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Messages - johnm33

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1
 You need to zoom in on this gif from hycom to see the impressive outburst of freshwater from Jakobshavn around the 11th
Looks like the granular ice in the channel is being finely ground, from sentinel


2
The output of the glacier continues, a detail from the latest Polarview


 It may be that sufficient ice is flowing down the main channel/falling down from the heights of the ice sheet that we are witnessing the squeezing out of the deep waters present, it seems a lttle early for melt water to be flooding out, or it could be that saline water has kept last seaons meltwater liquid and possibly eased the flow properties of the granular ice in the channel. If the latter is true then as the ice flow above is eased by melt we could witness a very abrupt advance of the calving front which could only be sustained by a widespread local slump of the ice sheet. On the other hand if we are witnessing the consolidation of the ice in the main channel then we may see little change over the next few years, just small advances, calvings and retreats.

3
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 02, 2019, 09:58:21 PM »
It would be interesting to know the timings of when warmer or more turbulent waters arrive below that 'fishing hole'.

4
An interesting image from polarview today, it looks like there's been a serious flood of basal water break out from beneath the southern branch, which has advanced and calved and this before a big seasonal tide at the weekend. The second collapse feature on the northeast face of the southern branch, just before the bend, is not evident in the image so I await a clear day on sentinel.
  Coincident with this the northern glacier, not branch, which had a 'fan' calving this winter has begun to move too.

5
Arctic sea ice / Re: "Stupid" Questions :o
« on: April 14, 2019, 11:15:58 PM »
I pretty much agree with that, how many images and over what period crossed my mind, but yes if the water begins to fall/drop into a trough it will organise itself according to it's rotational potential and once established, i imagine, like a tornado it will twist turn and move according to the medium it's passing through. Atlantic waters reaching this far north will have acquired quite a lot of torque since passing 600N, or if you will may not yet have lost the intrinsic torque of being about 1/2 the planets radius away from the axis of rotation [in much the same plane], which will be expressed as it's forced into a coherent stream.

6
Arctic sea ice / Re: "Stupid" Questions :o
« on: April 12, 2019, 10:47:11 AM »
It's very close to the head of Santa Anna basin trough so maybe the waters from Kara are dropping into the basin trough hereabouts?

7
Looking back this is why I formed the view that seawater penetration once past the first cill, at 5K, was more or less unstoppable, the more saline water will always pass over the inner cills and move upstream before it becomes dilute enough to move back towards Disko. The recorded calvings of giant icebergs I suspect are the result of the ice in the deepest part of the trough being floated and breaking through the weight of ice above freeing that space for seawater penetration. There have been enough of these giant icebergs to convince me that some of them have come from inland of sills#1 and #2 from the first link. These blocks of coherent ice have been replace by ice moving downstream, so now in place of a smooth ice surface to grind over there is a melange of broken ice pressed to the depths of the chasms by the weight of the ice above it suffused with saline water.
 Were any cryopegs present beneath these giants? are there more upstream? as would seem probable if they froze from the top down.
 Tidal forces act on landmasses as well as oceans so they will act on ice bodies too the more fluid the ice the greater the potential effect, so it's not just a matter of the tidal waters penetrating and lifting the ice, and all I'm suggesting here is that the calvings and advances occur close to the extreme tidal range at new/full moons. The ice height of 200m ft. above the waters surface means there can't be any actual lifting from tidal penetration but increased melt is another matter.
See this comment too, https://forum.arctic-sea-ice.net/index.php/topic,154.msg56298.html#msg56298
So I'm still of the opinion that the cool saline water in Disko is discharge from the glacier mixed with tidal and possibly cryopeg waters. Is it correct to call it a grounding line if the ice is a composite of melange and seawater? if so ok.

8
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: April 09, 2019, 02:59:36 PM »
A tidal wave has another meaning altogether, usually nothing to do with tides, I use the term surge because the tides high-high or low-low are about 12.5 hours apart so low-high 6+ so more like a really slow swell. The tides at the Lincoln end of Nares have some peculiar resonances too iirc, and I've yet to understand them. This links to Alert and there's a tide station map for others https://www.tide-forecast.com/locations/Alert-Nunavut/tides/latest
and more here

9
Arctic sea ice / Re: The 2019 melting season
« on: April 08, 2019, 11:12:26 AM »
"speeding up the whole darned thing" There's constant pressure on the Atl. side trying to force water in to the Arctic, if Nares, and the CAA generally, blocks the surface flow then the fractions below the surface have to force their way out which calls for far more energy. If Nares is flowing freely then the speed of surface waters towards Greenland increases and more flows through Fram too dragging the ice with it. Then more Atl. water flows in and the most energetic fraction moves towards Kara the nursery for thick ice.

