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oren

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Re: What's new in Greenland?
« Reply #350 on: November 16, 2018, 06:25:56 PM »
The Wikipedia link Tor provided is very informative, and I found the criticism section quite useful.

gerontocrat

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Re: What's new in Greenland?
« Reply #351 on: December 01, 2018, 05:17:29 PM »
A map - of the position of the main Greenland glacier fronts. I can never remember them all (easily confused at my age).

Also posted on Arctic Maps
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oren

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Re: What's new in Greenland?
« Reply #352 on: December 01, 2018, 08:11:29 PM »
Have you seen the Greenland map Espen once posted, with hundreds of named glaciers?

gerontocrat

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Re: What's new in Greenland?
« Reply #353 on: December 01, 2018, 08:13:26 PM »
Have you seen the Greenland map Espen once posted, with hundreds of named glaciers?
Nope - perhaps I will search for it. Too many glaciers!
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oren

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Re: What's new in Greenland?
« Reply #354 on: December 01, 2018, 09:04:39 PM »
Actually I just recalled it's in the sticky thread in this very sub-forum. "Google Maps with place names Greenland." It was started by Espen, but the map was posted by A-Team a bit down the thread.

gerontocrat

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Re: What's new in Greenland?
« Reply #355 on: December 01, 2018, 10:03:14 PM »
Actually I just recalled it's in the sticky thread in this very sub-forum. "Google Maps with place names Greenland." It was started by Espen, but the map was posted by A-Team a bit down the thread.
Found it. Almost impossible to read the names, but the really interesting thing is showing the velocity of movement that also shows up the catchment area of each glacier and where they merge into the main ice sheet..

What a big beast in the North East.
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litesong

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Re: What's new in Greenland?
« Reply #356 on: December 02, 2018, 04:38:27 AM »
Found it. Almost impossible to read the names
click on the map.... then select VIEW on the bar at the top of the screen.... pump the ZOOM UP. Makes the print a bit more readable.

sidd

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Re: What's new in Greenland?
« Reply #357 on: December 05, 2018, 10:06:29 PM »
Very nice paper by Trusel et al. on the acceleration in GIS melt beginning at the start of the Industrial Revolution. I see that Fettweiss is an author.

"Our results show a pronounced 250% to 575% increase in melt intensity over the last 20 years, relative to a pre-industrial baseline period (eighteenth century) ..."

"rates of meltwater production, refreezing and runoff across much of Greenland are all at multi-century highs ...

"The onset of industrial-era Arctic warming occurred in the mid-nineteenth century [21] and differential smoothing analysis likewise indicates increases in GrIS runoff initiated shortly thereafter (Fig. 4b; Methods). The median onset of positive trends in GrIS runoff are also coincident with the median onset of weakening Atlantic meridional overturning circulation [9] . Emergence of runoff beyond the natural range of variability, however, has only very recently occurred ..."

"Today, surface melting and melt-induced runoff in Greenland occur at magnitudes not previously experienced over at least the last several centuries, if not millennia."

I attach figs 4a,c. The latter illustrates the extreme nonlinearity of surface melt increase  with temperature. The thing is going to melt in place.

doi: 10.1038/s41586-018-0752-4

coverage at

https://phys.org/news/2018-12-greenland-ice-sheet-centuries.html

sidd

gerontocrat

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Re: What's new in Greenland?
« Reply #358 on: December 05, 2018, 10:53:42 PM »
Very nice paper by Trusel et al. on the acceleration in GIS melt beginning at the start of the Industrial Revolution. I see that Fettweiss is an author.

"Our results show a pronounced 250% to 575% increase in melt intensity over the last 20 years, relative to a pre-industrial baseline period (eighteenth century) ..."

"rates of meltwater production, refreezing and runoff across much of Greenland are all at multi-century highs ...

