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numerobis

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Re: Arctic Image of the Day
« Reply #1050 on: November 16, 2017, 03:08:52 PM »
Without a zoom lens I can't capture the beauty of the morning.

The bay is steaming. It's still open water, but the air is -20 C. The islands in the inlet look like they're floating. Then add the sunset on that.

Jim Hunt

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Re: Arctic Image of the Day
« Reply #1051 on: November 18, 2017, 12:11:03 AM »
The Arctic moving image of the day:



Via SpaceWeather:

Quote
On the evening of Nov. 16th, aurora tour guide Tony Bateman of northern Finland was indoors, warming up between auroras, when his surroundings began to vibrate. "There was a huge bang and the cottage shook violently," he reports. "At first I thought it was an earthquake. Or maybe a tree fell on the cottage roof! I walked outside and inspected the trees. Everything looked okay." A quick replay of his aurora webcam solved the mystery. "It was an incredible meteor," he says.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

litesong

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Re: Arctic Image of the Day
« Reply #1052 on: November 30, 2017, 03:37:17 AM »
The Arctic moving image of the day:

Via SpaceWeather:
"It was an incredible meteor," he says.
[/quote]
Don't have pix, but 3 stories about meteors here:
One of my astronomy students had really gotten interested in astronomy during my classroom studies & our nighttime mountain top telescope observations, over looking a valley. One night he took his wife out to the mountain top & he pointed out the constellations & a few celestial objects they could see through binoculars. Then she saw a bright light out of the corner of her eye. It was a meteor, but not one 20 to 50 miles away. The meteor came towards them at an angle, burning past them at only 1 or 2 miles distance, descending down the valley. Behind the valley were distant mountains, & the meteor was BELOW the horizon. After passing them, at roughly 3 to 5 miles distance, the meteor blew up & flashed out of sight.
//////
We were observing at a star party, among high mountains. In the darkness, I was talking with 3 people, who I only saw as dim shadows. Suddenly, a brightness lit up behind me, which I thought was headlights turned on. Then, the incoming meteor, hit the lower atmosphere, & like a huge camera flash, the meteor brightly lit up the mountains for 20 miles around. I turned around to see the meteor dying out. But as I turned, the after-image of the 3 people in the darkness, followed my sight picture on my retinas.
//////   
 Was observing a meteor shower at a star party & I had my tripod mounted 20x80 binoculars. One very bright meteor streaked across the sky, & I was barely able to binocular see the tail-end of the meteor streak as it died out. Lots of ohs & ahs for that meteor could be heard in the night, but quickly people looked other places, waiting for more meteors. However, I continued to observe the sky where the meteor died out & shouted out that I could still see the meteor contrail in the sky. People said no way. But those who came over & looked through my binoculars also saw the contrail. Finally, people left. I was trained to observe very low surface brightness galaxies & with those techniques, I continued to observe the contrail. After 15 minutes, I could still see the contrail. Two other people looked through the binoculars, confirming my report. After 20 minutes, I could still see the contrail, but.... no one came to look. They were busy seeing bright meteors, not long gone ultra-dim meteor smoke. ha ha ha
   

sesyf

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Re: Arctic Image of the Day
« Reply #1053 on: December 01, 2017, 06:25:42 PM »
The finnish astornomical society, Ursa, ( https://www.ursa.fi/english.html ) has calculated where the meteor landed from received reports. Probably now the remnants are covered in snow, so there will be an attempt to find some of them in the spring.

Pavel

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Re: Arctic Image of the Day
« Reply #1054 on: December 10, 2017, 09:06:01 PM »

philiponfire

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Re: Arctic Image of the Day
« Reply #1055 on: December 17, 2017, 08:22:39 AM »
To assert that the death of this polar bear is anything to do with climate change is totally spurious unless there is evidence that this was a young healthy bear in the first place. looks to me like an old bear dying naturally.

jdallen

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Re: Arctic Image of the Day
« Reply #1056 on: December 17, 2017, 09:07:14 AM »
...looks to me like an old bear dying naturally.
You base you conclusion on what evidence?
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Pmt111500

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Re: Arctic Image of the Day
« Reply #1057 on: December 17, 2017, 10:08:50 AM »
The finnish astornomical society, Ursa, ( https://www.ursa.fi/english.html ) has calculated where the meteor landed from received reports. Probably now the remnants are covered in snow, so there will be an attempt to find some of them in the spring.

