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Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #1450 on: March 19, 2018, 09:51:20 PM »
Just as well Neven and El Cid know what to do - 'cos I ain't got a clue. I'm still struggling with the basics. - such as this. The DMI 80+ North temperature graph has gone below the green line for the first time since 2014. Not only that, but it is a magnificent temperature drop of about 18 degrees kelvin in about two weeks almost without any pause and liable to persist at least until Thursday or Friday.

Technically, the temp has gone below the green line about every spring and summer.  That is: warm winters, cold summers.

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #1451 on: March 19, 2018, 10:04:53 PM »
Just as well Neven and El Cid know what to do - 'cos I ain't got a clue. I'm still struggling with the basics. - such as this. The DMI 80+ North temperature graph has gone below the green line for the first time since 2014. Not only that, but it is a magnificent temperature drop of about 18 degrees kelvin in about two weeks almost without any pause and liable to persist at least until Thursday or Friday.

Technically, the temp has gone below the green line about every spring and summer.  That is: warm winters, cold summers.

Huh, clever clogs - you knew I was talking about the winter bit. Maybe summer has come early (i.e. the cold season).
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Neven

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Re: The 2017/2018 freezing season
« Reply #1452 on: March 19, 2018, 10:13:03 PM »
Hmmm, I thought I said the green line wouldn't be crossed. Why doesn't the Arctic ever listen to me?  ;)

This is one of the craziest things I have seen on the DMI 80N temp graph. It doesn't get much crazier really, except perhaps for a couple of spikes during summer (which we might see in the near future).
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Archimid

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Re: The 2017/2018 freezing season
« Reply #1453 on: March 19, 2018, 10:31:49 PM »
The N80 temperatures graph is very interesting. In an attempt to visualize the anomalies of N80 in a time series I measured the pixels under the curve of N80 using Gimp. I counted everything between the curve and the baseline as a positive anomaly and when the curve went under the baseline I counted everything in between as a negative anomaly and added it all up. For convenience and as a way to isolate the Arctic winter, I measured from day 0 to day 100 and from day 300 to the end. 2018 is represented until day 78.

I only did it until 2011 because before that the graph changes. If I figure a way to normalize them I'll post longer anomalies.
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Gray-Wolf

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Re: The 2017/2018 freezing season
« Reply #1454 on: March 19, 2018, 10:34:26 PM »
The thing is we will now have a myriad of deniers  pointing to the remarkable event of DMI 80 N hitting average!!

Are things so whacked out that 'average' is the new remarkable!
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Pmt111500

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Re: The 2017/2018 freezing season
« Reply #1455 on: March 20, 2018, 02:19:26 AM »
The thing is we will now have a myriad of deniers  pointing to the remarkable event of DMI 80 N hitting average!!

Are things so whacked out that 'average' is the new remarkable!
could we f.e. say it took this long a time for arctic to cool down to normal temperatures?
« Last Edit: March 20, 2018, 02:39:15 AM by Pmt111500 »
Cooling the outside by heat pump.

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #1456 on: March 20, 2018, 03:20:29 AM »
Blame the very weird March weather on the sudden stratospheric warming. The NE U.S. has been slammed with snowstorms. New York City and suburbs is in the bullseye Wednesday. There's been a massive amount of sinking stratospheric air over North America.

The warm areas at 150mb - the base of the stratosphere in the temperate NH in March are areas of stratospheric subsidence. The relative warmth has been caused by subsidence driven compressional heating after the SSW. This subsidence is associated with a cold troposphere below because the polar jet stream gets driven southwards in this situation.

This pattern has allowed the 80ºN to the pole region to cool to seasonal norms.

There continues to be a strong Rossby wave number 1 pattern with warmth over temperate  central Asia and the temperate west Pacific. The west Pacific has warmed significantly over the past week.

Michael Hauber

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Re: The 2017/2018 freezing season
« Reply #1457 on: March 20, 2018, 03:35:02 AM »
The thing is we will now have a myriad of deniers  pointing to the remarkable event of DMI 80 N hitting average!!

Are things so whacked out that 'average' is the new remarkable!

There was a week or two around this time of year in 1958 when the DMI was above average.  Pretty sure at least one of the years near the start of the record would have had an above average value on this date.

The last time we saw DMI below average during the colder half of the year was in Dec 2015.  Was an annual occurrence before then.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Coffee Drinker

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Re: The 2017/2018 freezing season
« Reply #1458 on: March 20, 2018, 04:26:15 AM »
The thing is we will now have a myriad of deniers  pointing to the remarkable event of DMI 80 N hitting average!!

Are things so whacked out that 'average' is the new remarkable!

