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Pagophilus

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Re: The 2019 melting season
« Reply #3100 on: July 02, 2019, 02:53:22 PM »
Pagophilus, I don't want to be snipped by the owner two days in a row so I'll just say, that's the way I understand dispersion vs export as used in this forum, and Fram Export in particular does not generally have to do with dispersion (as understood in this Forum)
I bow to your expertise.  I am just arguing that export, especially Fram export, is (on a system-wide basis) effectively a form of ice spreading out (and becoming more susceptible to melting). 

And I hope you don't get snipped -- I appreciate very much how your comments often go 'against the grain' of general sentiment, making us think more critically.

cavitycreep

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Re: The 2019 melting season
« Reply #3101 on: July 02, 2019, 03:05:32 PM »
Sea ice concentration, June 17 – July 1

Huge export of ice coming down into the Fram (I wonder how much of that is MYI).

ESS, Laptev, and Beaufort are lighting up.

CAA is continuing to dwindle away.

peterlvmeng

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Re: The 2019 melting season
« Reply #3102 on: July 02, 2019, 03:11:03 PM »
It seems unusual to me the wind coming from south Asia to the Bering Strait. I don't see the normal jet stream. Instead, a flow south to north. It is coming a lot of heat to the Arctic, with this wind pattern?

https://earth.nullschool.net/#current/wind/isobaric/700hPa/orthographic=-212.00,61.11,316

The pattern of subtropical high pressure and Indian dipole oscillation play an important role. If you look at the 500hPa geopotential, you will find the subtropical high pressure of northwest pacific ocean is relatively weak although governing a larger area. Especially, the high presssure have not intrude west to govern the east China, yet. The positive indian dipole oscillation also means the summer South Asia monsoon is strong. What's more, a Typhoon is forming in South China sea to accelerate this mechanism. It is now pumping more heat and moisture through South Asia to the northwest edge of subtropical high pressure.

The SST of north Pacific ocean is cold along Russia side while warm along the Alaska side. This helps to form high pressure ridge along the Alaska and continue pump heat and moisture through mid latitude to the arctic.

Summary, the reason lies in that South Asia monsoon is strong because of positive IDO and subtropical high pressure in northwest pacific ocean is weak because of El-nino.
« Last Edit: July 02, 2019, 03:19:05 PM by peterlvmeng »

ajouis

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Re: The 2019 melting season
« Reply #3103 on: July 02, 2019, 03:14:21 PM »
Thanks for this.  The AMSR2 maps are terrific, but they are also notorious for showing fleeting areas of 'lower concentration', sometimes the result of temporary surface melting due to temporary weather conditions over the ice.  So taking any one AMSR2 map and relying on it to show a long-term trend of the internal condition of the ice pack is risky at best.
Fair point, illustrated by the huge flooding of the ice in the ess that was revealed to be ephemereal, but currently it seems to do the opposite. As i pointed out in an earlier post, there seems to be an artifact that s artificially increasing the concentration in some parts of the ess close to the chuchki. I think it s because of the peculiar way it spreads, that is too close for the sensors to deciphere, but there is definitely more open water now than a few days ago, and even then it was not 100 concentration as it is showing now on the bremen map ( there is satellite image of it somewhere on this thread that shows the fragmentation)
« Last Edit: July 02, 2019, 03:21:11 PM by ajouis »

Pagophilus

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Re: The 2019 melting season
« Reply #3104 on: July 02, 2019, 03:36:00 PM »
Sea ice concentration, June 17 – July 1

Huge export of ice coming down into the Fram (I wonder how much of that is MYI).

ESS, Laptev, and Beaufort are lighting up.

CAA is continuing to dwindle away.
Thanks again for these vivid, useful animations.

Your emphasis on the Fram export is I think important.  That export is set to continue fairly strongly for the next three days, with winds driving export fading thereafter, but not reversing.  We only 'see' this Fram export on animations such as yours because the ice melts in the Greenland Sea about the same rate as it arrives.

One can almost sense the 'squeezing' of the main pack towards Greenland, and particularly the Fram area on your animation.  Perhaps subjective on my part

The continued disappearance of ice from the Kara and Chukchi, and the ever-wider yawning of the Laptev bite are also notable.  Will upcoming wind patterns send the ice a little more towards the Siberian side and close that yawn somewhat?


FishOutofWater

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Re: The 2019 melting season
« Reply #3105 on: July 02, 2019, 04:19:08 PM »
Most of the discussion about dispersion is pointless because we don't have a direct measure of ice dispersion. The area vs extent figures include the effects of melt ponds. We know from published research that early melt ponds are important to extent drops later in the summer. Thus the conflation of the effects of dispersion and melt ponds is a major problem in our discussions of dispersion, as Neven gently noted. As someone trained in science, not diplomacy, I do not tend to be so gentle.

Available data sets, such as JAXA extent, show that this year is running neck and neck with 2012. However, the distribution of early melt ponds, open water and thick ice is quite different. The weather has been different.

