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Messages - bairgon

Pages: [1] 2 3
1
Antarctica / Re: What's new in Antarctica ?
« on: August 13, 2017, 07:43:46 AM »
Guardian article: "Scientists discover 91 volcanoes below Antarctic ice sheet"

https://www.theguardian.com/world/2017/aug/12/scientists-discover-91-volcanos-antarctica

Scientists have uncovered the largest volcanic region on Earth – two kilometres below the surface of the vast ice sheet that covers west Antarctica.

The project, by Edinburgh University researchers, has revealed almost 100 volcanoes – with the highest as tall as the Eiger, which stands at almost 4,000 metres in Switzerland.

2
Arctic sea ice / Re: What the Buoys are telling
« on: July 27, 2017, 08:41:01 PM »
That is starting to look quite like this pic from the Nordica:

From David "Duke" Snider, ice pilot aboard Nordica:

Plus thick FYI in Peel Sound:



3
Arctic sea ice / Re: The 2017 melting season
« on: July 24, 2017, 11:21:52 PM »
Its not blue /grey from meltponds, its so thin you can see the sea thru it and is melting right out before it makes it 100km down Nares strait.

Its a slurry of salt ice slush and floating snow with a few old remnants embedded in it.
And its starting to flush through all the CAA channels.


First image: Sentinel from 4 days ago. Looks like melt ponds to me.

Second: Worldview from 24th July 2016. The state of the ice looks very similar to 2017.

I do agree that this doesn't look like strong 3-4m ice, and it isn't making it down Nares.

4
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 24, 2017, 06:07:55 PM »
Interesting to compare that to September last year - see Worldview 10th Sept 2016.

It's clear that the fast sea ice breaking up in 2017 is only FYI. Also visible is the ice shelf, which is also "fast" but clearly is much older.

5
Arctic sea ice / Re: The 2017 melting season
« on: July 19, 2017, 08:48:22 AM »
McClure Strait and Parry Channel.

This shows that the ice has collapsed almost overnight, fracturing at both the western and eastern end of this channel.

As this is my first year watching a melt season via satellite, I have no experience of whether this is normal or not.

What mechanism could account for this? Is it bottom melt which has thinned the ice to a critical point?

6
Arctic sea ice / Re: What the Buoys are telling
« on: July 18, 2017, 09:47:16 PM »
PolarView image doesn't show the big crack anymore (Where'd it go?).

Ah - perhaps the explanation is that the ice in the channel all collapsed. Rather impressive polynyas on the north side visible on Worldview now.


7
Could you post a link to the glacier on the Sentinel playground please?

Edit: Found it here

8
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 01, 2017, 11:05:01 PM »
the shadow of the main branch looks like it will allow the estimation of the calving front height via using incidence angle & sun elevation angle at the time of imaging...


Looking at the calving front of Humboldt Glacier, shadows can be seen in the lee of the icebergs.

Using the scale and a mm rule my best guess is that the shadows are around 40m. Using the excellent suncalc website for that date and changing the time to match the shadows shows that the height of the iceberg is around 25m.

Assuming that the iceberg has a linear profile (i.e. it doesn't get fat underwater) then the draft of the iceberg would be around 175m.

The bathymetry map attached shows a ridge about 100m deep running parallel to Humboldt, explaining why these icebergs get stuck.


9
Arctic sea ice / Re: Arctic Image of the Day
« on: July 01, 2017, 07:27:05 PM »
Duck or dragon? Hopen island today

10
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 01, 2017, 08:21:37 AM »
Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here.


I found a sequence near the bell floe on Sentinel - at this link - that shows this very clearly.

The GIF below starts at 16th June and skips cloudy days. The last image is the last available, from 29th June.

Points to note: watch the triangular-shaped iceberg at top right. It moves a little, seems to get stuck, and then gets knocked out of position by some sea ice and appears at bottom left. You can also see another square-ish iceberg which moves out of the original line but ends up stuck despite the sea ice coming through.

