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DavidR

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Re: The 2018 melting season
« Reply #3450 on: September 22, 2018, 03:52:44 PM »
The CAB and the Beaufort are striving to end the melt season, with rises over the past week. These recalcitrants have been the main reason the extent was not as low as some, like me, originally predicted. This was probably due to the cold winter in Alaska and Canada. How will the arctic will cope when Canada has a warm winter?
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oren

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Re: The 2018 melting season
« Reply #3452 on: September 22, 2018, 05:02:15 PM »
Very anomalous behavior all around. I think the end of the melting season shows the potential for low numbers this year had with slightly different weather.

uniquorn

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Re: The 2018 melting season
« Reply #3453 on: September 22, 2018, 05:08:26 PM »
Beaufort increase appears to be largely wind driven so far with gentle compaction further west(not shown)
Worldview, Beaufort sep15-21 (22 incomplete, 3MB)

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Re: The 2018 melting season
« Reply #3454 on: September 22, 2018, 08:37:17 PM »
Very anomalous behavior all around. I think the end of the melting season shows the potential for low numbers this year had with slightly different weather.
Exactly, the numbers of concentration, snow cover and extent in June invited to think (as has somehow been) on an 'average' melting season, in the mid of the 2010s, but actually it seems that a moderate push of extra heat may send next melting season, or any season, to the bottom. Funny that things are not different at all from previous years starting the refreezing (well it may actually be worse start) Will be interesting to watch.

uniquorn

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Re: The 2018 melting season
« Reply #3455 on: September 22, 2018, 09:12:27 PM »
Maybe someone with more knowledge of sea salinity/temperature will provide a more accurate scientific explanation but my very basic understanding so far is that the Atlantic ice front could be a long subduction zone where, in calm weather, warm salty water would normally sink beneath the cold fresh meltwater. Stormy weather running along the ice front will cause mixing and may delay freeze.

Mercator 0m salinity, sea temperature, anomaly and concentration for sep21.(400KB)
Very small windy wave update, sep22-oct1(1.2MB)

FishOutofWater

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Re: The 2018 melting season
« Reply #3456 on: September 22, 2018, 10:26:34 PM »
Something unusual is happening now but I haven't had the time to figure it out because I have been dealing with water & trees down from hurricane Florence. I'm doing well and my property is fine, but I have had a full plate. It was so good when the power came back on and I didin't have to fuel the generator to keep my sump pump going to keep my basement from filling with water.

There has been an unprecedented salinity increase at the 300m level on the Arctic shores of the CAA according to the Mercator Ocean model. I have been observing Mercator ocean for years but I have never seen anything like this.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20180701/20180918/2/4

Neven

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Re: The 2018 melting season
« Reply #3457 on: September 22, 2018, 10:46:06 PM »
Something unusual is happening now but I haven't had the time to figure it out because I have been dealing with water & trees down from hurricane Florence. I'm doing well and my property is fine, but I have had a full plate. It was so good when the power came back on and I didin't have to fuel the generator to keep my sump pump going to keep my basement from filling with water.

I didn't know you were in the storm's way, FOoW. Good to hear you didn't suffer (too much).

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There has been an unprecedented salinity increase at the 300m level on the Arctic shores of the CAA according to the Mercator Ocean model. I have been observing Mercator ocean for years but I have never seen anything like this.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20180701/20180918/2/4

I assume this is modeled, so couldn't it just be a glitch or a fluke?
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FishOutofWater

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Re: The 2018 melting season
« Reply #3458 on: September 22, 2018, 10:55:20 PM »
I was far enough inland and on high enough ground to be ok. Areas nearby near major rivers are flooding badly as we speak. The flood on major rivers is still cresting near the coast.

I don't think that this is merely a model result.  I think that the thin mobile ice near the northern shelf of the CAA could be seeing the effects of ice formation caused salinity increases combined with salinity increases caused by countercurrents at depth in some of the CAA's channels and the edge of the continental shelf of the CAA. Obviously, professional Arctic oceanographers are going to have to work out the physics of what's happening but I suspect that this is real.