One factor that is worse this year is stored heat in the Pacific water layers, in particular, the summer water layer. Large amounts of heat have built up in the Chukchi and Beaufort seas at depths of 50m-100m. Moreover, heat in the Atlantic water layer has increased over the past several years. I'm uncertain about how the Atlantic layer heat now compares to 2012, however. What is clear to me is that late summer cyclones on the Siberian or Alaskan side of the Arctic ocean could stir up this heat like the GAC did in 2012. On the other hand, cyclones over the Canadian side could bring a cool close to the melt season and no new record this year. Late summer cyclones between the CAA and the pole have been good for the ice in recent recovery years because they stir up icy cold fresh water that cools the atmosphere.

peterlvmeng

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Re: The 2019 melting season
« Reply #3106 on: July 02, 2019, 04:23:43 PM »
ECMWF weather forecast is very interesting right now. A cyclone is going to churn up the Beaufort slush, transport towards the Greenland Sea and especially the Barentsz Sea continues, and will be intensified even by a relatively large cyclone that is said to reach 972 hPa on D5. This cyclone will also pull in lots of more warm air from Siberia, and further increase the open water in the Laptev Sea, while pushing ice away from the ESS coast.

The question is what will come after this. If we return to the set-up with high pressure dominating over the Beaufort Sea, 2019 will definitely end up in the Top 3. But I would be surprised if it doesn't end up in the Top5 already.
Yes, I totally agree with you, Neven. Although we cannot precisely predict whether the minimum area will break record, the upper boundary of minimum sea ice area is so obvious that this year will not good. And I came up with a simple melting ice heat transfer correlation. It is rough but is proper to deliver my view.
Q=h*delta T* A
Q is the heat the ice received
h is the overal heat transfer coefficient covering all the factors, such as solar radiation, wind, currents
delta T is the average temperature difference between air and ice temperature
A is the heat transfer area.

A sunny day (no high speed wind)
delta T is large (supposing deltaT=3)
h is small (supposing h=1)
A do not change (supposing A=1)

So the Q=3*1*1=3

A warm day ( with storm weather)
delta T is not so large (Supposing deltaT=1.5)
h is big because of turbulence(supposing h=3)
A depends on the thickness of ice(supposing ice is thin and easily be fractured A=1.5) then Q=1.5*3*1.5=6.75
(supposing the ice is strong A do not change A=1)
Q=1.5*3*1=4.5

A cold day (with storm)
delta T is small (Supposing deltaT=0.5)
h is big because of turbulence(supposing h=3)
A did not change so much (supposing A=1)
Q=0.5*3*1=1.5

So it is interesting to see the power of warm storm(2012 GAC)affects the melting ice, also the power of sunny weather (2007 extremely hot arctic summer), and the power of relative cold storm( 2016 stormy weather in arctic, the temperature in July and August is not warm even, but the ice is so thin and could be easily fractured) .

What I want to mention is that once the ice becomes thin and easily fractured, the storm becomes so important to influence the arctic rather than sunny weather. More storms, larger theat transfer coefficent h, and larger heat transfer area A, you do not need to beg the arctic will cool down tremendously becasue of global warming!, thus delta T will not be too small. So let us wait for the storm in ARCTIC!

SMN444

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Re: The 2019 melting season
« Reply #3107 on: July 02, 2019, 04:46:52 PM »
The sea ice extent had a 298K drop yesterday to 9.19M sq. km.  This may be an anomaly but other than the number posted for 6/30 (+25 sq. km), each day for the last week has had a drop of 97K or more averaging 128sq km lost per day. 

ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02135/north/daily/data/N_seaice_extent_daily_v3.0.csv

Days to drop from 10M sq. km to 9M sq. km
2019 8 days (est.)
2016 12 days
2012 8 days
2007 6 days

It's also worth noting that in 2012 we dropped below 9M on 7/2 and is the earliest in the season to date.

binntho

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Re: The 2019 melting season
« Reply #3108 on: July 02, 2019, 04:55:14 PM »
It seems to me that we have been using the words dispersion and export quite happily for the last several years without having to wrangle about what the words actually specifically mean down in the Bayou.

As someone who speaks English as a second (or even third) language, I am at times amazed at the low quality English used by some of the native speakers on the forum, with grammatical non sequiturs, embarassing spelling mistakes and word salads that would stretch the abilities of the the greatest of sauciers to dress palatably.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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cavitycreep

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Re: The 2019 melting season
« Reply #3109 on: July 02, 2019, 05:00:34 PM »
I'm not sure what my fascination is with this area of the Laptev but I keep noticing interesting cloud and wind patterns originating here.

Look at all of that melt happening on 21 June, then you can see the clouds coming from the eastern landmass, blowing south west (or vice versa, possibly). They correlate almost exactly with the sea ice concentration loss as they blow over them (use the 120 as a gauge). I'm guessing that these are wind shears moving either warm water or warm air.

On other days though, such as on 24 June, you can see a weather system that creates melt for the day over a certain area; I have another image where that weather system moves out further east but you can only have four attachments per post.

Shouldn't we be seeing the opposite effect from day time cloud coverage? Unless these are actually rain clouds.
« Last Edit: July 02, 2019, 05:11:47 PM by cavitycreep »

Sterks

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Re: The 2019 melting season
« Reply #3110 on: July 02, 2019, 05:03:48 PM »
Most of the discussion about dispersion is pointless because we don't have a direct measure of ice dispersion. The area vs extent figures include the effects of melt ponds. We know from published research that early melt ponds are important to extent drops later in the summer. Thus the conflation of the effects of dispersion and melt ponds is a major problem in our discussions of dispersion, as Neven gently noted. As someone trained in science, not diplomacy, I do not tend to be so gentle.