"The onset of industrial-era Arctic warming occurred in the mid-nineteenth century [21] and differential smoothing analysis likewise indicates increases in GrIS runoff initiated shortly thereafter (Fig. 4b; Methods). The median onset of positive trends in GrIS runoff are also coincident with the median onset of weakening Atlantic meridional overturning circulation [9] . Emergence of runoff beyond the natural range of variability, however, has only very recently occurred ..."

"Today, surface melting and melt-induced runoff in Greenland occur at magnitudes not previously experienced over at least the last several centuries, if not millennia."

sidd
There is a caveat. It is no surprise that summer melt is going up. But the melt happens in the brief Greenland Summer - June July & August. Surface Mass increases during the other 9 months - snow. The average net addition to mass in a year (Snow less melt - SMB) is about 400 GT. But calving exceeds this by about 200GT per annum

The prediction is for snow to increase at high latitudes due to increased water vapour due to AGW. In the last two years this has been the case. Quote from NSIDC's Greenland Today:-
Quote
The net change in (2018 mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade.

So melt in summer is just one of the three factors determining net loss of mass from the GIS.

When the new GRACE follow-on satellites starts to give us Greenland's mass change data again (hopefully from January 2019) we will know the extent to which the GIS is dumping ice into the sea.
links:-
http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/
https://nsidc.org/greenland-today/
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bbr2314

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Re: What's new in Greenland?
« Reply #359 on: December 06, 2018, 01:26:08 AM »
It is interesting that the major spike in Greenland runoff was concurrent precisely with the collapse of the Soviet Union. This was presaged by a lull back below trendline as well. I would posit that the abundance of SO2 was responsible for this dramatic shift -- as local atmospheric concentrations rose during and after WWII, we saw runoff nearly come to a halt. But by 1980, as economic disruptions began worsening in the USSR, SO2 emissions began to plunge. While the US / others also emit SO2, perhaps Soviet emissions were more important to Greenland due to relative proximity (Greenland is technically downwind of Siberia in a stable three-cell scenario making its emissions more important for localized effect of SO2).

Clearly other things are at play (Beaufort Gyre release etc) but the sharp drawdown in USSR emissions coincides precisely with the massive spike in meltwater. Not only did economic activity fall during this period, but evidently "trapping" of emissions also began.


FredBear

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Re: What's new in Greenland?
« Reply #360 on: December 06, 2018, 10:56:07 AM »
BBR, SO2 from Russia hardly "plunged" from 1981-88, more like 10% reduction in the figures. Helpful but unlikely to stop acid rain?

P-maker

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Re: What's new in Greenland?
« Reply #361 on: December 06, 2018, 04:11:37 PM »
Lurk,
Why don't you check your sources. The original Nature paper says a geothermal heat flux of 93 mW per sq. m., whilst the popular version talks about 100 MW per sq. m. I know it may not seem important to you, but to some,  m&M may make a difference.

bbr2314

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Re: What's new in Greenland?
« Reply #362 on: December 06, 2018, 06:25:03 PM »
BBR, SO2 from Russia hardly "plunged" from 1981-88, more like 10% reduction in the figures. Helpful but unlikely to stop acid rain?
A much larger % was captured during this time as well. SO2, besides causing acid rain, reduces incoming solar insolation and temperatures. Maybe the global reduction was to blame? I know the US was also cleaning up during the 80s but would assume "clean-up" was more effective in USSR due to its economic meltdown (i.e., less SO2 emitting activity in general).

P-maker

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Re: What's new in Greenland?
« Reply #363 on: December 07, 2018, 01:15:18 PM »
Lurk,

I guess my question really is: why pull out a couple of > 10 months old pieces of conflicting evidence in this thread?

I'm not blaiming anyone, just asking a simple question:

Are you being paid for sowing confusing seeds in the various Neven seedbeds?


oren

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Re: What's new in Greenland?
« Reply #364 on: December 07, 2018, 01:28:29 PM »
Are you being paid for sowing confusing seeds in the various Neven seedbeds?
I am not known to agree with Lurk much but I protest the slanderous insinuation.