So it happens the thing fell on about the remotest area possible to reach by anyone in Finland. Area's close to Russian border so using snowmobile or ATV requires permits and you'd need to have border patrol with you. You can walk or ski on the area freely and possibly meet one of the three persons living in the area. Think central Alaska 30 miles from nearest settlement of 10 people.
« Last Edit: December 17, 2017, 10:22:41 AM by Pmt111500 »
Cooling the outside by heat pump.

echoughton

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Re: Arctic Image of the Day
« Reply #1058 on: December 17, 2017, 11:12:54 AM »
Well Mr. Allen, can you support any claim that man burning FF had a part in the demise of this or any other polar bear?

Espen

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Re: Arctic Image of the Day
« Reply #1059 on: December 17, 2017, 11:42:31 AM »
To me this bear looks far more hungering than the bear discussed?
Have a ice day!

magnamentis

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Re: Arctic Image of the Day
« Reply #1060 on: December 17, 2017, 08:03:53 PM »
A video of a starving polar bear in the Baffin Island
http://video.nationalgeographic.com/video/news/171207-polar-bear-starving-iceless-land-vin-spd

is there any evidence that this bear is not dying according to his age or starving because of injuries or illness. i hope it's clear that i'm totally convinced of man made climate change happening and that there are consequences for fauna and flora but in another article it was claimed that this bear is dying naturally, not climate related and while i can't tell the facts, the question alone implies that such images should only be posted with claiming a climate change relation if there is either evidence and/or founded reason to believe that at least in parts it's related.

i know that whenver i posted such "warnings" in the past they were not helpful so whoever doesn't like this post can save his breath. i strongly believe that half-true or untrue or not proven information will be exploited by the contrarians and not help our cause but damage it.

please remember that the post starts and is a question, followed by the reason to ask, not a statement, hence if anyone knows where is evidence that this image is not out of context but indeed shows a bear, starving BECAUSE of climate change, be so kind and link me there because the purpose of all is to gather knowledge based on facts or reason.

Dharma Rupa

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Re: Arctic Image of the Day
« Reply #1061 on: December 18, 2017, 02:46:33 AM »
...i strongly believe that half-true or untrue or not proven information will be exploited by the contrarians and not help our cause but damage it.
I don't care what the contrarians think/do, and I don't think we have a "cause" other than to be fair witness.

Kate

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Re: Arctic Image of the Day
« Reply #1062 on: December 22, 2017, 12:03:55 PM »

echoughton

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Re: Arctic Image of the Day
« Reply #1063 on: December 22, 2017, 12:52:51 PM »
It's not argument, Kate. It's discussion. When the motive is to pin this poor animal
s demise on AGW, I think it is lazy and not at all scientific. It is presented by some to alarm.
I read your accompanying articles and nothing was answered regarding climate change causing this bear to starve....although lack of ice there may be a direct result of AGW. This bear certainly could have cancer, or be very old...who knows?

Neven

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Re: Arctic Image of the Day
« Reply #1064 on: December 22, 2017, 10:24:23 PM »
It's not argument, Kate. It's discussion.

The same kind of discussion we had in the 60s and 70s wrt smoking.  ;)
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echoughton

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Re: Arctic Image of the Day
« Reply #1065 on: December 23, 2017, 01:17:42 AM »
The same kind of discussion we had in the 60s and 70s wrt smoking

How do you copy...like in the box with quotes? This copy and paste is not the same.

echoughton

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Re: Arctic Image of the Day
« Reply #1066 on: December 23, 2017, 01:20:12 AM »
The same kind of discussion we had in the 60s and 70s wrt smoking

The same kind of discussion we had in the 60s and 70s wrt smoking

How do you copy...like in the box with quotes? This copy and paste is not the same.

Martin Gisser

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Re: Arctic Image of the Day
« Reply #1067 on: December 23, 2017, 01:33:08 AM »
It is presented by some to alarm.

Since this is an images thread I herewith challenge you (reader) to present one interesting image of a nontrivial planetary biogeophysical phenomenon (preferably arctic) that can be argued to have no causal connection to the present carbon pulse. 8)

charles_oil

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Re: Arctic Image of the Day
« Reply #1068 on: December 25, 2017, 01:50:10 PM »
Keeping a careful lookout - no sign of A68 here.  Did see a couple of Christmas dolphins though.... 

Espen

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Re: Arctic Image of the Day
« Reply #1069 on: January 04, 2018, 09:50:48 PM »
I totally agree with Steve:
Have a ice day!

gregcharles

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Re: Arctic Image of the Day
« Reply #1070 on: January 05, 2018, 05:15:26 AM »
I totally agree with Steve:

Me too, but not on much else.

A-Team

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Re: Arctic Image of the Day
« Reply #1071 on: January 06, 2018, 08:23:09 PM »
Nice photo (click to view properly) below of walrus hauling out on some Arctic sea ice, where and when not provided.