I was thinking in the GICE data of PIOMAS there is an estimate of dispersion implicit, since every element comes with a distribution of thicknesses. If the thickness=0 bin exists and is zero, it means the pack is compact. If the thickness=0 bin exists and has a different than zero value, that's open water within the pack and our measurement of dispersion.
Of course one have to believe the model, the zero thickness element must exist, and then  put the effort to map this "dispersion proxy"
Edit: From Dosbat, the zero th bin exists
http://dosbat.blogspot.com/2015/04/what-is-piomas-gice.html?m=1

ArcticMelt2

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Re: The 2019 melting season
« Reply #3111 on: July 02, 2019, 05:11:37 PM »
https://twitter.com/AlaskaWx

Quote
June 2019 sea surface temperature departures from 1981-2010 normal. Virtually entire Bering Sea north of 59N & Chukchi sea south of ice edge more than 2.5C (4.5F) & large areas much warmer. Impacts to communities & ecosystems continue. #Arctic #akwx @Climatologist49 @amy_holman


Pragma

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Re: The 2019 melting season
« Reply #3112 on: July 02, 2019, 05:14:56 PM »
It seems to me that we have been using the words dispersion and export quite happily for the last several years without having to wrangle about what the words actually specifically mean down in the Bayou.

As someone who speaks English as a second (or even third) language, I am at times amazed at the low quality English used by some of the native speakers on the forum, with grammatical non sequiturs, embarassing spelling mistakes and word salads that would stretch the abilities of the the greatest of sauciers to dress palatably.

+1 If something is worth saying, then it's worth taking the time to say it clearly. Text/email is bad enough for misunderstanding as it is.

Also, I don't understand, in the context of dispersion, why it matters where the ice is going.

Export is fine when talking about imminent ice loss, but to imply that ice is not dispersed because it is exported is silly and unnecessary. It sounds like an accountant talking about a tax loophole :).

Ice south of the Fram is still counted in extent, area and volume regardless of whether it has a shipping label on it or not.

LDorey

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Re: The 2019 melting season
« Reply #3113 on: July 02, 2019, 05:32:20 PM »
So I was playing with the various tools trying to quantify in my own mind how likely it is we'll beat 2012 and came up with this... this is ice today vs 2012 one month from now, and then looking at the likely hood those areas will be gone as of a month from now... based on the current concentration on those areas..... and taken in the context of the weather / winds for the next week...and well YIKES! :o 

Please note I'm not saying it'll melt exactly like this and in a month it'll look exactly like 2012, (in fact I highly doubt it), but its very much in the realm of possibility that a lot of the area's that 2012 was missing a month from now is going to melt out to a greater extent in the next month...been mostly lurking here for years, and usually by around this point in the year, I'm starting to relax and think okay, so it probably wont be this year we beat 2012... this year though... exciting times :)





johnm33

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Re: The 2019 melting season
« Reply #3114 on: July 02, 2019, 05:32:44 PM »
Looks like Atlantic waters have met Pacific waters by Amundsen/Banks and are doing the do-si-do

Pagophilus

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Re: The 2019 melting season
« Reply #3115 on: July 02, 2019, 05:40:10 PM »
It seems to me that we have been using the words dispersion and export quite happily for the last several years without having to wrangle about what the words actually specifically mean down in the Bayou.

As someone who speaks English as a second (or even third) language, I am at times amazed at the low quality English used by some of the native speakers on the forum, with grammatical non sequiturs, embarassing spelling mistakes and word salads that would stretch the abilities of the the greatest of sauciers to dress palatably.

Agree with you on many points, but surely getting clear on terms we use helps work against the 'word salad' responses you are writing about.
 
( It's embarRassing, by the way...   ;)    Not that spelling counts a whole lot, as long as the meaning itself is clear, but the irony was a little too delicious to pass over... sorry!)
« Last Edit: July 02, 2019, 05:58:39 PM by Pagophilus »

gerontocrat

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Re: The 2019 melting season
« Reply #3116 on: July 02, 2019, 05:42:00 PM »
As someone who speaks English as a second (or even third) language, I am at times amazed at the low quality English used by some of the native speakers on the forum
As Douglas Piranha would say "some of the native speakers are Americans". ("Douglas was the worst, he used... sarcasm. He knew all the tricks, dramatic irony, metaphor, pathos, puns, parody, litotes and... satire. He was vicious.")