10
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: April 02, 2019, 04:36:06 PM »
"From the north and northwest", the Beaufort gyre has met the incoming Atl. water in Chukchi/ESS the two counter rotations are forming a thicker band of ice that heads for Ellesmere, some shifts towards Fram some exits Nares some recycles around the B. gyre. Look back at one of unicorns ascat animations.
Right now there's a powerful high in the west of Beaufort and a deep low in Labrador, we've also had persistent 4? days of wind blowing ice towards Banks Is. That implies some Pacific waters will surge in through the strait, so all three exits are busy exporting the freshwater lens and Nares may not settle til' after the new moon.

11
"Tracing the origin of the cold waters in front of Jakobshavn was a challenge," explained Ian Fenty of JPL, a co-author of the study. "There are enough observations to see the cooling but not really enough to figure out where it came from."
Not that I'd bet on my guess against NASA's but I have been expecting saline waters to emerge from beneath the ice for quite some time, I have long suspected that sea water has penetrated as far as the round feature upstream, more or less central in this image from Polar View. Also that it's very likely that some salt deposits will sit in the deepest troughs/valleys just as it does beneath ice yedoma elsewhere, if there's any merit in my idea then the salt will continue to dissolve and the resultant slush will continue to lubricate the basal ice's passage. We'll see.
added- Link to supplemental pdf with salinity/temp charts etc.

12
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: March 24, 2019, 01:17:57 PM »
Looking at 156/7/8 animations some of the things I'm suggesting already seem to be there, just couldn't see them til' I looked for them. What I was particularly interested in was the increasing Atlantification of the shelf waters in Laptev through ESS, it appears the saline Atlantic waters are stopping the Siberian freshwater from entering the Arctic in it's accustomed way and that it is only entering much further east, where the inflow from Bering is being forced west and mixes with it. Thus the 'ridge' of thick ice being formed further east one could say at the confluence of the gyre and the incoming Atlantic stream. That may be responsible for the increasing depth of the 'Pacific' layer.
 The more or less random pulses of Atlantic waters coming through Fram on their way to Nares is there to be seen too, as is the flow which is likely generating the gyres which are dropping into Beaufort and Atlantifying it's basal waters.
I don't know if the Davis Strait array is functioning or if/when the data is accessible, I guess an alternative would be a record of expected and actual tides from somewhere on Baffin Island to give some clue about how much fresh-water is escaping. Higher low tides = more imho.
I'm beginning to think I must have upset a Chinaman, interesting times.

13
No calving to speak of but about 1km advance polarview



14
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 01, 2019, 12:42:58 PM »
There's a sheer line in the compressive strength of the ice, it points towards Prince Patrick is. but may be seen as terminating in Mclure or by Banks is. I wondered if it would actually show up on the ice, there's a diagonal line of leads opening across the polarview image which seem a close match.
 

I'm guessing the parallel waves[?] are tidal surges coming in from the Pacific.

15
Some recent calving, detail from polarview
There's also a feature midstream at the bottom of the image which is what I imagine a giant berg would look like moving in the stream.


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Arctic sea ice / Re: The 2018/2019 freezing season
« on: November 28, 2018, 09:55:48 PM »
The permafrost in question is not soil, more ice/water than anything else. the specific heat of water is very high, it takes a lot of energy to raise it's temperature. It can accumulate energy almost to the degree the sea can and hardly warm up at all.

17
wonderfully clear view from sentinel [0.4/1.7] meanwhile despite the extensive calving including some very large icebergs the retreat in the fjord continues. polarveiw and the full moon tomorrow so more big tides in prospect.


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Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 21, 2018, 10:21:58 AM »
Perhaps we need an ice physics thread?

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Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 14, 2018, 12:29:24 PM »
In the ESS and north Laptev the water [beneath the ice] is cold enough to freeze
Using firefox I ctrl+ to 200% and set the speed at 200ms

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Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: October 10, 2018, 10:28:50 AM »
I think there's a threshold that needs forcing through, whilst there's enough ice around the pole to preserve an ice desert the ice will always regenerate and expand. The ice around the pole has to be accelerated to force it south, 0kph at the pole @175kph at the northernmost tip of Greenland, any wind powerful enough to do that also serves to enhance the ice deserts regenerative ability. The warm currents entering the Arctic either fall into the deeps or have too much inertia to move towards the pole, mostly both. We may have to wait until the temperature  of the ocean itself has the energy to cause bottom melt in the CAB.
 Looking at the various animations this year [thanks everyone] it seems pretty clear that the ice is expanding from the center out towards either the exits or to be destroyed by wave action, with the possible exception of ESS where there was thick ice left over from last season in sufficient quantity to almost serve as it's own ice desert. At the moment I can't see how a seperate area of thick ice could be established, so we may see the CAB under siege on all fronts. 

