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Messages - bairgon

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1
Antarctica / Re: Antarctic Icebergs
« on: April 29, 2020, 08:21:50 AM »
Interesting that the recent calving made so much progress but the main body did not.

Might imply that the main body is grounding; but I would expect the calving to be as deep as the main body. Bathymetry implies that any ridge for grounding is to the north, unless the calving has slipped through a gap.

The calving, being smaller, may be more influenced by wind and current and therefore moved more.

2
Antarctica / Re: PIG has calved
« on: February 11, 2020, 01:37:18 PM »
Cork zoom.

Observations:
 - some large bits of the SW tributary have broken off as well, letting the cork float free.
 - the "melange" hasn't moved. Is it stuck in place via sea ice?

3
Antarctica / Re: PIG has calved
« on: February 08, 2020, 12:07:27 PM »
Looks to me as if R3 has widened. This is the 4th vs. the 6th.

What's very evident in this gif is the difference in movement between the front of the proto iceberg vs the crack to the main glacier. It is swinging out quite a lot.

4
Indeed, thanks.

Unfortunately I can't get Sentinel images as I'm getting a JSON error message saying "RATE_LIMIT_EXCEEDED".

5
An irrelevant calving happened at Spaltgletscher AKA Big Foot between Aug 1 and Aug 2 2019:

On the same day Gammel Hellerup (I think), just to the south, moved fairly significantly:

6
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 10:47:30 PM »
It's blowing from the Atlantic through Baffin and the CAA. It's going against the current through Nares and exiting into the Lincoln Sea at 20 knots +, bringing some warm air with it.

Certainly is. The Parry Channel has started to break up, but was torched today:

7
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 11, 2019, 11:23:17 PM »
Further to the Kane Basin fast ice disintegrating, there are several grounded icebergs

Thanks for the reminder, Tor - had almost forgotten about that bit of research I did! Have been following this thread with interest this year.

8
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: April 27, 2019, 09:18:38 PM »
Looks like a big floe has blocked the channel. I wonder how long this will last.

Click to animate.

9
Antarctica / Re: PIG has calved
« on: February 16, 2019, 02:45:55 PM »
The blue marked iceberg is grounded and is located at the same place for quite a while now.

That is now on its way. See below.

10
Antarctica / Re: PIG has calved
« on: February 07, 2019, 09:17:12 AM »
   .   .   and another spray of ice from the SE corner of the glacier front on 2019-02-06   .   . (top left of image)

That appears to be a new calving with some bergs, but a lot of brash ice. See https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=-74.93585300426079&lng=-100.777587890625&zoom=10&preset=CUSTOM&layers=B01,B02,B03&maxcc=76&gain=1.0&gamma=1.0&time=2018-08-01%7C2019-02-06&atmFilter=&showDates=false&evalscript=cmV0dXJuIFtCOEEqMSxCMDMqMSxCMDIqMV0%3D

Edit: Checking that URL shows an image for 6th Feb and I can't seem to get to 7th of Feb now. But I definitely saw it earlier today - as per the screen shot below.

11
Antarctica / Re: PIG has calved
« on: February 04, 2019, 08:56:57 PM »
CPOM does an automated version of what you are doing with Sentinel 1 images 6 days apart:

Ah, that's a great resource. And indeed the flow rate from the first analysis is lower than the average, and the rate from the latest analysis is greater than the average. The change is only about 9% - 11 m/day to 12 m/day - but that is in just over 3 years.

12
Antarctica / Re: PIG has calved
« on: February 04, 2019, 01:26:09 PM »
Pine Island Glacier: 18 months of flow and calving
https://adrianluckman.wordpress.com/2019/01/25/


My best estimate of flow rate from this video, picking a feature and seeing how far it moved on my screen vs the scale is that flow is 4.5 km per year, which exceeds recently reported flow rates of "up to 4000m per year" e.g. http://www.antarcticglaciers.org/glaciers-and-climate/shrinking-ice-shelves/pine-island-glacier/

Since the recent calving there is visible movement on Worldview in a month. Using Sentinel, comparing the images from 28/12/2018 and 31/01/2019 it appears the rate is around 4.6 km per year (430m in 34 days). So it is maintaining the faster rate.

Resolution on Worldview is too low to be accurate.

13
Arctic sea ice / Re: The 2018 melting season
« on: August 15, 2018, 12:12:40 PM »
I've tried a different exercise with the Lincoln sea ice.