Ice south of the Fram is still counted in extent, area and volume regardless of whether it has a shipping label on it or not.
True but I think people are looking forward to the immediate future when talking about dispersion and ice export. The life expectancy of ice depends on where it is ? It is reasonable to assume that in July open water created in the CAB, for example, by Fram export will not freeze over, while the ice sent down the Fram is doomed to die pdq.
"Para a Causa do Povo a Luta Continua!"
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Pagophilus

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Re: The 2019 melting season
« Reply #3117 on: July 02, 2019, 05:48:08 PM »
So I was playing with the various tools trying to quantify in my own mind how likely it is we'll beat 2012 and came up with this... this is ice today vs 2012 one month from now, and then looking at the likely hood those areas will be gone as of a month from now... based on the current concentration on those areas..... and taken in the context of the weather / winds for the next week...and well YIKES! :o 

Please note I'm not saying it'll melt exactly like this and in a month it'll look exactly like 2012, (in fact I highly doubt it), but its very much in the realm of possibility that a lot of the area's that 2012 was missing a month from now is going to melt out to a greater extent in the next month...been mostly lurking here for years, and usually by around this point in the year, I'm starting to relax and think okay, so it probably wont be this year we beat 2012... this year though... exciting times :)

+1   Very nice.  I had not thought about doing future tense stuff in this manner.  Focuses the predictions in at least some direction if 2012 is seen as been similar in some ways to 2019.

Pagophilus

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Re: The 2019 melting season
« Reply #3118 on: July 02, 2019, 05:57:43 PM »

Ice south of the Fram is still counted in extent, area and volume regardless of whether it has a shipping label on it or not.
True but I think people are looking forward to the immediate future when talking about dispersion and ice export. The life expectancy of ice depends on where it is ? It is reasonable to assume that in July open water created in the CAB, for example, by Fram export will not freeze over, while the ice sent down the Fram is doomed to die pdq.

This is a problem that comes up over and over in science and in almost any discussion.  I think much can be clarified by people first defining the system they are analyzing.  So, if we define the system/area we are discussing as the CAB, then it becomes clear that spreading of ice in the CAB can be said to be dispersion, and ice spreading out the CAB can be said to be export.

ArcticMelt2

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Re: The 2019 melting season
« Reply #3119 on: July 02, 2019, 06:01:09 PM »
https://twitter.com/Weather_West

Quote
Southern Alaska's ongoing #heatwave is expected to intensify significantly over coming week. Strength of high-pressure ridge at mid-levels of atmosphere may exceed all-time records over much of state. Surface temperatures may also reach all-time records in southern areas. #AKwx



Quote
All-Time record heat possible this weekend in parts of Alaska under huge heat ridge. Anchorage will challenge it’s all-time record of 85 in 1969. Pictured here forecast temps Sunday from the Euro.


BenB

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Re: The 2019 melting season
« Reply #3120 on: July 02, 2019, 06:02:08 PM »
In the context of this forum, the terms generally seem to have been used as follows:

Export: the movement of sea ice out of the central pack, generally to an area where it will almost certainly melt out, such as the Greenland Sea, Barents Sea, and to a lesser extent the Beaufort Sea. And, of course, through Nares into Baffin Bay. Export is a process.
Dispersal: ice spreading out and becoming less compact, not necessarily to somewhere it will melt out. Dispersal is also a process.
Dispersion: the extent to which there are lots of small polynyas between the ice floes in an area. Dispersion relates to the state of the ice, and not to the process that created it. Also sometimes used to mean the same as dispersal.

Export may therefore facilitate dispersal, leading to dispersion. That's my take, anyway.  8)

ArcticMelt2

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Re: The 2019 melting season
« Reply #3121 on: July 02, 2019, 06:03:06 PM »
https://twitter.com/NWSWPC

Quote
July 4th-7th: Record breaking temperatures are forecast across Alaska through this weekend as a strong upper level ridge parks over the state.








Sarat

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Re: The 2019 melting season
« Reply #3122 on: July 02, 2019, 06:08:14 PM »
In the vein of Alaska heatwave, I'm not sure if anyone already mentioned this, but globally June 2019 was the warmest on record (*Edit: for the month of June).

And much warmer in Europe... I have not found the data for the Arctic yet... but I'm sure it will come soon.

https://climate.copernicus.eu/record-breaking-temperatures-june

« Last Edit: July 02, 2019, 06:26:03 PM by Sarat »

Koop in VA

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Re: The 2019 melting season
« Reply #3123 on: July 02, 2019, 06:09:25 PM »
So I was playing with the various tools trying to quantify in my own mind how likely it is we'll beat 2012 and came up with this... this is ice today vs 2012 one month from now, and then looking at the likely hood those areas will be gone as of a month from now... based on the current concentration on those areas..... and taken in the context of the weather / winds for the next week...and well YIKES! :o 

Please note I'm not saying it'll melt exactly like this and in a month it'll look exactly like 2012, (in fact I highly doubt it), but its very much in the realm of possibility that a lot of the area's that 2012 was missing a month from now is going to melt out to a greater extent in the next month...been mostly lurking here for years, and usually by around this point in the year, I'm starting to relax and think okay, so it probably wont be this year we beat 2012... this year though... exciting times :)

Yes, but don't forget that the GAC of 2012 happened shortly after your 8/1/12 end date.  So it is perhaps worthwhile to also take a peak at what happened between 8/1/12 and 8/15/12.

I'm not able to insert the image at the moment but going to the NSIDC Comparison Tool (link below) is also instructive.

http://nsidc.org/arcticseaicenews/sea-ice-comparison-tool/
« Last Edit: July 02, 2019, 06:14:58 PM by Koop in VA »

SteveMDFP

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Re: The 2019 melting season
« Reply #3124 on: July 02, 2019, 06:28:05 PM »
It seems unusual to me the wind coming from south Asia to the Bering Strait. I don't see the normal jet stream. Instead, a flow south to north. It is coming a lot of heat to the Arctic, with this wind pattern?