Despite it all being in plain view, I am totally baffled (as usual) as to how it should be scored for area, extent, concentration, thickness and volume. For example, what is the freeboard on that slanted floe behind the walrus? How should that jumble of snow, ice and air be treated? What do the various satellites see looking down?

Life is so much easier when some algorithm with 25 km x 25 km does the scoring and gives us a single number for the whole Northern Hemisphere.

A-Team

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Re: Arctic Image of the Day
« Reply #1072 on: January 11, 2018, 03:26:50 PM »
Here is an odd bit of floe motion that occurred this fall during the big ice pack lurch to the west and CW rotation, Nov  27 - Dec  17 . The circled block of ice is pinned between the immovable islands of the CAA and the main westward moving ice pack. It responds by rotating in position.

We see this same effect happening to tributary ice streams over a 15 year time scale on the east side of Petermann glacier, see gif animations on that forum.

It is also very similar to what happened over 20 myr to the Transverse Range off Santa Barbara, Ca (the same area in the news because of the Thomas Fire and subsequent landslides). The plate tectonics there was animated years ago by Tanya Atwater of UCSB.

http://emvc.geol.ucsb.edu/2_infopgs/IP4WNACal/dSoCalifTect.html
« Last Edit: January 12, 2018, 10:38:24 AM by A-Team »

Jim Hunt

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Re: Arctic Image of the Day
« Reply #1073 on: January 12, 2018, 10:17:49 AM »
Via Twitter:



Quote
Flying over the Confederation Bridge, Prince Edward Island at 7500'
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Tor Bejnar

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Re: Arctic Image of the Day
« Reply #1074 on: January 12, 2018, 02:17:54 PM »
Curious:  I could download and watch A-Team's "SoCalif_Tectonics (T Atwater).mp4" but not his "transverse range block rotation in CAA.mp4".  (I could also download the GIF.)
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Sleepy

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Re: Arctic Image of the Day
« Reply #1075 on: January 12, 2018, 03:43:57 PM »
Missing codec? Here it is as gif, slighty reduced.
Omnia mirari, etiam tritissima.
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Tor Bejnar

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Re: Arctic Image of the Day
« Reply #1076 on: January 12, 2018, 06:34:28 PM »
Thanks, Sleepy!
Totally cool depiction of the rolling floe.
And A-Team's geological parallel is now in context.  (I just wish it would take as long for the Arctic ice to melt as it will take for San Francisco to enter Canada.)
Arctic ice is healthy for children and other living things.

magnamentis

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Re: Arctic Image of the Day
« Reply #1077 on: January 19, 2018, 07:14:10 PM »
Ilulissat, Greenland

simply beautiful

 8)

numerobis

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Re: Arctic Image of the Day
« Reply #1078 on: January 22, 2018, 12:09:08 AM »
I got a nice view of the floe edge on my flight in on Friday. It's not too far out of town.

(The Canadian Ice Service maps show this as 100% land fast ice.)

A-Team

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Re: Arctic Image of the Day
« Reply #1079 on: January 23, 2018, 05:23:03 PM »
Here far more accurate bathymetry (ARDEM 2.0) of the Bering, East Siberian, Chukchi and Beaufort seas is used to recreate Beringia at various sea level heights during the late Pleistocene and Holocene. (Various hill-shaded versions have appeared before on other forums.)

The Bering Strait itself has a 53m sill applicable the whole time as a lack of nearby ice sheets means no isostatic correction is necessary in this region (eg Wrangel Island was never glaciated and only became an island at -35m). The earliest inflows of Pacific waters to the Arctic Ocean have been dated accurately to 11,000 BP by sediment core layers; that is quite a good match to the ARDEM depiction at -53m.

There's also special interest in the inundation history of the ESAS in view of thawing currently submerged methane deposits in what was once land permafrost. The animation here shows continental shelf out to 200m depth although sea level was only -145m at the Last Glacial Maximum.

We might also wonder about how sea level affected circulation in a one-portal Arctic Ocean and what vast exposed continental shelves meant for ice pack persistence and mobility.

Meltwater pulse 1A (MWP1a) was a period of rapid post-glacial sea level rise amounting to some 20 m in 450 years. The rate of rise peaked about 13,800 years ago; eustatic sea level at the Bering Strait at that time looks to be ~about 70m (wiki).

Here the animation runs forward and back at 10m increments from current sea level to the 200m isobath, which takes 21 frames. It could also be made at 5m or even 1m increments which would involve 42 and 210 frames respectively. These would barely remain displayable here as gifs because of file size. Alternatively the animation could be stepped in smaller increments around special depths such as opening of the Strait.