Average compared to 1950 to 2000. We don't have that climate anymore. So yes, its remarkable.

romett1

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Re: The 2017/2018 freezing season
« Reply #1459 on: March 20, 2018, 09:14:22 AM »
There should be spike upwards soon on this DMI north of 80 chart - cyclone from the Bering Sea brings warm winds again all the way towards North Pole over the weekend. Comparison - March 20 vs March 24. Images: http://www.karstenhaustein.com/climate.php

Dave C

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Re: The 2017/2018 freezing season
« Reply #1460 on: March 20, 2018, 11:37:18 AM »
I believe this is the first time DMI 80N has touched climatology while the temperature was below 245K since late 2015.  I will note that the climate curve has left the bottom and is heading toward Summer melt in the High Arctic.  (The temp did go below 245 once, but it was in the dead of winter, and did not reach to climatologic average.)

I went back and looked at the last 20 years of graphs. Winter seems to have some relationship to freezing level. But the April-September numbers seem to tell us nothing about the actual level of melt going on. Is this the impression others see?

Juan C. García

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2018 Melting Season
« Reply #1461 on: March 20, 2018, 11:38:02 AM »
Oopsss!!! What happen!!!  :o

"The 2017/2018 freezing season" became suddenly the "2018 Melting Season"  ::)  ;D

Honestly, I am surprised to see the huge JAXA drops in just two days and the warm weather entering from the Bering Strait.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Gray-Wolf

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Re: The 2017/2018 freezing season
« Reply #1462 on: March 20, 2018, 01:48:25 PM »
A lot of the recent gains were no more than the ice 'reorganising itself' and by so doing triggering the 15% or more trigger?

The 'Flow and go' we see in Bering/Okhotsk/Baffin and the Atlantic side ( Kara/Barentsz ) all saw floes 'stretched out' and fragmented as they flowed south. Ice will have skimmed over where the ice came from but the front edges of the 'flow and go' ice are now entering hostile waters ( milky swirls in the waters around the ice edge) and so are reducing. Just as tripping over 15% can bring a whole square into being so slipping below 15% will do the opposite ( and blink out).

in my early seasons of ice watching I got fed up of folk telling me the 'ice is still growing' when , in fact, the ice edge was fragmenting and ice was being exported to more southern waters ( i.e. off to die).

This season has been a bit like that in it's ending with 'floatoff' from shores and out into busier waters ( allowing for breakup ) and drift south.

Bye Bye freezing season!
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #1463 on: March 20, 2018, 03:45:16 PM »
A large area of ice flashed out of view in the last storm in the Okhotsk sea. There's one more push of cold air there, but it's a battle between the slight warmth of ocean mixed up from below with the cold air above. Since the cold air isn't as cold there in late March and the ocean has a huge heat capacity we're coming to the point where the ocean and the sun kill the ice. The thing is, with the very thin ice in the peripheral seas, the ice can flash out in hours in one storm. Neven may have won the bet on the max. Whatever, we're not talking about a large mass of ice melting out in the peripheral seas to make that sudden extent drop. We're talking about thin ice going under the detection limits after a storm passed by.

More importantly, the displacement of the stratospheric polar vortex towards Siberia favors continued flow at all levels of the atmosphere over the Arctic ocean from the Pacific towards the Atlantic. This pattern will increase ice export through the Fram and will favor ice loss in the Bering and Beaufort seas.
« Last Edit: March 20, 2018, 04:13:29 PM by FishOutofWater »

jdallen

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Re: The 2017/2018 freezing season
« Reply #1464 on: March 20, 2018, 04:29:31 PM »
<snippage>
The thing is, with the very thin ice in the peripheral seas, the ice can flash out in hours in one storm. Neven may have won the bet on the max. Whatever, we're not talking about a large mass of ice melting out in the peripheral seas to make that sudden extent drop. We're talking about thin ice going under the detection limits after a storm passed by.

More importantly, the displacement of the stratospheric polar vortex towards Siberia favors continued flow at all levels of the atmosphere over the Arctic ocean from the Pacific towards the Atlantic. This pattern will increase ice export through the Fram and will favor ice loss in the Bering and Beaufort seas.
I expect the coming cyclone hitting the Bering may very dramatically roll back the last 10 days or so of extent increases there.  The  necessary heat is already there.  The storm will push out the cold and stir things up.  My thumbnail guess is that the oldest of that new ice probably hasn't had the chance to thicken past 50CM, *if* *that*, and will retreat just as fast if not faster.  I anticipate the Bering being pretty much clear by April 1, and serious inroads being made into the Chukchi shortly after if not sooner.
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #1465 on: March 20, 2018, 04:30:38 PM »
A lot of the recent gains were no more than the ice 'reorganising itself' and by so doing triggering the 15% or more trigger?