Also note the difference in the colouring. The sea ice is clearly covered in melt ponds, but the icebergs stay gray presumably because they are not flat. I've put in a nice shot at full resolution illustrating this from 27th June.

Edit: corrected left/right; and note that the triangular iceberg is around 300m long.

11
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 01, 2017, 01:04:19 AM »
(There are a few quite small floes (bergs?) near the lower right corner of this animation that don't move, including a "" shaped one.) [Bell Floe is about 15 km wide.]


Those look to be either land masses or glitches on the image because they don't move one iota despite all the movement around them.  I have tried to enlarge the image but all I get is large pixels, without definition enough to discern their true nature.  They are very small.  I wonder if there is someone with more detailed knowledge of the waters in that area, or maybe access to images with better resolution.

Update:  if you go to 24th September 2015 you will see something in the exact same spot that doesn't move in the days either side.  There is more ice but the same spot is there.


As I stated a little while ago, with a link to Sentinel which shows much better resolution:

Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here.


I found a reference to the Humboldt Glacier calving front being up to 50m high. That would give a considerable depth below water. As the icebergs are in lines I expect there are some old sills at that end of Kane basin.

12
Arctic sea ice / Re: The 2017 melting season
« on: June 30, 2017, 07:20:04 AM »
Big Fat wad of warm moist air penetrating deep through the CAB towards CAA and Greenland from Bering Strait region over next day.

That is already having an effect. GIF below is west of Mackenzie Bay, northern Canada. I was struck by how quickly the floes are melting with the warm air coming through. According to Nullschool it will be continuing for a few days in this area.

13
Arctic sea ice / Re: The 2017 melting season
« on: June 29, 2017, 07:11:22 PM »
The ice packed above Severny island looks to be in sunshine too.

Definitely getting warm up there. This is the fate of some fast ice on the mainland (opposite the ice packed on the island). It has separated and just about melted in 6 days.


14
Arctic sea ice / Re: The 2017 melting season
« on: June 25, 2017, 03:47:23 PM »
Another area showing the effect of the winds is the Lincoln sea. The wind is going to be from the west or south west over the next few days. Will the fractured ice be swept together?

Yesterdays's view showed a polynya forming. Worth watching over the next few days.

15
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 24, 2017, 03:09:40 PM »
Kane Basin is deep; there are no grounded icebergs in its middle.

The bathymetry that you referenced only covers the south-western end of the basin.

Do you have another explanation for the static elements in this gif below?

16
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 24, 2017, 07:46:14 AM »
Some time back I asked this question:

I was also struck but what appear to be a line of fixed items across (Kane) basin. Are there small islands here?


Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here.

17
Antarctica / Re: What's new in Antarctica ?
« on: June 23, 2017, 02:09:12 PM »
Article on the UK Guardian newspaper website today about the changes in Antarctica and whether they are due to climate change. https://www.theguardian.com/science/2017/jun/23/melting-and-cracking-is-antarctica-falling-apart-climate-change

Melting and cracking – is Antarctica falling apart?

The answer to these questions is no. Glaciologists are not alarmed about most of these processes; they are examples of Antarctica simply doing what we know Antarctica has done for thousands of years. But because there is a potential link between the ice sheet and climate change, glaciologists are suddenly faced with a situation where the spotlight is on our science on a seemingly daily basis, and every time a crack grows, or a meltstream forms, it becomes news. The situation is a conundrum: we want people to be aware of Antarctica and concerned about what might happen there in the near future as climate changes. But hyping research results to sound like climate change, when they are just improved understanding of natural behaviour, is misleading.

Helen Amanda Fricker is a professor at the Scripps Institution of Oceanography

18
Arctic sea ice / Re: Stupid Questions :o
« on: June 21, 2017, 08:50:36 AM »
Is this mud?  Is it from a stream or melting permafrost or what?
Second image zoomed out for reference

Looks like silty river flow to me - and appears to be the Amguema. See https://en.wikipedia.org/wiki/Amguema_River. Very similar to the Mackenzie delta, though on a smaller scale. See the gif below.