Neven

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Re: What's new in Greenland?
« Reply #365 on: December 07, 2018, 01:57:01 PM »
I haven't followed this discussion. P-maker, how exactly is Lurk causing confusion, either intentional or unintentional?
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P-maker

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Re: What's new in Greenland?
« Reply #366 on: December 07, 2018, 02:33:23 PM »
Neven,
Lurk made a comment based on a solid German Nature-paper, which was published in July 2018. He then pulls in another Nature-paper from January, which is based on temperature observations made in another fjord located about 200 km N of the 79N glacier. In his post he makes  assumptions about variations in geothermal heatflux may be a contributing factor in the 79N glacier demise. Scale, cause, variability, distance and processes are completely out of whack. Call it intentional or not. I simply don't get it. Just to confuse things even more, he also deliberately pulls in an error-ridden popular version of the January paper. And then in his reply to me has the nerve to blame the editor of Science Daily for not catching an error made in the Press release from Aarhus University.
Cheers P

Neven

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Re: What's new in Greenland?
« Reply #367 on: December 07, 2018, 04:57:58 PM »
Hmmm, sounds to me like you're being a bit too much on the alert.

Quote
In his post he makes  assumptions about variations in geothermal heatflux may be a contributing factor in the 79N glacier demise.

Yes, well, so do the authors of the Mayer et al. paper:

Quote
However, the reason for the large interannual fluctuations of
the thinning rates revealed by this study still need to be found

(...)

Thus, while our
analysis suggests that the ocean is likely the main driver of the
observed changes at 79 North Glacier, the regional dynamics that
control the heat transport into the ice shelf cavity and other
contributors, such as subglacial discharge induced by surface melt
or geothermal heat flux will need further attention to fully
understand the observed thickness evolution.

So, Lurk posts links to a paper on exactly that subject:

Quote
Hence, this part of Greenland may play a role for the rapid basal melt located at the head of the Northeastern Greenland ice stream and its high ice speeds. In addition, the newly discovered 52 hydrothermal vent complexes13, some of which reach up to 11 km in diameter, in the Danmarkshavn Basin and in the Thetis Basin is located just outside the ice-stream outlet glaciers; Nioghalvfjersbræ, Zachariæ Isstrøm and Storstrømmen (Fig. 5). These complexes are formed from hot intrusions (c. 1200 °C) at 1–2 km depth in the Thetis Basin and >3 km depth in the Danmarkshavn Basin. Hence, this accumulated evidence point to active geothermal activity in the northeastern corner of Greenland and indicate that geothermal heat source may exist below the center and northeastern part of GIS. This heat source may explain the origin of the Northeast Greenland ice stream and other areas with high ice stream speed.

Maybe it's me, but I don't see anything wrong with 'making assumptions about variations in geothermal heatflux may be a contributing factor in the 79N glacier demise'.

As for the m&M stuff: Lurk didn't even mention these numbers in his comment, and he's most certainly not responsible for mistakes made by the people writing the press releases, especially as he linked directly to the paper itself. Maybe he didn't even notice it (I wouldn't have).

Quote
And then in his reply to me has the nerve to blame the editor of Science Daily for not catching an error made in the Press release from Aarhus University.

But you have the nerve to blame Lurk for it.  ::)

Come on, this makes no sense. Don't be paranoid.
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gerontocrat

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Re: What's new in Greenland?
« Reply #368 on: December 08, 2018, 08:46:38 PM »
Interesting paper on Greeland's tidewater glaciers suggesting a warmer ocean is going to accelerate calving by a lot.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL080763
Localized Plumes Drive Front‐Wide Ocean Melting of A Greenlandic Tidewater Glacier
Quote
Abstract
Recent acceleration of Greenland's ocean‐terminating glaciers has substantially amplified the ice sheet's contribution to global sea level. Increased oceanic melting of these tidewater glaciers is widely cited as the likely trigger, and is thought to be highest within vigorous plumes driven by freshwater drainage from beneath glaciers. Yet melting of the larger part of calving fronts outside of plumes remains largely unstudied. Here we combine ocean observations collected within 100 m of a tidewater glacier with a numerical model to show that unlike previously assumed, plumes drive an energetic fjord‐wide circulation which enhances melting along the entire calving front. Compared to estimates of melting within plumes alone, this fjord‐wide circulation effectively doubles the glacier‐wide melt rate, and through shaping the calving front has a potential dynamic impact on calving. Our results suggest that melting driven by fjord‐scale circulation should be considered in process‐based projections of Greenland's sea level contribution.