21
The collapse at the outer cill has been followed by a slow but continuous clearout, so far no sign of any concentration/blockage on the inner cills. It'll be interesting to see how close the retreat gets to the calving fronts.

29th 3rd

22
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 02, 2018, 11:20:25 AM »
Can someone explain me how so much heat can intrude towards the N.Pole from the Pacific? How can that happen? Any specific mechanisms?
I'll take a punt, Amundsen is not huge lets say 300 by 100 km and the tides are not huge .2-.6m but it's the only game in town. The tidal forcing twice a day drives a current across the Canadian/Alaskan mainland that detatches the incoming Pacific water from the coast at times and consistently provides resistance to it's ingress. The Pacific water backs up and flows instead into the deep west of Chuckchi Plateau here it meets and mixes with the increasing flow of Atl. water coming past the Lomonosov ridge. Some fraction gets caught up in turbulence caused by the tail end of the Amundsen driven current. Just as Amundsen drives water out twice a day so it draws it in, from the general direction of NSI but likely from just north of Chuckchi plateau. The easiest fraction of water to move is the surface so the Pacific waters are also drawn into the area where the Amundsen bound surface current begins.
   It's well worth looking through the various parameters at the link, i do full tilt/full screen, there's nothing that looks too different to other models.
The link done.

23
There's always a long wait for action on a glacier, except for the pressure of the ice sheet forcing glacial movement and compressing the sea ice, it seems we have to continue waiting till next season. Does this mean that more cold fresh water has been passing through Fram? or perhaps that tides/currents have carried warm Atlantic water, that previously would be forced south, through to ?Laptev?ESS? Whatever    despite this corner of Greenland seemingly melting almost as fast as anywhere south it appears there's been a sea change. I guess we'll have to see what happens when the ice cover expands enough to suppress tidal effects in the Arctic. It looks like the sea is close to freezing over

polarview

24
 It looked like the cill at Disko was stopping flow, but even after the tides peaked it's broken free and looks to have set everything in motion again.


from polarview

25
There are a couple of zoomables on polarveiw just now that show the area, the tidal 'lake'  of 79N has melted, and there's an area south of Zach. isolated but clearly affected by tides + melt that may signal the start of the melt season hereabouts.

26
Through the clouds,

yesterday there was an image where it looked possible that a dam was forming no sign in that powerful flow.

27
Calving continues,


sentinel 22nd gain.4 gamma1.5

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Interesting feature ene of the calving front, with a large meltpond just a little further out.

sentinel
Looks like 79N is primed for action too.

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Arctic sea ice / Re: The 2018 melting season
« on: August 06, 2018, 11:06:46 AM »
"Hot spots" both are the result of deep warm water being forced upwards the one to the south-west at the end of a long trough , the other at the end of the bear island trough, i have no opinion about how hot they are, but their actual temp. as published varies seasonally.
 
Looks to me that this season [and next] may be defined by how much fresh Beaufort water is lost through CAA/NWP

30
28-29 ooops more like 19-29, [cloud settings]

 

sentinel

31
 
 

from  24:06/06:07/21:07 24th already primed and moving then a massive outburst from the north sweeps away the previous bergs from the south, then in turn all the rest is pushed out by all fronts retreating 

32
Arctic sea ice / Re: SMOS
« on: July 22, 2018, 01:06:37 AM »
OT but 'Atlas' carried the sky on his shoulders, actually inside his head he was a navigator in the days before maps and atlas's curiously. Without complete star knowledge sailors got lost.

33
Some serious action under the new moon tides, from Sentinel


gain 0.4 gamma 1.7

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Antarctica / Re: Rift in Larsen C
« on: July 19, 2018, 11:19:58 PM »
It's actually rotated somewhat this month and is now more broadside on to the tides, i guess once the ice clears it could be moved north more rapidly.  In one of the recent shots from polarview it was hard against the shelf.


polarview

35
From sentinel meltponds on the two ice streams. 12th

 


36
How come?
 I'm guessing but the big bergs come from the deeper cuts in the fjord, their release indicates bottom melt/seawater penetration. It may be the case that they can only move towards the calving front down the deepest channel, and that they are forced to the south of that channel by the two ice streams falling into the northern side of the southern branch. Those two ice streams are indicated by the overturning features on that flank. Just as they get stranded on the cills down the fjord they are held up until they can pass over the threshold of the deep channel.