The Mackenzie delta melt has been impressive since then. See animation from 1st June below.

19
Yep, that does look like a crack on the left?

Yes, looks like it has been developing over the last few days. Animation from 16th June below - it was cloudy before then.

20
Arctic sea ice / Re: The 2017 melting season
« on: June 19, 2017, 07:47:31 AM »
I guess, based on HYCOM ice thckness animation, that the MacKenzie delta has given way for a large melt pulse. As the ice is disappearing fast phase in the MacKenzie Bay and around it in the Beaufort.
You better look at the worldview images https://go.nasa.gov/2ri0zKP
There is ice movement away from the coast, surface melt on landfast ice, an ice free McKenzie river and some recently formed ice melting away in the Beaufort. Not all opening water equates to ongoing melt. Open water absorbs sunlight and will melt ice because it is warming up now, but that takes a while to come together.

The Mackenzie delta melt has been impressive since then. See animation from 1st June below.

21
Arctic sea ice / Re: The 2017 melting season
« on: June 10, 2017, 07:21:11 PM »
foehn wind north of Greenland is producing 8 to 9 degree temperature is the from just above ground level to 1.5 km up.

That has created some melt ponds today in the fjords on that coast (the darker blobs are cloud shadows). Note the loss in land snow cover over the last 5 days. The loose ice is being pushed away from the coast with the wind but doesn't show particular signs of melting.

22
Arctic sea ice / Re: The 2017 melting season
« on: June 06, 2017, 07:29:17 AM »
In the meantime I'm really wondering how long it can be so warm on the shores of Hudson Bay (80F/27C forecast tomorrow for Port Nelson.. with rain!) without the ice just off the shore melting or showing any negative impacts. I can't imagine much worse weather for ice...

If the below is anything to go by, it won't be long. This is 11 days from 26th May.

23
Arctic sea ice / Re: The 2017 melting season
« on: June 05, 2017, 10:55:20 PM »
The last one is of an area of Parry Channel which appears to be melting out rather than breaking up (though other areas further down have broken up).

That has now triggered a spectacular breakup in the Parry Channel.

24
Arctic sea ice / Re: Latest PIOMAS update (June)
« on: June 03, 2017, 09:56:37 AM »
The gridded thickness animation of May 2017. The situation in the Fram is crazy.

And note the 4m stretch to the north of Greenland. Near the end of the animation you can see it start to disappear as it prepares to be flushed down Nares.

25
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 01, 2017, 11:33:55 PM »
Cross post - NASA commentary on the Nares Arch:


Is there any history of this area being open... ever(in the satellite era, anyway)? Along the Greenland North coast, I mean.

I'm not really sure what the implications of it is, so I'm curious if there's anything comparable that's happened.

You can read more about the event here: https://earthobservatory.nasa.gov/IOTD/view.php?id=90245

26
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 01, 2017, 11:24:45 PM »
NP. It's the way science works - independent confirmation of results. I respect this forum for its scientific and facts-based approach.

There may be the odd radical theory :-)

27
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 01, 2017, 08:30:08 PM »
That's good to have independent confirmation of my earlier guess:

Assuming that we have an additional 2 month's flow through Nares compared to previous years, that is an additional 60 km^3 lost which is, very roughly, about 2-3% of the total ice volume in September.

28
Antarctica / Re: Rift in Larsen C
« on: June 01, 2017, 07:03:28 AM »
See earlier in the thread for a discussion about that:

Apologies if this has been asked before....but is the Larsen C INCLUDED in the "sea ice" numbers....or are the ice shelve's NOT included in the sea ice numbers?

29
Arctic sea ice / Re: What the Buoys are telling
« on: May 31, 2017, 11:41:55 PM »
There is a stretch of sea ice along the coast which is actually melting

I posted about that over in the melting thread:

The last one is of an area of Parry Channel which appears to be melting out rather than breaking up (though other areas further down have broken up).

