Please support this Forum and Neven's Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - nukefix

Pages: [1] 2 3 ... 9
1
Hint: Now that winter is coming start using S-1 SAR, it's great for glacier monitoring... ;)

2
Arctic sea ice / Re: The 2017 melting season
« on: September 18, 2017, 12:47:55 PM »

3
Arctic Background / Re: Whose data is wrong?
« on: September 13, 2017, 10:46:10 AM »
I am really puzzled by the assertion in the cited article that the collapse of the western ice shelf in Antarctica would raise sea levels by 6 meters. I understand that nuance is not the forte of the media, but what the article should have said is that if the ice shelf were to collapse, the conditions required for this to happen would be accompanied by rapid flow of glaciers into the ocean, which would be the actual cause of sea level rise. Ice shelves melting per se cannot raise sea level since they are floating and, according to Archimedes principle, already displace a volume of water equal to their mass.
You've misunderstood. The part of the West Antarctic Ice Sheet (WAIS) that is unstable and likely to raise sea-levels is the ice-sheet itself, not the floating ice shelves. WAIS is up to 2000m thick and laying on bedrock way below current sea-level, which makes it inherently unstable. It has collapsed before in warmer climates and is likely to do that again if warming continues.



4
I think there has been meltwater exiting Zach that has been melting sea-ice close to the calving front. The feature 1st appears on the 26.8. S-2 image:

http://apps.sentinel-hub.com/sentinel-playground/?lat=78.98372644988251&lng=-20.759353637695312&zoom=11&preset=1_NATURAL_COL0R&layers=B04,B03,B02&maxcc=100&gain=0.3&gamma=1.0&time=2015-01-01|2017-08-26&cloudCorrection=none&atmFilter=ATMCOR&showDates=true&evalscript=

5
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: August 31, 2017, 02:27:48 PM »
DMI say net mass loss p.a. is circa 200 gt due to peripheral melting and glacial loss.
That's in a normal year I reckon.
QUESTIONS:-
- What will the net mass loss be in 2017? Depends on snowfall now to December ? (see next question) Will have to wait for NASA's GRACE system to tell us next year?
I wonder if zero net mass-loss or even net gain is possible this year. BTW GRACE is about to die and the data is getting more and more patchy. We must hope that the GRACE Follow-On launches and works without a glitch (godspeed!).

6
Arctic Background / Re: Whose data is wrong?
« on: August 30, 2017, 09:52:21 AM »
...
You have not provided any references asserting that the Greenland ice sheet can produce Heindrich-style events during this interglacial. You also made unsubstantiated claims about catastrophic subsidence that can soon take place in the Melville-bay sector. Sorry to say but this smells like FAKE THREATS that are without basis.  :o >:( :(

7
Arctic Background / Re: Whose data is wrong?
« on: August 29, 2017, 05:26:01 PM »
Nevertheless his work, with all it's faults, shows the consistency of the ancients stories and warnings about when the earth stopped spinning, some experiencing prolonged day others night.
Nice fairy-tale. Or where do you reckon the angular momentum and the associated ginormous amount of energy went, and how did it return?

8
Arctic Background / Re: Whose data is wrong?
« on: August 29, 2017, 09:48:37 AM »
As per the isostatic rebound across the Melville Bay front, note the image of 2010 anomaly how sensitive that isostatic rise is to weather events like snow or rain accumulation v. off-loading by melt.
Yes, this is normal. On top of the "slow" ground uplift happening due to removal of huge ice masses at the end of the last ice age, there's also a "fast" component of uplift that happens very rapidly (~immediately) when ice-mass is removed. Therefore the "anomaly"-plot shows the anomaly against average "slow" and "fast" uplift. As indicated in the figure I posted, the Melville-bay area is rebounding very rapidly at about 1-2cm per year (average "slow" + average "fast" over the GPS time-series).

There will be a tipping point where this reverses as slushy, water-infested ice begins to pack against the Melville Bay.
That does not appear to be possible.