These higher resolution videos aren't feasible to make manually but using Dryland's new automation tool in PanoplyCl, a simple tabulation of sea level vs year can draw the map frames while inserting the applicable numbers (not shown) in each. The scripting language is transparent and a snippet is shown below:

// java -jar PanoplyCL.jar 53.pcl
// Open a dataset.
var ncdata1 = panoply.openDataset ( "/ARDEMv2.0.nc" );
// Select a variable.
var ncvar1 = ncdata1.getVariable ( "z" );
// Create the plot.
var myplot = panoply.createPlot ( "lonlat", ncvar1 );
myplot.set ( "title-text", "Land exposed in Beringia" );
myplot.set ( "subtitle-text", "[yyyy] years BP at sea level [xxx] m" );
myplot.set ( "font-master", "SansSerif" );
myplot.set ( "interpolate", true );
myplot.set ( "scale-colorbar", "CB_RdYlGn.cpt" );
myplot.set ( "scale-width", 40 );
myplot.set ( "scale-min", [-53.0] );
myplot.set ( "scale-max", 0.0 );
myplot.set ( "proj-name", "Stereographic" );
myplot.set ( "proj-lon0", -176.0 );
myplot.set ( "proj-lat0", 68.0 );
myplot.set ( "proj-xparam-1", 17.5 );
// Save plot image to disk.
myplot.saveImage ( "PNG", "53.png" );
« Last Edit: January 23, 2018, 05:56:18 PM by A-Team »

gerontocrat

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Re: Arctic Image of the Day
« Reply #1080 on: January 23, 2018, 08:00:03 PM »
Beringia land exposure at various Holocene sea levels.gif

That is more than good, A-team. But as always, a grovelling complaint or begging-letter for advice.

Is there an app (free of course) that lets me open and run the file but also lets me tell the file to speed up or slow down or even pause to capture an image ?

Yours, in hope,

Gerontocrat.
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numerobis

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Re: Arctic Image of the Day
« Reply #1081 on: January 23, 2018, 09:07:19 PM »
I bet excavations on those isolated flooded islands would be fascinating, to see what life evolved up there.

(Of course, I guess it would have been ice so megafauna could just walk off the islands.)

A-Team

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Re: Arctic Image of the Day
« Reply #1082 on: January 23, 2018, 11:08:49 PM »
Quote
free app .. open and run the gif animation   speed up slow down pause t capture an image ?
Sure, ImageJ, Gimp, Preview are free and easy all platform apps but first you might try just double-clicking on the download to see if your computer has something on board already that will open gifs. Web browsers work but are just players.

Quote
excavations on those isolated flooded islands would be fascinating, to see what life evolved up there. it would have been ice so megafauna could just walk off the islands.)
Wooly mammoths get all the attention. Populations got stranded on both Wrangel and St Paul after rising sea level cut them off from the mainland. The ones on Wrangel persisted for several millennia but eventually crashed from genetic inbreeding. The ones on St Paul supposedly trashed their only waterhole and eventually lost their access to drinkable water. The pygmy mammoths on the Channel Islands off California apparently swam there at LGM low sea stand.

I was not involved professionally with these particular mammoths but rather in sequencing the first nuclear genome, from frozen hair shafts, of an earlier one from mainland Siberia dated right at the LGM. I can take a look tomorrow to see at the sea level ARDEM has these islands getting cut off and when. However sea level rise was fairly slow plus if they could swim or walk off on ice, the dates will not be that pinned down that well.

The real challenge in Beringia is finding camps, villages, tools, boats or dna of the earliest transiting humans. It would almost all be underwater by now and archaeology in Arctic waters is not a pleasant snorkel like off Crete.

It's a nuisance having to digitize these sea level graphs which is necessary for the flooding animation to rise at the correct historic rate, so if anyone has seen a tabulation or polynomial fit or more recent version of the top graphic below, please post. Otherwise the (sea level, year) pairs will have to come off a finely regridded graphic.

https://io9.gizmodo.com/5896262/the-last-mammoths-died-out-just-3600-years-agobut-they-should-have-survived
http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006601

https://www.sciencedaily.com/releases/2016/08/160801163855.htm
http://www.pnas.org/content/113/33/9310.full
https://www.nps.gov/chis/learn/historyculture/pygmymammoth.htm

A-Team

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Re: Arctic Image of the Day
« Reply #1083 on: January 24, 2018, 02:37:06 PM »
Below, the graph above of sea level rise versus calendar year is digitized and implemented as a drowning map of Beringia. By 8,500 years BP, it was practically gone because the Beaufort has very little continental shelf and the East Siberian and Bering are broad but almost flat. The animation thus shows the inundation of land permafrost with consequences for the generation and escape of methane. The land bridge between continents disappeared at 11,000 BP as the Pacific and Arctic Oceans connected.