Plain Language Summary
As the world warms, loss of ice from the Greenland Ice Sheet will be a significant source of sea level rise. Greenland loses ice partly through the flow of huge rivers of ice called tidewater glaciers that dump solid ice directly into the ocean. Over the past two decades, tidewater glaciers around Greenland have accelerated dramatically, increasing Greenland's contribution to global mean sea level. There is mounting evidence that these accelerations have been driven by ocean warming, and a resulting increase in the rate at which the ocean melts the front of tidewater glaciers (called submarine melting). Yet submarine melting is at present poorly understood, in part due to the danger and difficulty of collecting data close to tidewater glaciers. We present observations of the ocean in front of a tidewater glacier that are unprecedented in their proximity to the glacier. These data reveal an ocean circulation which flushes warm water along the front of the glacier, driving high rates of submarine melting. We then use a numerical model to identify what drives this circulation. Our results are an important step toward understanding a key process which will modulate future sea level contribution from the Greenland ice sheet.
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P-maker

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Re: What's new in Greenland?
« Reply #369 on: December 08, 2018, 11:23:29 PM »
Neven,

I appreciate you take the time to read through the papers. In the Rysgaard et al thing they assumed the heating of the bottom of the fjord water could have been caused by a constant geothermal heat flux of 93 mW per sq. meter.

Lurk was using this number - remember we are talking milli Watts here - in an attempt to explain inter-annual variations in vertical thinning of the 79N glacier of up to 12 meter of solid ice in one single year.

Geothermal heat flux is for most practical purposes considered a constant, in particular if it comes from an Eocene intrusion som 55 mio. years ago. I do  acknowledge that hot spots under the ice may contribute to higher rates of bottom melt, but I would never have thought that this should ever be able to cause inter-annual variations in the mass loss from a floating ice shelf, which has lost about a third of its thickness over the past 20 years.

I could think of many other - more likely - factors affecting the inter-annual variation in ice loss from the 79 N glacier snout. Most likely - but also difficult to measure - is the advection of warmer waters from the Greenland Sea. Less likely, but it may still be found relevant, if measurements were available, would be inter-annual variability in sublimation rates. New evidence from Antarctica have in recent years addressed this issue in som detail, but I fear it will lead too far to go into more details here.

i will rest my case for the time being.

oren

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Re: What's new in Greenland?
« Reply #370 on: December 09, 2018, 11:17:08 AM »
Lurk is right, and the accusation very puzzling.

P-maker

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Re: What's new in Greenland?
« Reply #371 on: December 09, 2018, 12:05:34 PM »
Lurk & Oliven - you are quite a couple - the two of you!

By all means, carry on posting "news" like you have done in this particular thread, but please read the articles you intend to "flag" before you hit the keyboard. Self control is also about keeping the "noise level" down to the benefit of both yourselves and the remaining followers of this fine forum.

Have a nice Sunday!

gerontocrat

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Re: What's new in Greenland?
« Reply #372 on: December 09, 2018, 12:45:52 PM »
By all means, carry on posting "news" like you have done in this particular thread, but please read the articles you intend to "flag" before you hit the keyboard. Self control is also about keeping the "noise level" down to the benefit of both yourselves and the remaining followers of this fine forum.
I am sure we are all immensely grateful for your advice.

and that's all I am going to say about that
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oren

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Re: What's new in Greenland?
« Reply #373 on: December 09, 2018, 12:47:48 PM »
P-Maker, sorry if it feels I have ganged on you - not intended. I have clashed with Lurk several times in the past when he bullied other posters. I could do no less when an unfair accusation was leveled at him.