9
Arctic Background / Re: Whose data is wrong?
« on: August 28, 2017, 04:52:09 PM »
I hope I'm not off topic here, but there is a possibility, a strong possibility in my mind, that an asteroid strike on the Laurentide ice sheet brought on the Younger Dryas, shattered the ice sheet, and ended the Rancholabrean mammals reign in North America. A boundary layer referred to as the "Black Mat" that is rife with nano diamonds, iridium, and fused carbon is evidence of the event.
If this did occur it makes the ending of the last ice age a unique event, and comparisons of it to modern warming inconsequential.
Terry
This hypothesis does not seem to be very popular today:

https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis

10
Arctic Background / Re: Whose data is wrong?
« on: August 28, 2017, 04:16:47 PM »
Please post the references/citations here please, of course only published research will do. No need to have secret papers on shady hard disks :P

There was a lot more ice around at the end of the last ice age than now, including now extinct ice sheets. Therefore it's not surprising to me that bigger icebergs were being created. If you think there's a threat please show the references...


11
Arctic Background / Re: Whose data is wrong?
« on: August 28, 2017, 09:33:42 AM »
The ice dome not only causes perimeter's vertical uplift to form an elevated shield around the ice dome's edges, but also a spatial tightening of the continental edges when the ice pushes the interior down the edges get squashed tighter. Similarly, the Weischelian Ice Sheet's outlet that crossed across the middle of Sweden has almost completely disappeared by now. (This palaeo-strait let ice out from the Baltic Sea Ice Dome which sat at the centre of the Weischelian Ice Sheet). Even as recently as in the Middle Ages, the Viking's Capital, Birka, was at the seaside in the middle of Central Sweden. Today it is far inland and only the deepest part of that palaeo ice stream carved strait remains water-covered as a freshwater lake.

The above process will cause Melville Bay initially to subside catastrophically by water infested slushy ice (post-sea summer ice era), in the process causing turbidic rockfalls and pulling flat shoreline into a tight neck (like currently in Ilulissat).

Subside catastrophically? What are you talking about? Reality-check: Melville-bay is rebounding fast (see Fig. 2) and this is only going to increase if and when the ice-sheet thins out:

http://www.pnas.org/content/109/30/11944.full.pdf

Once the ice is off-loaded, the wet solidus damage and the nucleation of gases in asthenosphere fluids drives isostatic uplift. This produces either a tight Ilulissat-type narrow passage surrounded by mountains on both sides. Or, if the discharge of rock is large enough to produce a sufficient 4th rapid erosion force (planing), enough abrasion can occur to remove rocks to get the Hudson Strait type wide opening to form there.

You have not posted any references that point this being a glaciological concern in the near future of GIS.

12
Arctic Background / Re: Whose data is wrong?
« on: August 26, 2017, 12:16:02 PM »
Note that I have not said what Nukefix must have mis-read. We fear the failure occurs in future after the Arctic Ocean is summer-time ice free from midseason and it requires EXHAUSTIVE surface melting. I never said such situation is there already, nor anyone worried nuclear reactors say so.
I don't think that is glaciologically possible, according to present understanding the Greenland ice-sheet just isn't unstable the way WAIS is. Or can you find recent research articles arguing so?

BTW this is why I called the claim "alarmism" - scientists could not invent threats and present them to the parlament/media as their reputation would be seriously damaged.

13
Arctic Background / Re: Whose data is wrong?
« on: August 25, 2017, 11:34:14 AM »
The situation now is very much different with that at the end of the last ice age with regards to land ice and glacial lake configuration. WAIS-collapse is discussed a lot in scientific literature, but I haven't seen glaciologists arguing that anything similar could happen in Greenland, even in theory. There is no underwater-channel into the interior of the Greenland ice-sheet, except a very narrow one at Jakobshaven. In particular NEGIS is being blocked by an inland-ridge several hundred meters above sea-level (see bedmap2), and that is before any rebound that takes place when the overlaying ice-sheet thins due to warming.