The following slide show illustrates that Beringia would not have been much enlarged had sea level dropped much further during the last glaciation, from -126 m to exposing the -250 m isobath.

yearBP,-mslr);(20000,-126.0,);(19500,-124.7,);(19000,-123.3,);(18500,-122.0,);(18000,-120.7,);(17500,-118.9,);(17000,-117.2,);(16500,-115.5,);(16000,-113.7,);(15500,-111.9,);(15000,-110.0,);(14500,-98.0,);(14000,-86.0,);(13500,-81.9,);(13000,-77.7,);(12500,-70.6,);(12000,-63.5,);(11500,-62.1,);(11000,-60.8,);(10500,-52.6,);(10000,-44.4,);(9500,-35.7,);(9000,-26.9,);(8500,-20.9,);(8000,-14.8,);(7500,-9.6,);(7000,-4.3,);(6500,-3.7,);(6000,-3.1,);(5500,-2.7,);(5000,-2.3,);(4500,-2.0,);(4000,-1.6,);(3500,-1.4,);(3000,-1.3,);(2500,-1.1,);(2000,-0.9,);(1500,-0.7,);(1000,-0.5,);(500,-0.2,);(,0,-0.0)
« Last Edit: January 24, 2018, 04:19:25 PM by A-Team »

gerontocrat

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Re: Arctic Image of the Day
« Reply #1084 on: January 24, 2018, 03:47:33 PM »
Sorry A-Team,

I looked but could not find

Quote
It's a nuisance having to digitize these sea level graphs which is necessary for the flooding animation to rise at the correct historic rate, so if anyone has seen a tabulation or polynomial fit or more recent version of the top graphic below, please post. Otherwise the (sea level, year) pairs will have to come off a finely regridded graphic.

I have downloaded gimp - will have a super time learning it? There are two definitions of GIMP below - I wonder which one I will end up using.

gimp - proper definition

noun
1.
twisted silk, worsted, or cotton with cord or wire running through it, used chiefly as upholstery trimming.
2.
fishing line made of silk bound with wire.

Urban Dictionary (slang): gimp

(1) a derrogatory term for someone that is disabled or has a medicial problem that results in physical impairment. (2) An insult implying that someone is incompetent, stupid, etc. Can also be used to imply that the person is uncool or can't/won't do what everyone else is doing. (3) A sex slave or submissive, usually male, ...
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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A-Team

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Re: Arctic Image of the Day
« Reply #1085 on: January 24, 2018, 04:02:16 PM »
General Image Manipulation Program. Unfortunate acronym but still makes for a good search term in conjunction with a tutorial topic or mission-critical plugin. ImageJ is far easier to use if just looking for a gif frame or montage viewing tool.

Here is a more uptodate treatment of sea level rise from global (Arctic not tabulated) ice volumes as well. The 2014 article has been cited 364 times, the place to look for 2017-18 updates (see below).

Sea level and global ice volumes from the Last Glacial Maximum to the Holocene
K Lambecka et al
http://www.pnas.org/content/111/43/15296.full.pdf open source

The major cause of sea-level change during ice ages is the exchange of water between ice and ocean and the planet’s dynamic response to the changing surface load. Inversion of ∼1,000 observations for the past 35,000 yr from localities far from former ice margins has provided new constraints on the fluctuation of ice volume in this interval. Key results are:

(i) a rapid final fall in global sea level of ∼40 m in <2,000 y at the onset of the glacial maximum ∼30,000 y before present (30 ka BP)

(ii) a slow fall to −134 m from 29 to 21 ka BP with a maximum grounded ice volume of ∼52 × 106 km3 greater than today

(iii) after an initial short duration rapid rise and a short interval of near-constant sea level, the main phase of deglaciation occurred from ∼16.5 ka BP to ∼8.2 ka BP at an average rate of rise of 12 m·ka−1 punctuated by periods of greater, particularly at 14.5– 14.0 ka BP at ≥40 mm·y−1 (MWP-1A), and lesser, from 12.5 to 11.5 ka BP (Younger Dryas), rates

(iv) no evidence for a global MWP-1B event at ∼11.3 ka BP

(v) a progressive decrease in the rate of rise from 8.2 ka to ∼2.5 ka BP, after which ocean volumes
remained nearly constant until the renewed sea-level rise at 100–150 y ago, with no evidence of oscillations exceeding ∼15–20 cm in time intervals ≥200 y from 6 to 0.15 ka BP

Oceanographic and Climatic Change in the Bering Sea, Last Glacial Maximum to Holocene
BM Pelto, BE Caissie, ST Petsch
Paleoceanography 2018

Post-glacial sea level rise led to a direct connection between the Arctic and Pacific
Oceans via the Bering Strait. Consequently, the Bering Sea experienced changes in
connectivity, size and sediment sources that were among the most drastic of any ocean...