gerontocrat

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Re: What's new in Greenland?
« Reply #374 on: December 09, 2018, 01:04:01 PM »
A suggestion that life on land may have started even earlier

https://gizmodo.com/remnants-of-earths-oldest-dirt-may-have-been-found-in-g-1830342281

Remnants of Earth's Oldest Dirt May Have Been Found in Greenland
Quote
Earth’s oldest soil could be tucked away in an ancient rock outcrop in Greenland, according to new research. Dating back some 3.7 billion years, the suspected soil—exposed underneath a retreating ice cap—could potentially contain fossilized traces of primordial life.

The new study, published this week in the awkwardly named science journal Palaeogeography, Palaeoclimatology, Palaeoecology, opens thusly: “Soil formation is a combination of physical, chemical, or biological processes important for regulating planetary atmospheres, and the ultimate source of essential nutrients such as phosphorus for the nutrition and origin of life.”

Indeed, soil—unlike sterile bits of rock or sand—serves as a natural medium for the growth of land plants. Identifying our planet’s oldest soils, therefore, is of critical importance to scientists who study Earth’s formative period and the emergence of our planet’s first organisms.

The new study, led by University of Oregon geologist Greg Retallack and Old Dominion University geologist Nora Noffke, describes a tantalizing new rock outcrop in the Isua Greenstone Belt of southwestern Greenland that, quite possibly, contains our planet’s oldest dirt, and by consequence, the oldest traces of life on the planet.

It’s not actually dirt—it’s a substance known as paleosol, former soil that’s been packed tightly into solid rock.
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litesong

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Re: What's new in Greenland?
« Reply #375 on: December 11, 2018, 09:07:42 PM »
Remnants of Earth's Oldest Dirt May Have Been Found in Greenland[/b]
Earth’s oldest soil could be tucked away in an ancient rock outcrop in Greenland.....It’s not actually dirt—it’s a substance known as paleosol, former soil that’s been packed tightly into solid rock.
Would this paleosol have any analog to sandstones?

gerontocrat

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Re: What's new in Greenland?
« Reply #376 on: December 11, 2018, 09:33:47 PM »
Something to look out for. It looks like the gap in GRACE data will be a lot less than I thought.

https://arctic.noaa.gov/Report-Card/Report-Card-2018/ArtMID/7878/ArticleID/781/Greenland-Ice-Sheet
Quote
Total Ice Mass Balance
GRACE satellite data can be used to estimate monthly changes in the total mass of the Greenland ice sheet, as done in the past (e.g., Tedesco et al., 2017). However, the NASA GRACE mission, which started in 2002, ended in October 2017. Hence, there are no data available on the total mass balance for the 2017/18 season. The GRACE Follow On (GRACE-FO, https://gracefo.jpl.nasa.gov/) mission was launched on 22 May 2018. Data acquired since its launch are currently under review for quality control. The May 2018 launch means that no data are available from space between October 2017 and May 2018. Processing of the GRACE-FO dataset will provide estimates of total mass change anomalies for the summer of 2018 and will be calibrated to data acquired by GRACE.
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gerontocrat

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Re: What's OLD in Greenland?
« Reply #377 on: December 14, 2018, 10:49:02 AM »
This is an annex to the paper "Climatic variations in historic and prehistoric time" By Otto Petersson published in 1912 in UR Svenska Hydrografisk-Biologiska Kommisionens Skrifter
(http://www.mitosyfraudes.org/calen12/petterson_1.html)

It is "The ice conditions and climatic variations in Greenland" http://www.mitosyfraudes.org/calen12/petterson_2.html

I wonder if today's scientists look at these old papers to see if there is data locked way in dusty archives that could throw some light on history, or whether is is all dismissed as irrelevant old stuff.

It begins as follows...