The 'Flow and go' we see in Bering/Okhotsk/Baffin and the Atlantic side ( Kara/Barentsz ) all saw floes 'stretched out' and fragmented as they flowed south. Ice will have skimmed over where the ice came from but the front edges of the 'flow and go' ice are now entering hostile waters ( milky swirls in the waters around the ice edge) and so are reducing. Just as tripping over 15% can bring a whole square into being so slipping below 15% will do the opposite ( and blink out).

Bye Bye freezing season!

Which could mean that strong Southerly winds for five days from the N. Pacific through the Bering Sea and the Bering Strait into the Chukchi, plus above zero temperatures reaching as far as into the Chukchi for at least a couple of days could cause a lot of blinking.
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Gray-Wolf

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Re: The 2017/2018 freezing season
« Reply #1466 on: March 20, 2018, 04:31:35 PM »
If you have a look at Okhotsk you can see the main body of ice well off shore and only a thin skim filling where it floated off from. This will 'blink out' the first warmth/waves it encounters but the same is true for the late formed infill over the Atlantic side of the basin that formed behind the 'flow and go' ice that is heading south in Barentsz?

So we have some 'good ice' floating to its destruction but also the ice that covered over its place of origin leaving two lots of 'easy ice' to lose over the next 6 weeks?

Then we'll have the rest of the central pack to have a look at and just how mangled it has been over winter? Just how quickly will we see it 'relaxing out' once we are in full sun up there?

I'm also noting how the high northern blocking in the Atlantic has kept Barentsz/Kara quite cloud free this past 2 weeks? I hope this isn't a sign of things to come?
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #1467 on: March 20, 2018, 04:32:31 PM »
There's been a huge atmospheric ridge south of the Aleutians for the past 30 days. The ridge is caused by intense subsidence that is associated with both La Niña and the stratospheric polar vortex splitting event. In early to mid February there was the strongest west Pacific Madden Julian Oscillation event since the MJO has been tracked by meteorologists. What goes up must come down. The intense convection that took warm air up over the tropical west Pacific has come down over the temperate north Pacific making the huge high at 500mb. 500mb is about half the surface pressure so 500mb surface is very helpful for analyzing persistent weather patterns. The map below clearly shows enhanced subsidence south of the Aleutians over the past 30 days.

This subsidence is heating the north Pacific because of fewer clouds, warmer air and more surface insolation than normal. The warm water will supply excess water vapor to the Arctic in the coming months, speeding up the loss of sea ice volume on the Pacific side of the Arctic.
« Last Edit: March 20, 2018, 04:37:34 PM by FishOutofWater »

Stephan

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Re: The 2017/2018 freezing season
« Reply #1468 on: March 20, 2018, 07:22:33 PM »
The N80 temperatures graph is very interesting. In an attempt to visualize the anomalies of N80 in a time series I measured the pixels under the curve of N80 using Gimp. I counted everything between the curve and the baseline as a positive anomaly and when the curve went under the baseline I counted everything in between as a negative anomaly and added it all up. For convenience and as a way to isolate the Arctic winter, I measured from day 0 to day 100 and from day 300 to the end. 2018 is represented until day 78.

I only did it until 2011 because before that the graph changes. If I figure a way to normalize them I'll post longer anomalies.
Thank you for collecting the data and computing the the temperature difference. What is very obvious is that early winter of 2016/17 and also parts of 2017 were abnormally warm. The temperature difference for 2018 has now reduced a little bit in the last two weeks, but it is of course still (much) higher than in the years 2013 or 2014. So the drop of the "DMI 80" temperature below the long-term average will be a short exception, see the other posts that forecast a soon warming on the Pacific side of the Arctic Ocean.

NeilT

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Re: The 2017/2018 freezing season
« Reply #1469 on: March 20, 2018, 08:11:30 PM »
How low will you go?

If recent history is anything to go by, not as low as the green line.  ;)  :'(



You see that's the problem with predicting the Arctic....

It is, however, essentially, solar minimum.
Being right too soon is socially unacceptable.

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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #1470 on: March 20, 2018, 08:30:42 PM »
How low will you go?

If recent history is anything to go by, not as low as the green line.  ;)  :'(
You see that's the problem with predicting the Arctic....

It is, however, essentially, solar minimum.
How low will you go? Lower
The revenge of the Equinox
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Lord M Vader

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Re: The 2017/2018 freezing season
« Reply #1471 on: March 20, 2018, 09:27:23 PM »
Well, it has happened before according to the DMI. Eyeballing the years fro 1958-2017 reveals that two winters, 1984 and 1985, for certain saw the lowest temps around or after the solstice.

