last bastion of thick MYI, do we such a place anywhere in the Arctic?  Will the last remaining ice be an ice island circulating at the pole, and if so, is such development a start to a BOE or the Arctic Ocean to become a seasonally open sea.

Interesting.

25
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 11:22:28 PM »
I am seeing some people here speculating that this season might not be a record breaker

Very high likelihood it will be a record breaker (in the most important metric -- even with the major difficulties in assessing it -- volume).

But you probably mean extent, which is large squares covered by almost no ice in some years... For that we might not know until we see the wind patterns in the week or two immediately preceding minimum.

26
Arctic sea ice / Re: The 2019 melting season
« on: July 14, 2019, 01:48:52 PM »
Quote
Looking at the most current bremen amsr2 map, a few things stand out. 
Very good analysis.

27
Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 03:39:50 PM »
it s been there for at least 4 days, so it might be something

I see what you mean -- but faint and small until today. Hard to find a cloudless day to verify it on Worldview. The snow in that region does seem to have just melted out within the last few days, so maybe it is something. It will be interesting to see if it persists.

https://go.nasa.gov/2Xxjlu2

28
Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 01:54:45 PM »
...
There is also a weird band just east of the pole if anyone knows what it is?
I agree with you're analysis -  the ice melt  looks mostly very bad for 2019.
The expression "East of the pole" tripped me up for a short while.
But the feature to the right of the pole on this chart?
I'm a mathematician not a sea-ice expert, but..
The  dark vertical lines maybe the effect of compression
of more rounded areas of  lower concentration by general
drift to the right toward  Svalbard?
i had an hunch that it was related to ridging, that would be in agreement with your analysis.
On the other hand, at this latitude "low concentration" on that map is more likely to be meltponding than anything else, so either there are areas that are starting to get lower concentration in the north pole, which is a very bad sign (maybe related to the fram export), or it is maybe related to some peculiarities of the terrain that create that particular shape of melponding, like an increased elevation  that has the water accumulating at the base of it (guess that could be a consequence of ridging too), although the scale seems quite big for something so regular.
I am kinda used to the west east paradigm, as I do a lot of things with maps, but I guess in this case south would be more correct
Yes - could well be  melt-ponding, showing up as low concentration,  next to a ridge.
And you'll never be wrong if you say it's south of the pole -
of the North pole anyway.

29
Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 06:34:18 AM »
When you type 'albedo' in the search field, you'll get tons of results for it from this thread on the first page. It is widely discussed.

There are great graphs made by @Tealight >> https://cryospherecomputing.tk/NRTawp.html

30
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 01:40:53 PM »
 I doubt the 80N band remains saved from the onslaught, perhaps enjoying a temporary relief, by the SMOS map is pretty clear

31
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 04:55:15 AM »
Even if 2019 does not end up below 2012, the SIPN estimates all hovering just above 4 million km2 are historically low

Walsh, J. E., W. L. Chapman, and F. Fetterer. 2015, updated 2016. Gridded monthly sea ice extent and concentration, 1850 onwards, Version 1.1. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media. http://dx.doi.org/10.7265/N5833PZ5.

As for the horse race with 2012, am I the only one thinking that most of the SiPN estimates, with average of 4.2 km2 extent at minimum, are too high?  Possibly because they are based on historical correlations that no longer apply to a new Arctic sea ice regime where all the ice older than 2 years may be virtually extinct by the end of 2019 (except for nooks and crannies in CAA).

   Perhaps I am overreacting to latest NSIDC Arctic sea ice concentration image.  To me it looks like a pile of slush that could be flushed out through the Fram Strait with the right combination of warmth, clear skies and a couple of storms.  It does not look like an ice pack with enough resistance to withstand the remaining 45% of melt season.


32
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 01:51:00 AM »
The fast ice nearer the delta broke up extensively about a week ago (it disappeared long ago right next to the delta).  The ice now breaking up in the image was spotted by grixm yesterday.  Today, there are many more cracks in this area, which to me indicates ice that has passed a certain threshold of integrity and thinness.  Melting may be rapid from here.
Do you think we will be able to use the upcoming piomas data to get the threshold where sea ice breaks apart this season?

An interesting idea!  Maybe this would be done retrospectively first... where did ice break up in the past and what was Piomas 'saying' at that point?  Are there correlations with indicated Piomas thickness and time of fracturing?
   
But all in all, I would be hesitant, since Piomas is modeled, not measured, and its output has a general quality to it (as would be expected).  And I imagine so much probably depends on ice quality as well as thickness when it comes to ice breaking up.  And also, are we maybe talking about fast ice in your question, because much of the pack ice is already pretty rubbly already?  Having shot my mouth off (something of a problem I regret to say) I now step aside and let the experts take charge.

33
Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 03:41:50 AM »
My thoughts ...

Exactly! Volume is the key.

Or at least it's a helluvalot better than 2D (extent/area) measures, although it still doesn't incorporate other properties like strength, density, etc. But hopefully it broadly correlates with them.

And we can't measure volume. I'm skeptical about models like PIOMAS, given how many unknowns there are, likely with increasing importance. Hopefully ICESat-2 will help soon (https://nsidc.org/data/icesat-2/products/level-3b).

At equal volume, 2D minimums can differ dramatically based on ice distribution, and can even be heavily influenced by winds even in the week(s) immediately prior to minimum. This seems to account for much of the supposedly huge anomaly in 2012 -- the PIOMAS volume residual (insofar as it can be trusted) wasn't nearly as high as extent. Are we trying to measure September winds, or ice melt?

The ice goes from meters deep to cm's to mm's to... poof! 2D measures detect only the poof.

34
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 06:49:35 PM »
I haven t seen the university of Bremen/ asmr2 general area and extent pop up in a while.
I do think they are very useful as they have a thinner grid, does anyone have the most recent iteration and/or where I can find it?
Welcome ajouis. I use these bookmarks regularly:
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png
Extent and area for the Arctic Basin itself, for 3 algorithms with different grid sizes.

https://sites.google.com/site/arcticseaicegraphs/regional
This is the regional AMSR2 extent and area by Wipneus, based on the University of Hamburg algorithm with a 3.125 k grid. Wipneus also has more downloadable files and graphs on his site, at the address provided by Neven above.

https://seaice.uni-bremen.de/start/
https://seaice.uni-bremen.de/data/amsr2/today/extent_n_running_mean_amsr2_previous.png
Uni Bremen's sea ice web site, with several useful sub-pages, including the extent chart.

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