Mercator doesn't show much going on at 30m and 100m but there is a rapid increase in salinity at the surface. This is expected as the melting season ends and the freezing season begins in the CAA but the increase in salinity is dramatic this September.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20180701/20180921/2/1
« Last Edit: September 22, 2018, 11:02:40 PM by FishOutofWater »

FishOutofWater

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Re: The 2018 melting season
« Reply #3459 on: September 22, 2018, 11:13:20 PM »
OMG I took a closer look. Warm, salty Pacific water is flowing up through the Bering strait on the Alaskan coast, then sinking into Barrow channel into the Arctic ocean at 30m and 100m. I don't know if this salinity is then reaching the CAA or if there's another source of CAA salinity but the warm current is a known phenomenon....but it's on steroids this year.

This is the warmest September in Alaska ever measured to date by a large margin and this certainly has something to do with it.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20180701/20180921/2/1

uniquorn

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Re: The 2018 melting season
« Reply #3460 on: September 23, 2018, 01:53:14 AM »
edit: mercator 300m salinity 20170601-20180922, every 5th day (2.5MB)
scale is not static
« Last Edit: September 23, 2018, 02:32:50 AM by uniquorn »

Rod

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Re: The 2018 melting season
« Reply #3461 on: September 23, 2018, 03:37:50 AM »
FOW, Please be safe!   Thank you for logging on and providing your thoughts.  I always look forward to seeing what you think is important to watch.  Thanks again, and stay safe!


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Re: The 2018 melting season
« Reply #3462 on: September 23, 2018, 05:23:43 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-22...

bbr2314

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Re: The 2018 melting season
« Reply #3463 on: September 23, 2018, 05:36:00 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-22...
Interesting to note model forecasts for the current typhoon. Instead of recurving into Japan right away, it looks like bits of energy break off and help reinforce the ridge over Bering / etc before the full recurve happens.

This could doom the ice in the ESS if modeling is correct, resulting in an absurdly late minimum for extent which we may have not yet reached.

bbr2314

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Re: The 2018 melting season
« Reply #3464 on: September 23, 2018, 06:40:58 AM »
Curious to see whether this gets worse or better as we approach (RE: AK...!)


Eco-Author

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Re: The 2018 melting season
« Reply #3465 on: September 23, 2018, 07:20:40 AM »
edit: mercator 300m salinity 20170601-20180922, every 5th day (2.5MB)
scale is not static

That last burst of salinity - Kelvin wave from saltier/lower depths... right at the time Beaufort melted out??
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bbr2314

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Re: The 2018 melting season
« Reply #3466 on: September 23, 2018, 09:01:10 AM »
Curious to see whether this gets worse or better as we approach (RE: AK...!)


EURO carbon copy... or worse?


Neven

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Re: The 2018 melting season
« Reply #3467 on: September 23, 2018, 10:05:16 AM »
JAXA jumped up by 28K today. I'm tempted to call it, given the current weather forecast (and I said I would close this thread as soon as the numbers would go 25K above the preliminary minimum), but I'll hold out until tomorrow. The isobars on this ECMWF forecast, well before Oct 1, are also quite impressive:
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Sterks

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Re: The 2018 melting season
« Reply #3468 on: September 23, 2018, 11:21:55 AM »
Ok I don't really care when you unlock the other thread but that forecast:
1 That's Sep 26.
2 That's Sep 26.
3 ...
I mean, Santa already started wrapping up stuff


Neven

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Re: The 2018 melting season
« Reply #3469 on: September 23, 2018, 11:35:50 AM »
Yes, but a couple of days of (big) increases wouldn't be amiss to pour that minimum in concrete, because a dipole that strong... I don't know, it could push the ice back and keep JAXA tracking close to the minimum.
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be cause

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Re: The 2018 melting season
« Reply #3470 on: September 23, 2018, 01:16:13 PM »
it does seem daft that melting and freezing cannot coexist on the forum when they do in the Arctic . It's been freezing for weeks north of Greenland while a little melt continues on the periphery and the ESS . DMI 80 temps are below where they were in late Feb ! b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

Neven

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Re: The 2018 melting season
« Reply #3471 on: September 23, 2018, 01:23:46 PM »
it does seem daft that melting and freezing cannot coexist on the forum when they do in the Arctic . It's been freezing for weeks north of Greenland while a little melt continues on the periphery and the ESS . DMI 80 temps are below where they were in late Feb ! b.c.