The two winters 1970 and 2006 both had their coldest periods late in the season but clearly before the solstice.

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #1472 on: March 20, 2018, 09:49:50 PM »
Well, it has happened before according to the DMI. Eyeballing the years fro 1958-2017 reveals that two winters, 1984 and 1985, for certain saw the lowest temps around or after the solstice.

The two winters 1970 and 2006 both had their coldest periods late in the season but clearly before the solstice.
So nowt like it for 33 years ?  Climate change ?  Just an oddity ?
Always more questions.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #1473 on: March 20, 2018, 09:57:39 PM »
Quote
forecast a warming soon on the Pacific side of the Arctic Ocean.
Maybe so but those beautiful "cloud streets" in the Barents (associated with cold winds of a meandering central anti-cyclonic high) will continue out to March 25th and beyond, per GFS.

Twitter can confuse these with with blowing Antarctic ice needles or katabatic Greenland winds but Zach notes correctly today these are parallel bands of cumulus clouds that form as cold winds from the north blow off the ice edge onto warmer ocean waters.

OK, but why now, why cumulus mediocris, and what causes the street banding? 

The temperature differential between cold air blowing off the ice and the sea surface water, either open leads or more commonly beyond the ice edge, can easily exceed 20ºC in March. Thermal columns of moist heated air rise off the sea surface until they hit a denser warmer lid of air (provided a temperature inversion is present).

As the thermals are advected downwind and sink or rise according to ambient density differences, they form parallel pairs of counter-rotating cylinders of air. On the upper surface of rising air, water vapor cools and condenses into flat-bottomed, fluffy-topped clouds (ie cumulus: https://en.wikipedia.org/wiki/Cumulus_cloud). On the downdrafts, condensates evaporate giving clear skies on the sides of the clouds, the banding.

Surprisingly, the alignment of vortices alone does not reliably indicate wind direction. Stably stratified environments have lines 30° off CCW to the left; only an unstably stratified (ie convective) situation has bands parallel to mean wind.

Cloud streets are technically called horizontal convective rolls. The most favorable conditions for them occur when the lowermost layer of air is unstable, driven by a moderate wind and capped by a stable inversion, a common situation when upper air is subsiding, such as under recently prevailing anticyclonic conditions.

https://en.wikipedia.org/wiki/Horizontal_convective_rolls turbulent momentum flux in PBL

Quote
Cloud Streets over sea can be seen during synoptic scale outbreaks of cold, dry air from continents over a neighboring relatively warm ocean. This flow often occurs behind a Cold front. As the cold air leaves the land or ice surface it is modified by vertical transfer of heat and moisture from the underlying water surface. An inversion will be formed the base of which rises with the distance from shore. The formation of the inversion is, in many cases, stimulated by NVA and subsequent sinking motion in the stream upwind of the 500 hPa trough-axis. The transformation of the air mass eventually leads to the formation of clouds which, under certain circumstances, take the form of Cloud Streets, and develop roughly parallel to the wind direction. Further downwind from the outbreak, the unstable layer becomes deeper, the flow becomes more cyclonic and the streets develop into three-dimensional open cells. Near the upper-trough the convection is enhanced by PVA, resulting in the formation of enhanced cumulus and comma.

http://www.zamg.ac.at/docu/Manual/SatManu/main.htm?/docu/Manual/SatManu/CMs/ClStr/backgr.htm

North Atlantic islands like Jan Mayen disrupt the flow of the wind and create spiral eddies patterns in the cloud streets called von Karman vortex streets. These have not been seen this March with SZ or FJL islands, presumably because they are less disruptive to air flow.

http://en.es-static.us/upl/2013/05/von-karman-vortex-clouds-nasa-24feb2009-540.jpg

We've also been seeing "comma clouds" which are vortices or mesoscale eddies that occur when warm humid air wraps counterclockwise around the cold air, forming clouds as these air masses rise. Comma clouds are a leading indicator of a small-scale low-pressure system forming. In the absence of an inversion, polar lows can grow into strong but small-scale cyclones. March is a big month for both cloud streets and polar lows.

http://polarportal.dk/fileadmin/polarportal/sea/Map_IST_LA_EN_20180319.png

https://earth.nullschool.net/#2018/03/[cal]/1200Z/wind/isobaric/1000hPa/overlay=off/orthographic=-45.00,82,1250/loc=2.5,83.00

https://earthobservatory.nasa.gov/IOTD/view.php?id=87749 nice example

Quote
New areas of polar lows over the Arctic as a result of the decrease in sea ice extent
E Zabolotskikh et al.
https://link.springer.com/article/10.1134/S0001433815090200

Mesocyclones can arise when new areas of open water appear. Polar lows don’t form over sea ice, so as the sea ice retreats, new ocean areas with relatively warm water are exposed to cold air outbreaks, the favored environment for polar low formation, the Kara Sea being a prime example. Zahn and von Storch 2013) predict the decrease in both number of polar lows in the Arctic and their
intensity in the future due to the faster air temperature increase relative to water temperature and therefore higher stability of the boundary atmospheric layer.