Dang.  Quite remarkable.  Seems the arctic has contracted the Hong Kong flu.

Shared Humanity

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Re: The 2019 melting season
« Reply #3125 on: July 02, 2019, 06:35:47 PM »


Huge export of ice coming down into the Fram (I wonder how much of that is MYI).



Far less than in years past as there is far less MYI to export.

cavitycreep

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Re: The 2019 melting season
« Reply #3126 on: July 02, 2019, 06:39:38 PM »


Huge export of ice coming down into the Fram (I wonder how much of that is MYI).



Far less than in years past as there is far less MYI to export.

Ha, I should've clarified: how much of this export consists of the MYI that's left?

The ice coming out is from a one-two punch in the days leading up to it. The ice north of the Greenland coast is pushed up before being blown back south-east into the Fram.

Pagophilus

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Re: The 2019 melting season
« Reply #3127 on: July 02, 2019, 06:42:26 PM »


Huge export of ice coming down into the Fram (I wonder how much of that is MYI).



Far less than in years past as there is far less MYI to export.

Good to have this experienced perspective.  It is also true, is it not, that the less MYI remains in the CAB, the more significant the loss of that remaining MYI becomes?

be cause

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Re: The 2019 melting season
« Reply #3128 on: July 02, 2019, 06:44:43 PM »
CC .. take a look at Uniquorn's or A-team's gifts in Test space .. you could extrapolate forward .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

ArcticMelt2

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Re: The 2019 melting season
« Reply #3129 on: July 02, 2019, 06:55:04 PM »
And much warmer in Europe... I have not found the data for the Arctic yet... but I'm sure it will come soon.

https://climate.copernicus.eu/record-breaking-temperatures-june


Excessing past record the average temperature per month by one degree for a huge region is amazing. Perhaps this is another sign of the approaching catastrophic warming (the inclusion of an increasing number of feedbacks).

The area of Europe exceeds the area of Greenland.

RoxTheGeologist

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Re: The 2019 melting season
« Reply #3130 on: July 02, 2019, 07:00:21 PM »
Hello, can you look at
https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-06-29-T00%3A00%3A00Z&z=3&v=-835137.1514222269,-920779.3466764247,-507457.1514222269,-748875.3466764247&ab=on&as=2019-06-28T00%3A00%3A00Z&ae=2019-07-01T00%3A00%3A00Z&av=3&al=true

it's part of CAA. It was the bluest fast ice I could see. The ponds must have been deep there. And a few days ago it started to be infected by some growing white thing (run animation). Guess it's not much freezing, at around 0-7deg C, and it started from shores and older cracks. Is it pond draining before it disappear maybe then?

When a melt pond forms, water would try to drain through cracks in the ice. When the water below  is cold, the water coming from above would freeze at the bottom of the ice. The melt pond is now sealed, meltwater can accumulate on top.

When the water below the ice is warm though, the sealing effecct will stop. Now the water can drain through the ice freely. I think this is what's going on here.

I'm not sure this is totally correct. The water in the meltpond will seep into cracks in the underlying ice and freeze there as has apparently been confirmed in direct observation. And this will happen even with strong bottom melt ongoing as well, i.e. this freezing is not caused by the underlying sea temperatures, but the internal temperature of the ice. But at some point the structural integrity of the ice is not strong enough, or the internal temperature is not low enough, and the cracks stay open and once the water starts flowing, I guess the cracks will widen very quickly, leading to very rapid loss of surface water.

I suspect its the temperature, even if the ice 'opens' initially the underlying seawater starts the melt season at -1.8°C.; or close to it, depending on the salinity. It doesn't take much refreezing fresh water to warm the ice to > -1.8°C throughout it's thickness. Perhaps we see melt ponds disappear when the ice starts to float on much fresher water (bottom melt, draining melt ponds), so there isn't the available energy sink to refreeze the base of the melt pond. Once the base of the ice/surrounding water is 0°C then the water may drain away.

Rainfall doesn't melt a lot of ice on it's own. 1/83 per °C. 1 m of rain at 4°C only melts 5cm of ice. I think the fact that it isn't falling as high albedo insulating snow is far more important.

cavitycreep

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Re: The 2019 melting season
« Reply #3131 on: July 02, 2019, 07:11:21 PM »
CC .. take a look at Uniquorn's or A-team's gifts in Test space .. you could extrapolate forward .. b.c.

I wish EOSDIS let you record GIFs with various layer adjustments made. For example, I've adjusted the sea ice concentration layer in the following image to remove the artifacts that A-team discussed in post #48 of Test space.

Pragma

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Re: The 2019 melting season
« Reply #3132 on: July 02, 2019, 07:26:27 PM »
This is a problem that comes up over and over in science and in almost any discussion.  I think much can be clarified by people first defining the system they are analyzing.  So, if we define the system/area we are discussing as the CAB, then it becomes clear that spreading of ice in the CAB can be said to be dispersion, and ice spreading out the CAB can be said to be export.

Excellent point! In general, a frame of reference must be understood and agreed on.

If one person is talking in terms of the CAB and another is thinking of the entire arctic area, it's apples and oranges, and bound to lead to misunderstandings.