This is a detail from the 3rd showing the bulge on the front where the big bergs hold things up [?], and the two overturning ice streams falling into the fjord, the second being +/- an order of magnitude smaller.

from sentinel.

38
The southern face continues to calve and to discharge water, judging by the movement. I doubt the northern front has slowed, nevertheless it's ice-stream has been squeezed.
 
 from sentinel

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Arctic sea ice / Re: How soon could we go ice free?
« on: June 16, 2018, 02:36:28 AM »
I'm looking at ice dynamics, there are 3 main factors afaics, the main one being the expansion/dispersion of ice with every weather change. That is that as the ice moves creating gaps these are rapidly filled with new ice, the cumulative effect is to push the ice south away from the centre of the ice mass, generally south. As the ice moves south to maintain station it has to accelerate by about 24kph per deg, it doesn't, hence it appears to rotate c/w,  there are pinch points and the ice builds up against the coast, where?   well as far south as Prince Patrick island on the american side, and after the freedom of Beaufort from the NSI through NZ-FJ to Svalbard on the Russian side.
The next factor is the entry of Atlantic water, previously the ice in Barents suppressed the tides, I think ocean currents are residuals of tidal movements, the tides are no longer suppressed and new currents are forming, these currents help to keep Barents free of ice, being free of ice gives the wind free reign, so over the continental shelf the waves thrash the ice, it melts and no longer rotates to accumulate on the american side.     
The third factor is an ice free Amundsen gulf, every tide there can shift a significant fraction of 20,0002km of seawater/ice westward across southern Beaufort, and conversely suck in a similar amount from further north in Beaufort.
Nothing to do with ice but one has to bear in mind that Atlantic/Pacific waters entering the arctic tend to rotate ccw.
If the growing currents coming in from the Atlantic can weaken the ice over the ESAS in concert with weather systems bringing heat from the south, and persistent winds from E/W then the Siberian shelf will also become a killing field for ice. Which gives the possibility of no ice to rotate into the islands, no ice to rotate back towards Amundsen, whats next?
 Well given that systems tend to hold on beyond any reasonable expectation and then suddenly collapse, it's remotely possible that it happens this year, but I don't think we've passed beyond reasonable expectation yet we're close.

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Arctic sea ice / Re: Arctic Image of the Day
« on: June 14, 2018, 05:46:42 PM »

Interesting rope-like image [of overturning current?] south east of Svalbard 10th

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Clearer image today, some potential of a jam at the cill but 6 days til' new moon maybe 8 to peak tides before we'll know. Detail

from http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201806/S1A_IW_GRDH_1SDH_20180607T095201_499D_N_1.8bit.jp2

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Antarctica / Re: Rift in Larsen C
« on: May 26, 2018, 10:37:47 AM »
Nice shot of the continued break-up

from polarview

43
Just checked to see if the fjord has jammed up, it looks free to flow, so we should see some action during the next full moon tidal cycle.


top image from polarview

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Antarctica / Re: Rift in Larsen C
« on: May 18, 2018, 12:43:51 PM »
The point of contact has broken.

from polarview

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Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: May 16, 2018, 01:13:21 AM »
I'm thinking some deep Atlantic water was drawn through, quite how I don't know, energetically it should move ccwise. However if it is drawn through north of Greenland it would be full of rotational forces and would affect the ice from below, close to the coast but more pronounced along the edge of the shelf. It started around the 7th and seems to be building up again. I don't recall seeing anything like this before, so it may be something new or perhaps just more apparent due to thinning ice, either way since the tides are peaking we should see some action over near 120e 82n if what I'm thinking is valid.














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Antarctica / Re: Rift in Larsen C
« on: May 14, 2018, 10:42:59 PM »
"I'm curious why/how"
 It's worth considering the tides rotating clockwise through Weddel, being inhibited by the island, and forcing the island north. The islands cliffs are what 200ft high?, the warmer waters passing through are going to find the shallowest way through at the north end of the island, eventually cutting a deep gouge on the underside, maybe? It does look like some of the ice directly north of the island is new which may indicate deeper warm waters surfacing and briefly clearing the ice.

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-snip- The distinction between socialism and capitalism is not as powerful as the ideologues would have us believe. They are both growth systems with the predominant difference being how the pie is divided. snip
The real distinction is that in capitalism man ruthlessly exploits man, in socialism it's the other way round.

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