It's certainly been interesting since then; though it looks like the ice will soon collapse as a large area has cracked.

30
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 31, 2017, 08:12:36 PM »
Does the current also explain the way the ice is separating from the north of Greenland for a considerable distance? There seems to be a movement away from Fram and towards Nares, even across the far side of the northern headland on Greenland.

There was a mention recently of a current becoming established in Nares, and then being self-sustaining. If that is the case then perhaps we will see a continuous clearing of the top of Greenland throughout the summer.

Would dearly like to know what Andreas is thinking about this ATM.

Edit: Perhaps explained by the drift today: see

The ACNFS drift forecast.

31
I had noticed that the brown colour in the valley to the west of the glacier had increased recently. Perhaps the winds are coming from the Strait and blowing south on that valley as well as the glacier, and melting the snow/ice.

32
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 29, 2017, 10:05:22 AM »
I've been watching this ice separating in the Kane basin recently.

That was big chunk which is no more.

Now the remains of the ice are being hammered. See Worldview.


33
Arctic sea ice / Re: The 2017 melting season
« on: May 28, 2017, 01:59:51 PM »
Cross post from Nares Strait thread; relevant for overall melting progress.

To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.

At a very rough guesstimate of area, that is a triangle with sides of 140km. That works out to around 8500km^2. The last image in the sequence is 27th May, so that is 15 days of export.

Therefore export rate is around 550 km^2 per day. That matches well with my original estimate of 500km^2:

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day

34
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 28, 2017, 01:57:01 PM »
To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.

At a very rough guesstimate of area, that is a triangle with sides of 140km. That works out to around 8500km^2. The last image in the sequence is 27th May, so that is 15 days of export.

Therefore export rate is around 550 km^2 per day. That matches well with my original estimate of 500km^2:

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day

35
Arctic sea ice / Re: The 2017 melting season
« on: May 28, 2017, 10:11:26 AM »
@bairgon
Here's another little area that's opening up. These will soon add up.
First image is for point of reference.


What has struck me about that image is that the top of Baffin Bay is clear. Big chunk collapsed, and the export from the Lincoln Sea has reached that area, but there is little sign of the ice filling up the top of Baffin Bay. It's all melting. The ice that is in Baffin Bay is now making its way south, and will melt out, but nothing is replacing it.

Animation below shows this.

36
Arctic sea ice / Re: The 2017 melting season
« on: May 28, 2017, 12:51:07 AM »
Two meter waves in Nares and Kane Basin right now with 50km/hr winds.
Bigger waves predicted in the same area for two days starting tomorrow. Will be curious to see the effects, as if the situation could get worse. At the very least some of the nearby passage ice may get busted up.

Extra clear image of Nares and Kane today, with many areas affected. It looks like a blowtorch has hit.

I've chosen a few areas for the animations below. The last one is of an area of Parry Channel which appears to be melting out rather than breaking up (though other areas further down have broken up).

See Worldview

37
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 21, 2017, 09:49:03 AM »
I found this in https://icyseas.org/2015/07/13/oceanography-of-nares-strait-ice-flushing/:

"Now there is more to the “hill” story that is modified near the surface by the earth’s rotation in a fluid that has different densities at different depths. In a nutshell, the surface flow is 2-3 times as strong as the depth averaged flow. Furthermore, the surface flow on the Canadian side of Nares Strait is often twice as strong as that closer to Greenland, but all these spatial variations in flow actually help to smash large pieces of ice by moving and rotating them different sides of the same large piece of ice differently."

38
Arctic sea ice / Re: The 2017 melting season
« on: May 18, 2017, 10:58:32 AM »
Possibly pertinent to this, and relevant also for the discussions regarding the potential cold anomaly due to export of ice out of the Lincoln sea due to collapse of the arch: I noticed this area of ice on Kane basin being eroded. It almost seems to be melting rather than fragmenting. Does this imply that insolation is already having an effect?

I was also struck but what appear to be a line of fixed items across the basin. Are there small islands here?