Quote
Even in the age of the Sagas and the Vikings there existed an ice-bearing current on the east and northeast coasts of Greenland. But the current in those days cannot be compared to the present one, neither in extent nor in its importance to navigation. This fact I attribute to a more vivid circulation in the Irminger Sea in former days. According to the researchers of the Danish Ingolf expedition, the bulk of the Gulfstream branch known as the Irminger current turns westward at the entrance to the Denmark Strait and runs along the east coast of Greenland forming the underlayer of the ice-bearing polar current. According to Hambergs investigation in 1883 this warm underlayer melts the ice of the polar current and the amount of drift-ice on the eastcoast of Cape Dan in lat. 65 1/2º will vary with the strength of the Irminger current. South of Cape Farewell the ice turns west and northwest collecting outside the sosuthwestern coast of Greenland (Juliane-haabs Distrikt). Here 8-9 centuries ago the Icelandic colonists found an open sea. Now it is blocked by ice all summer because the Irminger current is too weak to melt de ice before it reaches Cape Farewell.

A small increase in the temperature of the under layer, or a stronger influx of Gulf stream water, or a stronger oscillation in the border-stratum causing a more vivid contact of the waters of the two currents would scatter the drift-ice so that the neighbourhood of Cape Farewell would be free from ice and the deep sounds between that island and the main land open to navigation. Later we shall see the importance of these sounds for the journeys of the Viking-settlers.

The formation of the coast in the lat. of Cape Dan causes the drift-ice to scatter after the passage of the Denmark Sound. The scattering of the ice and the action of the Irminger current which still in its full force crosses over from Iceland to Greenland makes the neighbourhood of Angmangsalik (Cape Dan) more accessible from the east than the southernmost point of Greenland<./p> Nordenskiöld was the first in modern time to profit by this when in 1883 he broke through the thin ice-layer outside Cape Dan and anchored his ship "the Sophia" in King's Oscar's harbour. (lat. 65º 35'). The stronger development of the Irminger current a thousand years ago brought two important consequences:

1. The climate of Österbygden (the eastern settlement) was more temperate because the sea coast was free from ice, whereas the district of Julianehaab has an ice-bound sea in front and the inland-ice behind.

2. As the ice did not go round Cape Farewell and enter Davis Strait, Baffin Bay and the Labrador-current were also relatively free from ice. This again influenced the climate of New Foundland and North America. It is also probable that the warm under current which runs through Davis Strait, like the Irminger current and the rest of the western Gulf stream-branches, was otherwise developed in those days. In other words: that the polar ice then melted at higher latitude than now.

At the end of the Middle-ages a change came in these conditions, which can only be explained by an alteration in the oceanic circulation. Such changes in the oceanic circulation will of course be more perceptible in the border-areas where the waning Gulf stream branch contents with currents of the northern origins as in Cattegat, the Baltic, Baffin Bay and at the south-point of Greenland. It is inconceivable that a state of equilibrium lasting through thousands of years should exist in those parts. Even now the conditions, especially the ice conditions, vary greatly from year to year in these seas. In Greenland there are good ice-years and bad ones. Now I will show the conditions in south Greenland in a good year like 1883 when Nordenskiöld on the Sophia landed at Fredriksdal and penetrated into the sounds north of Cape Farewell which had not been navigated by European ships since the days of the Vikings. Then I will give an instance of the conditions and the route of navigation in a bad year like 1902 as described by the Danish archeologist Captain Bruun.

Finally I will draw a comparison between these conditions and those which prevailed a thousand years ago when Iceland and Greenland were colonized and the Norsemen discovered America. In our time the east coast of Greenland from 65º lat. to Cape Farewell is almost inaccessible.
In good years the pack-ice may form a narrow belt along the coast. But the pressure of this ice-girdle, which is packed close to the coast whenever the wind blows in that direction, is almost more formidable to navigators than in bad years when the ice spreads for miles over the sea but generally leaves an open channel along the shore. This channel was used by the Danish expeditions under Graah, Holm and Garde o.a. Nansen too used this channel to get to the point from whence he started on his ice-wandering after he had landed on the drift-ice and carried his boats across it, just as they did in cases of emergency in ancient times, as is told in Kungaspegeln (the King Mirror) from the 13th century. Doubtless 600-700 years ago it was at times dangerous and even impossible to penetrate to the east coast of Greenland if it happened to be a bad ice-year.