There are simply set dates for when the melting and freezing seasons officially begin, when the minimum/maximum get hit. Or do we have to keep this melting season open until March 2019, on the off chance that somewhere in the Arctic Circle there is one instance of melting due to exceptional circumstances?

Yes, the choice is arbitrary, but if we're consistent, there's no problem. Patience is a virtue.
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FishOutofWater

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Re: The 2018 melting season
« Reply #3472 on: September 23, 2018, 03:37:27 PM »
Yes, there could be upwelling of warmer, saltier waters from below the 300m level along the continental shelf margins. Large tidal effects could amplify Kelvin waves or waves internal to the Arctic basin. I just don't know enough oceanography to be able to give a decent analysis.

What surprised me was how rapidly the salinity increased at 300m over a large area.

Pmt111500

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Re: The 2018 melting season
« Reply #3473 on: September 23, 2018, 04:26:03 PM »
Yes, there could be upwelling of warmer, saltier waters from below the 300m level along the continental shelf margins. Large tidal effects could amplify Kelvin waves or waves internal to the Arctic basin. I just don't know enough oceanography to be able to give a decent analysis.

What surprised me was how rapidly the salinity increased at 300m over a large area.
Looks indeed the Arctic waters are slowly cut in half at the 300m depth by the Atlantic/Pacific inflow
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Niall Dollard

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Re: The 2018 melting season
« Reply #3474 on: September 23, 2018, 05:23:56 PM »

Curious to see whether this gets worse or better as we approach (RE: AK...!)


EURO carbon copy... or worse?


It is over a week away and looking at the surface pressure and temperature those two models are in big disagreement.

By that stage 18Z on 011018, ECMWF has HP centred in the Beaufort and much of the eastern Beaufort sub -6C and this extends across towards the ESS.

GFS on the other hand is much milder with a Canadian interior HP centred over Alberta and with LPs near the pole, there is a warm W or SW flow over Alaska coming right across the Beaufort. Huge part of the pacific side of the Arctic above zero. 

bbr2314

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Re: The 2018 melting season
« Reply #3475 on: September 23, 2018, 08:52:25 PM »

Curious to see whether this gets worse or better as we approach (RE: AK...!)


EURO carbon copy... or worse?


It is over a week away and looking at the surface pressure and temperature those two models are in big disagreement.

By that stage 18Z on 011018, ECMWF has HP centred in the Beaufort and much of the eastern Beaufort sub -6C and this extends across towards the ESS.

GFS on the other hand is much milder with a Canadian interior HP centred over Alberta and with LPs near the pole, there is a warm W or SW flow over Alaska coming right across the Beaufort. Huge part of the pacific side of the Arctic above zero.
I think the EURO is too cold at surface. 12z is even worse.




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Re: The 2018 melting season
« Reply #3476 on: September 23, 2018, 11:05:46 PM »
As far as the Arctic Seas in general are concerned, it looks like both SSTs and temperatures will tend to slow freezing overall. (Central Canada is not the entire Arctic)

GFS says Arctic temperature anomaly to increase from +1.4 to +2.4 celsius by Friday (and higher after that).
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Niall Dollard

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Re: The 2018 melting season
« Reply #3477 on: September 23, 2018, 11:40:22 PM »
Quote from: bbr2314
I think the EURO is too cold at surface. 12z is even worse.

In winter under anticyclonic conditions in the arctic, temperature inversions occur regularly. The euro is modelling an inversion along the north coast of Alaska at this time with surface temps of 0 C and +10 C at the 850 hPa level.