I chose a floe visible in a Sentinel image, and followed it backwards (and forwards - this took a little time to prepare) in time. The animation below shows images rotated and matched.

The floe is currently about 20km north of the fast ice breaking out of the bay to the south of the Lincoln Sea.

The images were captured at the 300m scale and the floe is about 2km x 2km.

It seems that it suffered a lot of fracturing early on, but more recently has held its shape very consistently.

14
Arctic sea ice / Re: Arctic Image of the Day
« on: August 01, 2018, 11:33:20 PM »
Quite a lot of fog in Barrow Strait today. It finishes at Griffith Island (alt 130m), near Resolute - see below.

See Worldview. Worth following back down the Strait for more wonderful effects.

15
Arctic sea ice / Re: The 2018 melting season
« on: July 27, 2018, 07:25:42 PM »
Reviewing the ice on the Pacific side over the last week or so, it seemed to have suffered significant damage in the images from the 19th and 22nd of July. Checking back in Nullschool shows that a lot of heat was being brought through from the Pacific on those days.

Looking ahead shows some more coming through on the 29th/30th, but also predictions for a lot of heat on the Atlantic side. The image below is for August 1st, 13:00 UTC.

Given the state of the ice in the Lincoln sea (as posted up-thread) this could have a similar effect.

16
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 11, 2018, 08:56:42 AM »
The Lincoln polynya is opening up, but not through the normal mechanism of a bridge holding back flow down Nares. Over the last few days there has been a prevailing SW wind up Nares Strait, which is pushing back the ice in the Lincoln Sea. The polynya has reached around 2500 km^2 (50km x 50km).

This implies to me that the ice in the Lincoln Sea is very fractured. In past years I've seen it easily hold a bridge. This year, when flow was down the Strait after the bridge broke, fracture lines were evident far out into the Lincoln Sea. Now, that fractured ice is not holding. It's possible to see signs of melting in the polynya - at NASA Worldview. There appear to be trailing melt from the floes and the edge of the ice is very smooth implying wave action is melting this. On the 9th the wind was 44 km/h at 3 degrees C.

The forecast for the next 5 days on Nullschool is continuing winds from this direction and temperatures above freezing, so this should continue to grow.

17
Arctic sea ice / Re: The 2018 melting season
« on: July 01, 2018, 10:10:44 AM »
As pointed out earlier in this thread, Nares is starting to show export from Lincoln again. See more in the Nares Strait thread:

The beginning of the end of the Kane Basin bridge.  DMI's Sentinel-1 today

Parry channel is also opening up. Yesterday's Worldview image shows a large crack near Resolute.

18
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: June 29, 2018, 11:55:21 PM »
The Lincoln sea ice is already funnelling into the gap left further up the channel. With the collapse of the arch this should continue.

Click to animate.

19
Signs of breakup further up the Strait.

20
Yes, I've been watching it slowly being eaten away, with a lot of melt on ice further down the channel.

Looking at the other end shows massive breaks like the picture below from yesterday (the cracks have closed up a bit today). This shows that the normal bridge of thicker ice that normally forms from the top of Greenland is non-existent this year.

21
Arctic sea ice / Re: The 2017/2018 freezing season
« on: February 02, 2018, 12:16:24 PM »
Lincoln Sea Nares. More fast ice letting go?

Actually, as can be seen in the gif in the message below, all the ice there was fairly mobile recently. Appears to have stopped on 30th Jan, and started forming an outer "bridge" between Ellesmere and Greenland. However, as you point out this is decaying rapidly.

Lincoln Sea Nares Export from 2017-12-24 to 2018-1-24. One tracked section of ice traveled approximately 115 miles (185km) in 31 days.  Furthest travel in one day was approximately 12 miles (19.3km).

22
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

Quote
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.

23
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:



24
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.

25
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.

26
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?

27
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.


28
Could you post a link to the glacier on the Sentinel playground please?

Edit: Found it here

29
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.


30
Arctic sea ice / Re: Arctic Image of the Day
« on: July 01, 2017, 07:27:05 PM »
Duck or dragon? Hopen island today

31
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.

32
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.

33
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.

34
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.


35
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.

36
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?

37
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.

38
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

Quote
Melting and cracking – is Antarctica falling apart?

Quote
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.

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

39
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.

40
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.

41
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.

42
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.

43
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.

44
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.

45
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.

46
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

47
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 :-)

48
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.

49
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?

50
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.

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