Worlview link: 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=2017-05-17&z=3&v=-537239.8684391112,-1080127.498859606,-332439.86843911116,-981183.498859606&ab=off&as=2017-05-11&ae=2017-05-17&av=1&al=false

39
Arctic sea ice / Re: The 2017 melting season
« on: May 16, 2017, 04:12:52 PM »
Any idea how Nares compares with Fram on volume basis?
Looks like Nares export (on any measure) will be unusually large this year, owing to lack of arch formation.

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day (each of the big rectangular blocks are around 20k x 10k). If the ice is 2m thick that is about 1 km^3 per day.

Assuming that we have an additional 2 month's flow through Nares compared to previous years, that is an additional 60 km^3 lost which is, very roughly, about 2-3% of the total ice volume in September.

So it's not very significant; but could make an impact in the thickest area.

40
Arctic sea ice / Re: The 2017 melting season
« on: May 15, 2017, 10:26:46 PM »
It's also evident from the latest Lincoln pictures - see http://ocean.dmi.dk/arctic/lincoln.uk.php - that there is a slumping of a lot of ice to the north of Ellesmere Is., towards Nares. That doesn't show up in the Worldview shots.

Compare http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20170514s01b.ASAR.jpg and http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20170515s01b.ASAR.jpg between browser tabs.

The flow down Nares appears to be strong with no sign of the chunks of ice forming another arch.

There is a triangle of stationary ice at the top of Greenland, and the flow of ice towards Fram appears to have stopped (the line across the top of the picture).

41
Arctic Background / Re: Barneo 2017
« on: May 10, 2017, 07:36:32 AM »
Darwin father-son duo navigate shifting ice, avoid polar bears during North Pole Marathon

"Unlike any other marathon around the world, the North Pole Marathon takes place on drifting ice.

While running the distance, competitors also drift more than one kilometre across the ocean."

http://www.abc.net.au/news/2017-05-10/darwin-father-son-duo-complete-north-pole-marathon/8510768

42
Arctic sea ice / Re: Arctic Image of the Day
« on: May 08, 2017, 01:55:16 PM »
Big block 2017 is no more - though it is a little difficult to tell through the clouds.


43
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 03, 2017, 09:32:03 PM »
I've been watching this ice separating in the Kane basin recently. For the latest picture see 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=2017-05-03&z=3&v=-749189.3189376687,-1208306.8597371846,-257669.3189376687,-956146.8597371846&ab=on&as=2017-04-18&ae=2017-05-03&av=2&al=true

I think it's about 30km by 80km, which is 2400 km^2. Rather a lot really!

Winds are forecast to be from the southwest so it may travel up the strait a bit before being flushed out.

45
Arctic sea ice / Re: The 2017 melting season
« on: April 19, 2017, 06:51:43 PM »
Some major cracks north of Ellesmere Island and Nares Strait have appeared overnight.

There are also smaller cracks above the Nares arch - see 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=2017-04-18&z=3&v=-335502.5695521517,-818827.6264782081,-89742.56955215175,-692747.6264782081 and gif below.

This also shows that the month-old ice in the polynya has given way.

There is also a crack on the coast of Greenland (explore on Worldview using link above).

46
Arctic sea ice / Re: Arctic Image of the Day
« on: April 19, 2017, 07:18:14 AM »
Grounded iceberg near Ferryland, Newfoundland - see http://www.bbc.co.uk/news/world-us-canada-39632047


48
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: April 13, 2017, 12:44:10 PM »
I think that's out of the new ice in the "polynya" which is breaking up. If you look carefully you can see the outline of the original boot arch which is bigger.

49
Arctic Background / Re: Barneo 2017
« on: April 04, 2017, 12:01:31 PM »
Using http://www.movable-type.co.uk/scripts/latlong.html they have moved 66.8 km in 9 days, or around 7.5 km per day. Those skiers better get there quickly or they won't be able to get to the pole!

50
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: March 18, 2017, 06:24:18 PM »
Looks like it's given way:


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