But it must be remembered that in the Viking-age such years were exceptions and not the rule as is now the case. In spite of the strong tidal currents the sounds between Cape Farewell and the mainland are now always blocked by drift-ice which is crammed into their eastern inlets by the polar current outside. West of Cape Farewell there is the great fjord-district with the settlements of the ancient "Eystribyggd". All summer the Bay is blocked by drift-ice, and navigation is generally impossible till authum and then only by circuitous routes as shown by the dotted lines in the map of plate 11.

Circumstances being exceptionally favourable, Nordenskiöld was able to get to Julianehaab as early as the 17th June 1883. It is generally necessary to wait till late in summer and, working through the ice-girdle, make the coast by the northliest route through Nunarsiut Sound then go south-wards on an inner route along the coast of Julianehaab and Fredriksdal which is the farthest accessible settlement. From here the expeditions of Wallö, Giesecke, Graah, Holm and Garde in Eskimo boats penetrated through the sounds north of Cape Farewell: the Ikerasak, the Ikek, the Tunua, the Kipisak a. o. which, though never sounded, were found to be navigable up to their eastern inlets, where the ice of the polar current was encountered. In spite of the favourable conditions in 1883 Nordenskiöld had no better luck. He was turned back by the ice when trying to penetrate through the sounds and was unable to reach the east coast. Such are the conditions in a good ice-year. The ice-charts of 1903 and Captain Bruun's description of his journey to Greenland in the summer 1903 show how the navigation must be performed in a bad year.
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Klondike Kat

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Re: What's new in Greenland?
« Reply #378 on: December 14, 2018, 03:01:46 PM »
Very nice gerontocrat.

Do you know how conditions today compare to those in the past?

gerontocrat

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Re: What's new in Greenland?
« Reply #379 on: December 14, 2018, 10:07:08 PM »
Very nice gerontocrat.

Do you know how conditions today compare to those in the past?
The following article describes how the little ice age that was supposed to have driven away the Viking settlers from Greenland is a myth.

What is true that the remnants of those settlements are now melting away.

https://www.businessinsider.com/greenlands-melting-ice-exposes-ancient-artifacts-2016-10?r=US&IR=T
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johnm33

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Re: What's new in Greenland?
« Reply #380 on: December 15, 2018, 11:54:08 AM »
There was a Canadian academic who made quite a study of the Viking presence throughout the archipelago, mining on Axel Heiberg/Victoria/Banks as well as the west coast of Greenland. If I remember her name I'll find a link. For them to have been there suggests the archipelago was seasonally navigable. That it suddenly altered is suggested by the blond inuit tribe that was discovered and that equally suddenly long houses appeared down the Pacific coast. Iirc her findings were deemed too sensitive politically and she lost her funding.

sidd

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Re: What's new in Greenland?
« Reply #381 on: January 03, 2019, 08:18:38 AM »
Hard rain falling on Greenland:

"Both winter and summer events are associated with a south-southeasterly wind over the central and western parts of the ice sheet ... the southerly component of the winds is enhanced by a large-scale high pressure anomaly southeast of Greenland and a low pressure anomaly to the southwest  ... the southerly winds not only carry heat, but also moisture over the ice sheet, ... "

" ... that in both seasons, approximately half of the rain and melt associated with melt events runs off and the other half refreezes ..."

[Each gram of rain refreezing delivers 80 calories of heat to the ice sheet.]

"In winter, the rainfall also significantly increased ... "

"the observed increases in the occurrence and areal extent of the initiated melting have led to a more frequent replacement of snow by rain and a northward and upslope shift of the boundary between rain/melting and snowfall, thus changing the balance between Greenland’s mass gain and mass loss within a single weather event."