Opposite of what might be assumed but this report suggests that strong inversions are not good overall for the Arctic and help further Arctic amplification.

https://arstechnica.com/science/2011/10/a-cold-blanket-helps-the-arctic-warm-up/
« Last Edit: September 24, 2018, 12:02:05 AM by Niall Dollard »

slow wing

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Re: The 2018 melting season
« Reply #3478 on: September 24, 2018, 05:09:25 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-23...

Neven

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Re: The 2018 melting season
« Reply #3479 on: September 24, 2018, 05:35:59 AM »
I'm calling the (JAXA SIE) minimum.

Continue here.
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bbr2314

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Re: The 2018 melting season
« Reply #3480 on: September 24, 2018, 07:11:00 AM »
I'm calling the (JAXA SIE) minimum.

Continue here.
I think you are wrong...!

Neven

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Re: The 2018 melting season
« Reply #3481 on: September 24, 2018, 07:13:07 AM »
Let's hope so. Should be spectacular.  ;D
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Neven

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Re: The 2018 melting season
« Reply #3482 on: September 24, 2018, 07:22:49 AM »
Here are those isobars I mentioned in yesterday's post, that made me doubt whether I should call the minimum at just 28K above the preliminary minimum. But another 50K was added today, and I'm expecting some more tomorrow (unless some of that ESS ice flashes out of existence again). Whether it will be enough to offset the compacting power of those isobars, remains to be seen. An exciting end to the melting it is.
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El Cid

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Re: The 2018 melting season
« Reply #3483 on: September 24, 2018, 08:03:55 AM »
An exciting end to the melting it is.

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Re: The 2018 melting season
« Reply #3484 on: September 25, 2018, 03:15:12 PM »
It's not over yet, 2018 extent is still flatlining. It's now lower for the day of year than any year since 2000 except 07 and 12.
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Re: The 2018 melting season
« Reply #3485 on: September 26, 2018, 12:20:20 AM »
It's not over yet, 2018 extent is still flatlining. It's now lower for the day of year than any year since 2000 except 07 and 12.

That's actually a very interesting little bit of fact.
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litesong

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Re: The 2018 melting season
« Reply #3486 on: September 27, 2018, 12:37:54 AM »
Does the sun just rotate around the edge of the horizon in the arctic for the 24 hours of sunlight?

No, it doesn't.
If you use the tool linked by jacksmith4tx you can that e.g. at Barrow, sun has an elevation of around 45 degrees at the end of June.

SunEarthTools.com
https://www.sunearthtools.com/index.php

At Barrow noontime at the beginning of summer, the sun is at an elevation of ~ 42arcdeg above the horizon. At Barrow "midnight" at the beginning of summer, the sun is ~ 4 & 2/3rds arcdegs above the horizon. I wasn't using jacksmith.
« Last Edit: September 27, 2018, 04:24:13 AM by litesong »

vox_mundi

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Re: The 2018 melting season
« Reply #3487 on: September 27, 2018, 07:50:07 PM »
NSIDC Calls It: 2018 Arctic Sea Ice Minimum Extent Tied for Sixth Lowest on Record
https://nsidc.org/arcticseaicenews/2018/09/arctic-sea-ice-extent-arrives-at-its-minimum/

Quote
Arctic sea ice likely reached its 2018 lowest extent on Sept. 19 and again on Sept. 23, according to NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. Analysis of satellite data by NSIDC and NASA showed that, at 1.77 million square miles (4.59 million square kilometers), 2018 effectively tied with 2008 and 2010 for the sixth lowest summertime minimum extent in the satellite record.

"This year's minimum is relatively high compared to the record low extent we saw in 2012, but it is still low compared to what it used to be in the 1970s, 1980s and even the 1990s," said Claire Parkinson, a climate change senior scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Parkinson and her colleague Nick DiGirolamo calculated that, since the late 1970s, the Arctic sea ice extent has shrunk on average about 21,000 square miles (54,000 square kilometers) with each passing year. That is equivalent to losing a chunk of sea ice the size of Maryland and New Jersey combined every year for the past four decades.



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Re: The 2018 melting season
« Reply #3488 on: September 27, 2018, 09:36:34 PM »
Frigging outstanding video to end the season.
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