14
Arctic Background / Re: Whose data is wrong?
« on: August 24, 2017, 10:28:21 AM »
(3) Heindric Ice Berg Armada (= Ice Debris Flows + Slip-Slide Ice Discharges + Hydrofracturing of North Greenland Ice Sheet on land + Rapid Erosion Forces + Perimeter and Continental Slope Failures), producing the job finished:
This is 100% a glaciological prediction - can you find peer reviewed publications by glaciologists predicting this mode of ice-sheet failure in Greenland? I've spent quite a bit of time talking about the Greenland ice sheet with professional glaciologists and I don't recall it ever been mentioned. References please.
Hey VAK care to comment on the above? Have you invented a new failure-mode for the Greenland ice sheet or is this already known in the glaciological community?
These are the only pieces I could find on Heidrich events in the future of Greenland, not very convincing and lacking proper references:

https://robertscribbler.com/2013/08/08/climate-monsters-we-want-to-keep-in-the-closet-heinrich-events-superstorms-and-warming-the-deep-ocean/

https://robertscribbler.com/2014/03/17/nature-human-warming-now-pushing-entire-greenland-ice-sheet-into-the-ocean/

Are there any credible papers that claim parts of Greenland are unstable so that they can trigger "catastrophic" events? Let's see them.

15
Arctic sea ice / Re: Latest PIOMAS update (August mid monthly update)
« on: August 23, 2017, 11:10:24 AM »
I do not believe there is any major sea ice rebound until there is next Heindrich Ice Berg Calving event from Greenland that pumps large amounts of meltwater and slushy ice into the ocean.

Hey VAK, I have to ask you again, what is this?? If I'm not mistaken you've written about it into report for UK parlament(!). I hope this is not something you've just made up, but is actually a concern in the glaciological community.

I know this is off-topic, I propose the discussion should be moved here where I've already raised this question a couple of times:

http://forum.arctic-sea-ice.net/index.php/topic,635.msg125647.html#msg125647

17
Arctic Background / Re: Whose data is wrong?
« on: August 17, 2017, 05:15:27 PM »
(3) Heindric Ice Berg Armada (= Ice Debris Flows + Slip-Slide Ice Discharges + Hydrofracturing of North Greenland Ice Sheet on land + Rapid Erosion Forces + Perimeter and Continental Slope Failures), producing the job finished:
This is 100% a glaciological prediction - can you find peer reviewed publications by glaciologists predicting this mode of ice-sheet failure in Greenland? I've spent quite a bit of time talking about the Greenland ice sheet with professional glaciologists and I don't recall it ever been mentioned. References please.
Hey VAK care to comment on the above? Have you invented a new failure-mode for the Greenland ice sheet or is this already known in the glaciological community?

18
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 16, 2017, 11:23:50 AM »
Amazing blue iceberg spotted in Jakobshaven icefjord:

http://apps.sentinel-hub.com/sentinel-playground/?lat=69.16542768047643&lng=-49.78935241699219&zoom=12&preset=1_NATURAL_COL0R&layers=B02,B08,B12&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-08-10&cloudCorrection=none&atmFilter=ATMCOR&showDates=true&evalscript=

19
Arctic Background / Re: Whose data is wrong?
« on: August 13, 2017, 11:10:14 AM »
(3) Heindric Ice Berg Armada (= Ice Debris Flows + Slip-Slide Ice Discharges + Hydrofracturing of North Greenland Ice Sheet on land + Rapid Erosion Forces + Perimeter and Continental Slope Failures), producing the job finished:
This is 100% a glaciological prediction - can you find peer reviewed publications by glaciologists predicting this mode of ice-sheet failure in Greenland? I've spent quite a bit of time talking about the Greenland ice sheet with professional glaciologists and I don't recall it ever been mentioned. References please.

20
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 11, 2017, 11:41:04 AM »
A beautiful Sentinel-1 track crossed Greenland yesterday...while sightseeing I managed to spot both the Greenland summit site and the NEGIS coring site on the imagery. Images downloaded from PolarView.

21
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: August 11, 2017, 10:10:04 AM »
It's devastating for the local wildlife. Tundra grows very slowly.
I would think it's a normal part of nature there.

22
Arctic sea ice / Re: The 2017 melting season
« on: August 10, 2017, 10:54:47 AM »
Here's the cloud coverage situation on Friday at 1200UTC.

That's one I don't think I've seen before. Gotta link?
That's from ECMWF directly so it's not freely available...(a pity).