All that said, if someone say the XYZ sea is not melting this year but in fact it's being replenished from an adjacent area, it's just taking money of your left pocket and putting it in the right.

Context is everything. 

pearscot

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Re: The 2019 melting season
« Reply #3133 on: July 02, 2019, 07:39:27 PM »
I'm more confused than ever - I had thought this season, and from what I've read from the experts, that this year was certainly shaping up to be roughly in the top 5...but after looking at some of the overlays and comparisons it seems as though the pack is not as small (perhaps compact is a better word for it), as I had originally thought. I guess I will wait a bit and see how the melting unfolds the fist half of this month before assuming anything. I think that if the anomalously warm water continues to inundate the basin from the Bering Straight, bottom melt will be quite vigorous.
pls!

b_lumenkraft

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Re: The 2019 melting season
« Reply #3134 on: July 02, 2019, 07:46:24 PM »
I wish EOSDIS let you record GIFs with various layer adjustments made. For example, I've adjusted the sea ice concentration layer in the following image to remove the artifacts that A-team discussed in post #48 of Test space.

You can make screenshots and then load them up to https://ezgif.com in order to get a GIF.

RoxTheGeologist

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Re: The 2019 melting season
« Reply #3135 on: July 02, 2019, 07:58:51 PM »
I'm more confused than ever - I had thought this season, and from what I've read from the experts, that this year was certainly shaping up to be roughly in the top 5...but after looking at some of the overlays and comparisons it seems as though the pack is not as small (perhaps compact is a better word for it), as I had originally thought. I guess I will wait a bit and see how the melting unfolds the fist half of this month before assuming anything. I think that if the anomalously warm water continues to inundate the basin from the Bering Straight, bottom melt will be quite vigorous.

Extent and area have very poor correlation with the final minimum at this time of the year. You can see just looking at the graphs at how close all the years are during June and July. It's not going to be until August when we might see that all this worrying heat that's being applied to the ice finally melt it out. Think of warming a pan of ice from the base. When will the extent at the top finally disappear? Has enough heat been added to melt the whole thing out, or will there be a thin skin of ice left over the top? Nobody really knows until the whole complex system has had a chance to respond.

jdallen

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Re: The 2019 melting season
« Reply #3136 on: July 02, 2019, 07:59:31 PM »
It seems unusual to me the wind coming from south Asia to the Bering Strait. I don't see the normal jet stream. Instead, a flow south to north. It is coming a lot of heat to the Arctic, with this wind pattern?

https://earth.nullschool.net/#current/wind/isobaric/700hPa/orthographic=-212.00,61.11,316
That may be about the clearest most succinct example of the breakdown of the Hadley/Ferrell/Polar cell circulation I've seen yet.

Tropics straight to the Arctic.
This space for Rent.

pearscot

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Re: The 2019 melting season
« Reply #3137 on: July 02, 2019, 08:09:32 PM »
I'm more confused than ever - I had thought this season, and from what I've read from the experts, that this year was certainly shaping up to be roughly in the top 5...but after looking at some of the overlays and comparisons it seems as though the pack is not as small (perhaps compact is a better word for it), as I had originally thought. I guess I will wait a bit and see how the melting unfolds the fist half of this month before assuming anything. I think that if the anomalously warm water continues to inundate the basin from the Bering Straight, bottom melt will be quite vigorous.

Extent and area have very poor correlation with the final minimum at this time of the year. You can see just looking at the graphs at how close all the years are during June and July. It's not going to be until August when we might see that all this worrying heat that's being applied to the ice finally melt it out. Think of warming a pan of ice from the base. When will the extent at the top finally disappear? Has enough heat been added to melt the whole thing out, or will there be a thin skin of ice left over the top? Nobody really knows until the whole complex system has had a chance to respond.

Well put - that more or less confirms what I was thinking and why I will kinda hold my tongue until we can see the implications of what's been going on as of late.

I don't want to sound like I think that the ice in "good shape," rather I thought I would see more immediate ramifications of the weather immediately. THAT SAID, with the warm water coming in and the massive portion of shattered ice below 80 degrees, I think the melting momentum will cause a number of cascading effects.
pls!

Greenbelt

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Re: The 2019 melting season
« Reply #3138 on: July 02, 2019, 08:13:21 PM »
Yay more long-term forecasts that'll never be referenced again.
Hmmm. I try to check the weekly forecast each weekend. So far this season I think the 5-7 day forecasts have been remarkably accurate. We had advance notice of the large ESS high that torched the Laptev and ESS, advance of the low that traversed the arctic, advance of the recent Greenland-toward-ESS ridge, advance of the current rapid Fram export, and so on. For this week we can use the forecasts to watch out for a wind and heat event in the Barentz, a heat wave with jet stream to nearly the arctic in Alaska, and lower pressure in Siberia coasts mostly. The ensembles are still showing a classic dipole with high on the Canadian side and low pressure along Russia. Below is was the operational GFS for today from 7 days ago -- to my eyes the models have been predicting the main patterns quite accurately for many weeks now. After 5-7 days the operational models can generate some fanciful results to be disregarded, of course.  Nevertheless, I find tracking the forecasts a week ahead very useful for trying to learn what sorts of weather leads to better or worse melting conditions, which is a challenging question even for our experts I think. If Neven thinks the weather forecast discussion is clogging this main thread I think we could create a different thread for the looking ahead perhaps.