The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin
M O'Regan et al
Climate of the Past 2017

Ice sheets extending over parts of the East Siberian continental shelf have been
proposed for the last glacial period and during the larger Pleistocene glaciations. The
sparse data available over this sector of the Arctic Ocean have left the timing, extent and ...

Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins
TM Cronin et al
Climate of the Past 2017

Deglacial (12.8–10.7 ka) sea level history on the East Siberian continental shelf
and upper continental slope was reconstructed using new geophysical records and
sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition.

Younger-Dryas cooling and sea-ice feedbacks were prominent features of the Pleistocene-Holocene transition in Arctic Alaska
BV Gaglioti et al
Quaternary Science 2017

Declining sea-ice extent is currently amplifying climate warming in the Arctic.
Instrumental records at high latitudes are too short-term to provide sufficient historical
context for these trends, so paleoclimate archives are needed to better understand the...

Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records
M Jakobsson et al

The Bering Strait connects the Arctic and Pacific oceans and separates the North
American and Asian landmasses. The presently shallow (∼ 53 m) strait was exposed during
the sea level lowstand of the last glacial period, which permitted human migration across ...

Deglaciation of the Laurentide Ice Sheet from the Last Glacial Maximum.
CR Stokes 2017 - dro.dur.ac.uk

The last deglaciation of the Laurentide Ice Sheet (LIS) was associated with major
reorganisations in the ocean-climate system and its retreat also represents a valuable
analogue for understanding the rates and mechanisms of ice sheet collapse...

Caribbean Reef Drowning During Slow Mid-Holocene Sea-Level Rise
P Blanchon et al 2017 osf.io

Predicting if reefs can keep pace with future sea-level (SL) rise is problematic
because accretion occurs over geological timescales. For example, although meltwater
pulses drowned reefs during postglacial SL rise, drowning has also been reported during...
« Last Edit: January 24, 2018, 04:20:22 PM by A-Team »

A-Team

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Re: Arctic Image of the Day
« Reply #1086 on: January 24, 2018, 05:28:36 PM »
The article below takes a close look at when Beringia shrunk to the point of isolating St. Paul Island and its mammoths from the mainland.

I could not quite confirm their dates using the latest Ardem 2.0 bathymetry which shows St Paul still having a land bridge at 12,500. It's murky though as mammoths were strong swimmers, salt water marshes might have offered habitat, Panoply linearly interpolates, and the authors use 'years ago' rather than BP (1950) of the sea level rise graph. They might also have used nautical charts which surprisingly are less accurate that Ardem's all-encompassing sonor records. Wrangel Island will be similarly ambiguous on date of mammoth isolation.

http://www.pnas.org/content/113/33/9310.full

St. Paul Island is a remnant of the Bering Land Bridge that became isolated between 14,700 and 13,500 y ago due to sea level rise during the last deglaciation. The island rapidly shrank in area until 9,000 y ago, and then slowly shrank until 6,000 y ago.. Today, St. Paul is highly isolated (>450 km from Alaska and Aleutians) and is characterized by maximum elevation 203 m above current sea level, a few freshwater lakes, no springs or streams, no permafrost, and moderately productive moss-herbaceous tundra vegetation.. Apart from a small population of reindeer introduced to the island in 1911, the largest terrestrial mammal on St. Paul today is the Arctic fox.
« Last Edit: January 24, 2018, 05:39:53 PM by A-Team »

Archimid

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Re: Arctic Image of the Day
« Reply #1087 on: January 24, 2018, 06:26:22 PM »
Quote
(v) a progressive decrease in the rate of rise from 8.2 ka to ∼2.5 ka BP, after which ocean volumes
remained nearly constant until the renewed sea-level rise at 100–150 y ago, with no evidence of oscillations exceeding ∼15–20 cm in time intervals ≥200 y from 6 to 0.15 ka BP

That’s a nice and favorable environment for civilization to grow. Stable temperatures and stable sea levels at a point in time when most of the surface is ice free for most of the year and the warm places are not too warm. 6 thousand years of paradise for H. Sapiens.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Sebastian Jones

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Re: Arctic Image of the Day
« Reply #1088 on: January 25, 2018, 12:30:28 AM »
Thank you A-Team for this wonderful set of animations.
The work you generally do is mostly concerned with current events, and is fascinating and informative in its own right, however this work fills me with wild surmises- how amazing it must have been to have witnessed the submerging of Beringia (well, part of it- I'm quite dry on this bit).