23
Arctic sea ice / Re: The 2017 melting season
« on: August 10, 2017, 10:11:55 AM »
"...to finish the job?"
Misconception. I disagree! The job isn't "finished" at that point, but only at its very beginning! The ocean melting advances and its re-freeze delays further. This exposes the ocean to sunlight much closer to the solstice and then staying exposed to that sunlight for longer.
But it looks like none of the sunlight is hitting the surface directly due to extensive coverage of low clouds this summer. This could be a feedback resulting from more open water that is preserving the ice.

edit: here's the cloud coverage situation on Friday at 1200UTC. Sun can only hit the surface full on in white areas & the colours depict low/medium/high cloudiness situation.

24
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 09, 2017, 10:32:06 AM »
It's not cloud. The ridge can be seen in the ice on this Aug 4th image from WorldView. Could it be bands of thicker ice formed originally by ridging that are now moving? Similar patterns also appear in the areas that are melting out inside the ice perimeter.
My guess is it's a shadow of a contrail. I saw one crossing southern Greenland from an airplane and it really looked odd before I understood what it was..

25
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 07, 2017, 07:19:00 AM »
"When will AGW accelerate the loss ?"
When the meltwater of the interior gets access to the ocean?
Indeed. Or when Zachariae Isstrom decides to let all hell break loose.
According to Bedmap2 there's only limited scope for retreat at NEGIS.

26
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: August 04, 2017, 04:52:57 PM »
The fire looks great in S-2 SWIR-combination:

http://apps.sentinel-hub.com/sentinel-playground/?lat=67.84888987414084&lng=-51.514892578125&zoom=12&preset=91_SWIR&layers=B8A,B03,B02&maxcc=100&gain=1.0&gamma=1.0&time=2015-01-01|2017-08-03&cloudCorrection=none&atmFilter=&showDates=false&evalscript=

It could burn until the next rain I guess..

27
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 04, 2017, 03:46:16 PM »
NASA GRACE analysis from 2002 shows almost linear Greenland Ice Sheet mass loss trend. When will AGW accelerate the loss ?
Arguably this already happened in the 1990's...but yes melting can potentially increase by a lot and we could have more summers with 2012-like extreme melt...

28
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 04, 2017, 11:56:42 AM »
Ice sheets that are grounded on an inward-sloping submarine bed are fundamentally unstable, for example WAIS. In Greenland this is not expected to happen as the topography of the bedrock is much more benign:

https://www.the-cryosphere.net/7/499/2013/tc-7-499-2013.pdf

Jakobshaven goes deep inland under present day sea level but it's narrow. Mean-image of S-1 over 2017 brings the movement out nicely..

ps. I'm not familiar with the acronym GDF?


29
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 03, 2017, 04:14:27 PM »
Here's the mean backscatter of a large stack of Sentinel-1 HH SAR images taken this year. There's are several ice-streams in the picture but no rifts..

30
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 03, 2017, 11:48:01 AM »
I re-enclose the rift image a year ago 24.07.2016. If you had read my paper with care, you should have seen this link to the original NASA image (ref: endnote No. 40).
I don't see a "rift", only some topography-related differences in brightness. They could be related to bedrock-topography but I don't see anything out of the ordinary. I'm also checking a stack of Sentinel-1 radar images via Google Earth Engine and everything looks fully normal.

31
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: August 02, 2017, 04:56:33 PM »

As I commented elsewhere the slope of Greenland margin is small and not conducive to rapid runaway collapse than can happen on much steeper mountain glaciers.

ps. can you share the location of the NEGIS-crevasse you mention, it would be interesting to track it with Sentinel-1?

32
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 02, 2017, 03:07:09 PM »
By mid-September much of ice could be so thin and disperced that satelites won't notice it

SAR will still see it, unless it's possibly some kind of slush, but I don't think that is a stable configuration for the ice (?).

http://www.polarview.aq/arctic

33
Arctic sea ice / Re: The 2017 melting season
« on: August 02, 2017, 03:02:31 PM »
The low-lying north Greenland ice sheet builds water within its ice and beneath it most rapidly until the whole flat-lying ice sheet collapses due to (the newly discovered) process "Glacier Debris Flow" (GDF):  Meyer, Robinson: "When Glaciers Transform Into Deadly 150-mph Avalanches - After happening only once in the 100-year record, catastrophic glacial collapse occurred twice in Tibet this summer", The Atlantic | Science, 18 October 2016.
That is needless "alarmism". The slope of the Greenland ice sheet is just a few degrees close to the coast (+it's a lot flatter everywhere else) - this very effectively prevents it from turning into a 150-mph avalanche!