thejazzmarauder

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Re: The 2019 melting season
« Reply #3139 on: July 02, 2019, 08:22:17 PM »
Yay more long-term forecasts that'll never be referenced again.
Hmmm. I try to check the weekly forecast each weekend. So far this season I think the 5-7 day forecasts have been remarkably accurate. We had advance notice of the large ESS high that torched the Laptev and ESS, advance of the low that traversed the arctic, advance of the recent Greenland-toward-ESS ridge, advance of the current rapid Fram export, and so on. For this week we can use the forecasts to watch out for a wind and heat event in the Barentz, a heat wave with jet stream to nearly the arctic in Alaska, and lower pressure in Siberia coasts mostly. The ensembles are still showing a classic dipole with high on the Canadian side and low pressure along Russia. Below is was the operational GFS for today from 7 days ago -- to my eyes the models have been predicting the main patterns quite accurately for many weeks now. After 5-7 days the operational models can generate some fanciful results to be disregarded, of course.  Nevertheless, I find tracking the forecasts a week ahead very useful for trying to learn what sorts of weather leads to better or worse melting conditions, which is a challenging question even for our experts I think. If Neven thinks the weather forecast discussion is clogging this main thread I think we could create a different thread for the looking ahead perhaps.
Thanks for the reasoned reply, despite my being an ass. You're right that the D5 forecasts have been informative this year. My primary frustration was with the "fanciful" D8-D10 forecasts that kept getting posted with warnings of catastrophe, only for them to inevitably come down to earth by the D5 mark, while the next catastrophic D8-D10 forecast would get posted.

Sterks

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Re: The 2019 melting season
« Reply #3140 on: July 02, 2019, 09:06:58 PM »
Only one weather analysis in so many hours.
This must be relatively good news for the ice.

Rich

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Re: The 2019 melting season
« Reply #3141 on: July 02, 2019, 09:43:04 PM »
Only one weather analysis in so many hours.
This must be relatively good news for the ice.

Well. Tealight posted his June volume numbers. If I read it correctly, it looks like the Arctic lost 6-7M km3 of ice in the last 3 weeks of June.

Doesn't seem like good news.

aslan

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Re: The 2019 melting season
« Reply #3142 on: July 02, 2019, 09:49:07 PM »
Yay more long-term forecasts that'll never be referenced again.
Hmmm. I try to check the weekly forecast each weekend. So far this season I think the 5-7 day forecasts have been remarkably accurate. We had advance notice of the large ESS high that torched the Laptev and ESS, advance of the low that traversed the arctic, advance of the recent Greenland-toward-ESS ridge, advance of the current rapid Fram export, and so on. For this week we can use the forecasts to watch out for a wind and heat event in the Barentz, a heat wave with jet stream to nearly the arctic in Alaska, and lower pressure in Siberia coasts mostly. The ensembles are still showing a classic dipole with high on the Canadian side and low pressure along Russia. Below is was the operational GFS for today from 7 days ago -- to my eyes the models have been predicting the main patterns quite accurately for many weeks now. After 5-7 days the operational models can generate some fanciful results to be disregarded, of course.  Nevertheless, I find tracking the forecasts a week ahead very useful for trying to learn what sorts of weather leads to better or worse melting conditions, which is a challenging question even for our experts I think. If Neven thinks the weather forecast discussion is clogging this main thread I think we could create a different thread for the looking ahead perhaps.
Thanks for the reasoned reply, despite my being an ass. You're right that the D5 forecasts have been informative this year. My primary frustration was with the "fanciful" D8-D10 forecasts that kept getting posted with warnings of catastrophe, only for them to inevitably come down to earth by the D5 mark, while the next catastrophic D8-D10 forecast would get posted.

Forecast performances have been good lately, and IFS was awesome with many runs with an anomaly correlation above 0.8 at 192 h, wich again is not good because usualy the Euro is not the one who go into overdrive mode. But this June IFS was often even more crazy than GFS, and was correct. And to compare, a 192h forecast versus à 24h forecast, for tomorrow (July 3rd). Quite good, with ridges and troughs almost as expected... (And, not directly related to sea ice, but good for Barbara also, this speaks à lot)

And it is not because no one speaks of the forecast, that the forecast is not bad. And again the Euro guy is the worst,  wich is even worst because lately it has been quite correct being crazy while it is not in its "coding ADN" to be Phobos and Deimos.

Csnavywx

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Re: The 2019 melting season
« Reply #3143 on: July 02, 2019, 09:55:08 PM »
It's a bit mixed. Classical dipole breaks down a bit between D2-D3, shifts to a slightly off-center blocking pattern over the Atlantic and Pacific (with a small low/TPV in between) but then transitions back to a more classical dipole between D5-D6 on the ensembles. Cools off just a bit over part of the basin (back close to average for a couple of days, except for the central CAB) then back to the regularly scheduled blowtorch.

Might see a couple of slower days before it takes off again. 2012 went on a swan dive through mid-July, so we're likely to lose a bit of ground on it til mid-month, when it turned colder.