Pmt111500

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Re: Arctic Image of the Day
« Reply #1089 on: January 25, 2018, 10:24:43 AM »
We got some water rain here overnight. For water, it takes a while to penetrate the ice of the lake. Granted, it's not arctic here, rather the northernmost hemiboreal, but we get to see some normal wintery phenomena regularly still. Photo is about a week too late to include some visiting Steller's Eiders, which occasionally migrate through Finland.
« Last Edit: January 25, 2018, 11:34:00 AM by Pmt111500 »
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A-Team

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Re: Arctic Image of the Day
« Reply #1090 on: January 25, 2018, 08:41:47 PM »
Quote
how amazing it must have been to have witnessed the submerging of Beringia
It must have been quite the sight, people, bison, horses, lions, wooly rhinos, mammoths lining up to the land bridge at 11,001 BP but still hoping to wade across the sill at low tide. Same for the closing of the Isthmus of Panama at 3,500,000.

Quote
How the Isthmus of Panama Put Ice in the Arctic : Oceanus Magazine by GH Haug  Mar 22, 2004
www.whoi.edu/oceanus/feature/how-the-isthmus-of-panama-put-ice-in-the-arctic
https://phys.org/news/2015-04-evidence-isthmus-panama-earlier-thought.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988774/
http://www.pnas.org/content/112/19/6110
http://advances.sciencemag.org/content/3/6/e1602321.full

A growing body of evidence suggests that the formation of the Isthmus of Panama partitioned the Atlantic and Pacific Oceans and fundamentally changed global ocean circulation. The closing of the Central American Seaway initially may have warmed Earth's climate, but then set the stage for glaciation...  Closure is implicated in four major events in the history of Earth: the onset of the Thermohaline Circulation, the onset of Northern Hemisphere glaciation, the birth of the Caribbean Sea, and the Great American Biotic Interchange...

Here are some shaded relief bathymetry images, produced in-house by the Ardem group -- of areas near the Bering Strait that we re especially interested in. The first uses a logarithmic color palette and hill-shading, which is effective in highlighting bottom structures (such as fault lines that might provide vents for subsurface methane).

The animation shows the dramatic improvements the Arden project made vis-a-vis the older  IBCAO. It requires a click to show at the full resolution the authors intended. The upper portion shows most of the ESAS area where Shakhova and Semiletova do their submerged permafrost and methane release studies.

They entered some 600,000 triples (lat,lon, depth) off 315 historic Russian nautical charts from the Laptev, East Siberian, Chukchi, Bering, and Sea of Okhotsk. Those, plus sonar surveys and previous IBCAO bathymetry make up the content of the open source netCDF file used to make the imagery above. Even better, ARDEM data is offered as a geolocated Geo2D file (unlike IBCAO) which is critical to Panoply map-making.

Technical note: We could do the log scale readily in Panoply from the netCDF file and the latter by exporting both a grayscale with darkness proportional to log(depth) and a color version using our preferred Panoply palette. Then ImageJ could draw depths using the interactive '3D Surface Plot' and the color version used as drape. There's even a way now for web browsers to allow users to interact with files like this.  Panoply can also put out co-registered maps of bathymetry and Arctic ice displays such as UH sea ice concentration or Ascat scattering.

Quote
We have created the Alaska Region Digital Elevation Model (ARDEM), a bathymetric grid with nominal 1-km grid spacing over the domain 45ºN-80ºN and 130ºE-120ºW. The DEM is based nearly exclusively on ship sounding datapoints, including Electronic Navigation Chart point soundings, research vessel underway soundings, multibeam swath mapping datasets and digitized point soundings from paper nautical charts.

Depths from the International Bathymetric Chart of the Arctic Ocean (IBCAO) grid are used in the northern Chukchi Sea, the Beaufort Sea, and the northern East Siberian Sea.

In order to assist users that have interest in employing a combined bathymetric-topographic DEM, we have spliced the ocean DEM grid with land elevations from the Global Land One-kilometer Base Elevation (GLOBE) 1-km open source DEM....