34
Interesting that it all moves in concert, suggests to me that it's driven by escaping melt water, not that tide action can altogether be ruled out.
I think that's rather standard with a calving, it looks like the new calved iceberg pushes everything away and ice-melange & sea-ice transfer that impulse quite far.

35
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: July 25, 2017, 05:22:23 PM »
Also the contrast of 2017 with 2012 is spectacular. It has always added to my conviction that 2017 was not going to see a massive sea ice melt.
My thinking is that there's a limited amount of extra heat around - if Greenland is super-warm some other area is therefore cooler and sometimes this can conserve sea-ice. So let's see...

36
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: July 22, 2017, 12:04:58 PM »
The Greenland surface melt products are sensitive to the presence of small amounts of liquid water (wet snow) on the surface. The SMB can still be positive when surface melt (=wet snow) is detected on the ice sheet.

37
Arctic sea ice / Re: The 2017 melting season
« on: July 21, 2017, 12:23:14 PM »
Whats been driving me quite bananas over the last few week is how rare it seems to be to get anything but a few tiny gaps in the clouds to see what the ice really looks like.

Luckily we'll always have radar ;)

http://www.polarview.aq/arctic



38
Arctic sea ice / Re: The 2017 melting season
« on: June 29, 2017, 10:28:15 AM »
I found this sea-ice portal by the Alfred Wegener Institute and University of Bremen...should be added to the resources I think:

http://www.meereisportal.de/en/

39
Wonderful clear skies on the 26th Jakobshavn retreats on all fronts if you have the time take a look round.
Wonderful image...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...

40
There's no way a 4.0 earthquake can start a tsunami. It might trigger a landslide or huge calving though. I'd look through satellite imagery including Sentinel-1 and try to identify what has changed.

41
Petermann "wakes up" in July, at least in the past two years. Image source: Enveo Cryoportal

42
Arctic sea ice / Re: The 2017 melting season
« on: May 29, 2017, 04:25:45 PM »
The probabilistic extent 50 days from now is in freefall..:

http://cires1.colorado.edu/~aslater/SEAICE/

43
Antarctica / Re: PIG has calved
« on: May 07, 2017, 05:02:28 PM »
The pixel noise in these Sentinel radar images make it hard to be sure. But it looks as some more opening/deepening at the ends of the crack.
Yes, if there's coherence InSAR would be the way to see the progress for sure.

44
Policy and solutions / Re: Becoming Vegan.
« on: May 04, 2017, 12:45:35 AM »
Most people most of the time through most of history (at least since the Agricultural Revolution) have been mostly vegan.
AFAIK that is total bullshit. There are no vegan indigenous people, not even a single culture.

45
The rest / Re: Real Stupid Blog-Posts
« on: April 29, 2017, 05:17:54 PM »
It just funny that someone attacks the argument "The arctic could be virtually ice free in a couple of summers" on the basis that it hasn't happened yet. The argument is true and there are high odds for yet another record low this summer...

46
The fjord is always pretty full of icebergs and they also flush out.

47
Arctic sea ice / Re: The 2017 melting season
« on: April 29, 2017, 12:28:41 PM »
The ice around Newfoundland is almost certainly the result of collapsing glaciers not sea ice. Its one area where an increase in 'sea ice' can be expected as glacier collapse in Greenland becomes more prevalent.
Why would glacier mass-loss cause that? Something to do with the extra meltwater?

48
The rest / Real Stupid Blog-Posts
« on: April 27, 2017, 02:43:03 PM »
This is a very, very dumb video from the denialist-fringe:

https://realclimatescience.com/2017/04/new-video-can-we-trust-climate-scientists/

Let's see what he says after the next record low.. :o

49
Interesting, does the AMO-reconstruction show the abrupt end of the LIA, or something else?

50
Arctic sea ice / Re: The 2017 melting season
« on: April 19, 2017, 08:32:28 PM »
Neven,

Yes, therefor i use the finnish service for Snowmass, because they cutting out mountain sides: http://www.globsnow.info/swe/GCW/


AFAIK the Globsnow algorithm is the best-in-business currently.

Pages: [1] 2 3 ... 9