Csnavywx

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Re: The 2019 melting season
« Reply #3144 on: July 02, 2019, 09:57:19 PM »
The ensembles have been doing well with the pattern lately (through D7) and the Euro OP through D5, so there isn't much of an issue with posting out that far. It gets a bit sketchy by tau+192 though.

aslan

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Re: The 2019 melting season
« Reply #3145 on: July 02, 2019, 10:01:57 PM »
It's a bit mixed. Classical dipole breaks down a bit between D2-D3, shifts to a slightly off-center blocking pattern over the Atlantic and Pacific (with a small low/TPV in between) but then transitions back to a more classical dipole between D5-D6 on the ensembles. Cools off just a bit over part of the basin (back close to average for a couple of days, except for the central CAB) then back to the regularly scheduled blowtorch.

Might see a couple of slower days before it takes off again. 2012 went on a swan dive through mid-July, so we're likely to lose a bit of ground on it til mid-month, when it turned colder.

Yeah, it is not awefully bad either, juste bad or at least not quite good. Wich is to be put againt the fact that sea ice is in bad stage currently this said, so is more vulnerable to even "not so good" weather. I put the bias at D8 also to illustrate my point. Bias has lowered recently, but for GFS it is even a crash and he is now on the "not enough" side, wich is not its job.

bill kapra

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Re: The 2019 melting season
« Reply #3146 on: July 02, 2019, 11:47:05 PM »
I am at times amazed at the low quality English used by some of the native speakers on the forum

As a university professor in an English-speaking country, I can regretfully confirm that written English is weakening.

On the other hand, in a polyglot community like this one, just getting one’s meaning across is probably enough.

Michael Hauber

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Re: The 2019 melting season
« Reply #3147 on: July 03, 2019, 12:08:47 AM »

This is not something that needs to be 'balanced'. The implication is that things aren't really that bad, because look, 2012 was much worse. This is what annoys people and brings out the troll accusations. Because practically no one is saying - as of yet - that 2019 is looking much worse than 2012 in every respect. Things simply look very bad, that's all, but we don't know what the next weeks will bring.


But I'm not saying things are not as bad as 2012 in every aspect either.  I'm saying that in one aspect things aren't as bad as in 2012, and definitely acknowledge than in at least one other aspect - mid to late June heating this year is substantially worse.  Balance is to take note of both facts.  And then the hard part is how to put them together, one person might see the heat as being more important and think it likely that we are overall worse than 2012, and another might think dispersion is more important and think we are overall not as bad as 2012.  I'm leaning towards second, but its far from certain and people who think the heat is more important could easily be correct.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

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Re: The 2019 melting season
« Reply #3148 on: July 03, 2019, 12:42:44 AM »
Most of the discussion about dispersion is pointless because we don't have a direct measure of ice dispersion. The area vs extent figures include the effects of melt ponds. We know from published research that early melt ponds are important to extent drops later in the summer. Thus the conflation of the effects of dispersion and melt ponds is a major problem in our discussions of dispersion, as Neven gently noted. As someone trained in science, not diplomacy, I do not tend to be so gentle.

Available data sets, such as JAXA extent, show that this year is running neck and neck with 2012. However, the distribution of early melt ponds, open water and thick ice is quite different. The weather has been different.


Yes there is a serious issue that dispersion  cannot be put on an nice numerical basis.  Concentration values from AMSRE2 etc should in theory do this but cannot tell between reduced concentration due to melt ponds and reduced concentration due to floe separation.  However having looked at many images in MODIS I think it is obvious that there is a quite dramatic difference between different years in this aspect, and that this year is a lower dispersion year.  Maybe an algorithm such as I've seen previously which sorts through all MODIS images to find cloud free portions to get a weekly view combined with some pixel counting could put it on a numerical basis.  Failing that its a question of whether people trust my (and those who agree with me) subjective eyeball estimates, and whether anyone who disagrees can put together some convincing images to show otherwise. 

Jaxa images would suggest that 2012 was massively more disperse than 2019, however the sensors used are totally different, with a change midway through 2012.  Any comparisons based on Extent Vs Area need to take this into account with some data serious starting midway through 2012, and others patching togther the different sensors, or NSIDC still using the same sensor throughout (I think?), but one which is very sensitive to melt ponds.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

subgeometer

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Re: The 2019 melting season
« Reply #3149 on: July 03, 2019, 01:32:54 AM »
The dispersion used here means "dispersion of the pack in floes separating to each other". The examples we have today is Beaufort and somehow Kara. Caused by storms, usually.
Many examples you bring are called Trasport, or export, ect

Dispersal and Ice transport aren't mutually exclusive(any more than transport and compaction are). Recent Ice transport from the CAB into Beaufort, Barents and Greenland seas (all export)have seen their extent cease declining or go up while the CAB hasn't shown losses in return. That's why I used them as examples to counter what I saw as misrepresentation of data and the 'outlook'. Not to prove that "dispersion" was some really important Thing

Edit: There is a measure for dispersion: extent vs area as in the compactness charts Neven publishes(The problem is that they're too noisy for day to day comparison - the area and extent are on too coarse a grid maybe). But eg what's happening under the cloud north of the Chukchi sea is a lot more interesting right now, surely

« Last Edit: July 03, 2019, 01:48:04 AM by subgeometer »