Street clouds represent very cold and dry air from above the sea ice transported out over the open ocean, ie cold air outbreaks. It's not uncommon to see 3-4 polar lows over the Barents Sea in comma cloud cyclone category. These are baroclinic, meaning the low near the surface is linked to a trough higher up in the atmosphere, with these not located on top of each other. This vertical structure displacement allows the two lows to work together and to strengthen each other.

Most polar lows start out as baroclinic but many develop a warm core and go barotropic, meaning the and near-surface and lows aloft are locked in phase and no longer help each other grow. For the polar low to intensify at this stage, it needs to get its energy from the warm ocean surface, as with tropical cyclones (hurricanes) energetics. However the Arctic Ocean surface is far too cold to admit  arctic hurricanes. (Adapted from https://polarlows.wordpress.com/author/erikwkolstad/)
« Last Edit: March 20, 2018, 10:36:03 PM by A-Team »

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #1474 on: March 20, 2018, 10:53:46 PM »
That last image clearly shows how large the area of relatively thin ice that has migrated into the CAB from the Kara over the winter. Is this typical or has there been more pronounced migration this year?

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #1475 on: March 21, 2018, 12:58:32 AM »
Worldview images taken around the equinox of Barents/Kara (give or take a day or two in order to get views with least cloud) for the years 2018 back to 2015.

Juan C. García

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Re: The 2017/2018 freezing season
« Reply #1476 on: March 21, 2018, 04:59:56 AM »
On March 20th, the JAXA 2018 has 13,713,053 km2, a daily drop of -48,229 km2.
So now, the difference between the March 17th max and today is of -178,137 km2
The melt season is officially starting.

Good bye, 2017/2018 freezing season!   :'(     ;D
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Lord M Vader

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Re: The 2017/2018 freezing season
« Reply #1477 on: March 21, 2018, 08:05:04 AM »
Well, indeed is the freezing season over although the "thickening" season isn't over yet. If the EC forecast is correct, the melting season might start with a loud bang as a decent transport through Fram strait and other channels should be resilient during the next 10 days. Let's see how it pans out!

The Governor should open up the melting season thread as soon as he is awake :D

Neven

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Re: The 2017/2018 freezing season
« Reply #1478 on: March 21, 2018, 08:21:34 AM »
I'm awake.  :)

The 2018 melting season thread is open for business.

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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #1479 on: March 21, 2018, 04:05:13 PM »
Great forecast in the poll, Neven. I'll see you in the melting threads.

Before everyone moves on from this freezing season discussion, I strongly recommend taking a look at this excellent paper on polar lows that A-Team led me to. It updates the science of polar lows and it's written lucidly. I wish that Americans could write papers in English as well as this Norwegian does.

http://nora.nerc.ac.uk/id/eprint/513995/1/Kolstad_et_al-2016-Journal_of_Geophysical_Research__Atmospheres.pdf

His blog is both beautiful and informative. https://polarlows.wordpress.com/author/erikwkolstad/

Thanks, A-Team, for introducing me to the work of Erik W. Kolstad.


Hautbois

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Re: The 2017/2018 freezing season
« Reply #1480 on: March 21, 2018, 09:58:57 PM »
Cross posting from 'on what date?'


gerontocrat

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Re: The 2017/2018 freezing season
« Reply #1481 on: March 21, 2018, 10:07:59 PM »
Cross posting from 'on what date?'

Another graph goes into hibernation?
Got something similar for September? I hope so
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #1482 on: March 21, 2018, 10:19:14 PM »
Cross posting from 'on what date?'
After 2011, it is all 15, 16, 17, 18 at the bottom....What is the timeline for ENSO?  Every 3 to 7 years?  Couple more years (or blue ocean) and I think we can declare a collapse.

Hautbois

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Re: The 2017/2018 freezing season
« Reply #1483 on: March 22, 2018, 01:04:50 AM »
Cross posting from 'on what date?'

Another graph goes into hibernation?
Got something similar for September? I hope so


Indeed, I posted a 'descent to the min' equivalent a couple of times last year. I'll dust it off on August 1st.