The ARDEM grid is based in part on our previous digitization of 139 Russian nautical charts and chart inserts. In this project, we digitized 153 additional charts and inserts in order to increase data density in coastal arctic regions having sparse data coverage.

https://www.uaf.edu/cfos/research/projects/alaska-region-digital-ele/
http://s3.nprb.org/projects/40093f37-6464-439e-a836-c84a2998ecec/FinalReport1225.pdf
https://eos.org/project-updates/sounding-northern-seas 
« Last Edit: January 26, 2018, 12:32:41 AM by A-Team »

A-Team

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Re: Arctic Image of the Day
« Reply #1091 on: February 01, 2018, 02:01:41 PM »
Here is a kaleidoscopic view of four seasons of ice export out south through channels in the Canadian Arctic Archipelago (ie the CAA garlic press). The dates run from 15 Sept to 30 Jan for the years shown CW as 2017-18 (UL), 2016-17 (UR), 2015-16 (LR) and 2014-15 (LL).

The easiest way to get oriented is by locating Banks Island. The view extends east to encompass Ellesmere Island, Nares Strait and Lincoln Sea. This type of visualization does bring four years into good position for visual comparison on simultaneous dates but that is offset by the possible confusion that reflections bring. The indexed color version in ICA2 has some advantages though it loses the literal image sense of the original

Note that despite noise in the satellite image brought by passing weather systems, the land and Greenland ice cap are quite stably presented over the four year time span.

The longer term significance of this export mechanism comes as the Northwest Passages open earlier and stay open longer. Once the ice is gone there, ice to the north in the Arctic Ocean proper experiences much less resistance to export through the open waters of the channels.

The Beaufort years that developed a long streamer parallel to the Alaskan coast are shown in chronological succession in the final 79 day movie ending on Jan 30th. These years do not include 2016-17 or 2012-13.

The final movie looks at the origin of Fram export for all eight years: it is predominantly from the Laptev and Kara but includes some central ice pack. (The TransArctic drift has not been operative since 2010.) The last four years are across the top; the previous four along the bottom ending in 2010-11 in lower right.

It might be worth considering changing admissible forum width to 720x720 to accommodate .mov, .avi .mp4 as that seems the standard dimension in this realm (though custom dimensions are possible provided both are even). Mpeg offers excellent compression of gifs but if another round of approximation is forced on it, there will be degradation of satellite image quality.
« Last Edit: February 01, 2018, 05:14:06 PM by A-Team »

paolo

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Re: Arctic Image of the Day
« Reply #1092 on: February 04, 2018, 10:22:23 PM »
good morning

A-Team

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Re: Arctic Image of the Day
« Reply #1093 on: February 04, 2018, 11:47:38 PM »
A 200 x 70 km block of ice in McClure Strait stuck its head out into the Beaufort on 14 Jan 2018 as the whole Arctic ice pack lifts off but then retreats. Much more rapid clearing of the CAA than in situ melting is thus possible through this popping up and shearing off mechanism. which would be followed by transport and subsequent oblivion in the Beaufort-Chukchi.

The significance would not so much be this block of ice but rather early opening of the garlic press to the south, indeed a Northwest Passage. This illustrates once again why decadal trending of global surface temperatures and static thermodynamic melt will get Arctic outcomes hopelessly wrong and in turn mis-time the feedbacks.
« Last Edit: February 05, 2018, 12:36:14 AM by A-Team »

FishOutofWater

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Re: Arctic Image of the Day
« Reply #1094 on: February 05, 2018, 05:14:41 AM »
That image shows pumping action which will drive fresh water from the Beaufort sea through the CAA. Even if the ice gets held up there is a sea surface height gradient that causes Arctic ocean water to flow towards the low SSH Labrador sea.

Niall Dollard

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Re: Arctic Image of the Day
« Reply #1095 on: February 06, 2018, 03:43:26 PM »
Worldview image of the Bering Sea with ice nearing the remote St. Matthew Island. Uninhabited, despite being 43rd largest island in the USA. 

Pmt111500

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Re: Arctic Image of the Day
« Reply #1096 on: February 09, 2018, 09:44:30 AM »
Thought I'd liven up the image thread with an image taken half an hour after and towards the sunrise cross the frozen lake  :P ::)  8)
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binntho

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Re: Arctic Image of the Day
« Reply #1097 on: February 09, 2018, 12:21:48 PM »
Where is this frozen lake? Nice picure btw.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Pmt111500

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Re: Arctic Image of the Day
« Reply #1098 on: February 09, 2018, 12:27:25 PM »
 
Where is this frozen lake? Nice picure btw.
Thanks and it's the lower half :D ;D . Some snow on top. Nearest lake to where I live.
« Last Edit: February 09, 2018, 12:38:05 PM by Pmt111500 »
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binntho

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Re: Arctic Image of the Day
« Reply #1099 on: February 09, 2018, 12:31:54 PM »
I may have missed something - but "half an hour after" what? And where?
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6