Read all about it. Open access:

https://www.the-cryosphere-discuss.net/tc-2018-243/https://www.the-cryosphere-discuss.net/tc-2018-243/

sidd

vox_mundi

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Re: What's new in Greenland?
« Reply #382 on: January 03, 2019, 02:43:10 PM »
Melting Ice Sheets Release Tons of Methane Into the Atmosphere
https://m.phys.org/news/2019-01-ice-sheets-tons-methane-atmosphere.html

Quote
The Greenland Ice Sheet emits tons of methane according to a new study, showing that subglacial biological activity impacts the atmosphere far more than previously thought.

... Professor Jemma Wadham, Director of Bristol's Cabot Institute for the Environment, who led the investigation, said: "A key finding is that much of the methane produced beneath the ice likely escapes the Greenland Ice Sheet in large, fast flowing rivers before it can be oxidized to CO2, a typical fate for methane gas which normally reduces its greenhouse warming potency."
...  With Antarctica holding the largest ice mass on the planet, researchers say their findings make a case for turning the spotlight to the south. Mr Lamarche-Gagnon added: "Several orders of magnitude more methane has been hypothesized to be capped beneath the Antarctic Ice Sheet than beneath Arctic ice-masses. Like we did in Greenland, it's time to put more robust numbers on the theory."

 Guillaume Lamarche-Gagnon et al. Greenland melt drives continuous export of methane from the ice-sheet bed, Nature (2018).
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kassy

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Re: What's new in Greenland?
« Reply #383 on: January 22, 2019, 01:34:59 PM »
Greenland ice melting four times faster than in 2003, study finds

...

Scientists concerned about sea level rise have long focused on Greenland's southeast and northwest regions, where large glaciers stream iceberg-sized chunks of ice into the Atlantic Ocean. Those chunks float away, eventually melting. But a new study published Jan. 21 in the Proceedings of the National Academy of Sciences found that the largest sustained ice loss from early 2003 to mid-2013 came from Greenland's southwest region, which is mostly devoid of large glaciers.

"Whatever this was, it couldn't be explained by glaciers, because there aren't many there," said Michael Bevis, lead author of the paper, Ohio Eminent Scholar and a professor of geodynamics at The Ohio State University. "It had to be the surface mass—the ice was melting inland from the coastline."

...

The key finding from their study: Southwest Greenland, which previously had not been considered a serious threat, will likely become a major future contributor to sea level rise.

...

Bevis' team used data from GRACE and from GPS stations scattered around Greenland's coast to identify changes in ice mass. The patterns they found show an alarming trend—by 2012, ice was being lost at nearly four times the rate that prevailed in 2003. The biggest surprise: This acceleration was focused in southwest Greenland, a part of the island that previously hadn't been known to be losing ice that rapidly.

Read more at: https://phys.org/news/2019-01-greenland-ice-faster.html#jCp
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vox_mundi

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Re: What's new in Greenland?
« Reply #384 on: February 11, 2019, 08:06:25 PM »
NASA Finds Possible Second Impact Crater Under Greenland Ice
https://www.eurekalert.org/pub_releases/2019-02/nsfc-nfp021119.php

A NASA glaciologist has discovered a possible second impact crater buried under more than a mile of ice in northwest Greenland.

His follows the finding, announced in November 2018, of a 19-mile-wide crater beneath Hiawatha Glacier - the first meteorite impact crater ever discovered under Earth's ice sheets. Though the newly found impact sites in northwest Greenland are only 114 miles apart, at present they do not appear to have formed at the same time.

If the second crater, which has a width of over 22 miles, is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.



... Following the finding of that first crater, MacGregor checked topographic maps of the rock beneath Greenland's ice for signs of other craters. Using imagery of the ice surface from the Moderate Resolution Imaging Spectroradiometer instruments aboard NASA's Terra and Aqua satellites, he soon noticed a circular pattern some 114 miles to the southeast of Hiawatha Glacier. The same circular pattern also showed up in ArcticDEM, a high-resolution digital elevation model of the entire Arctic derived from commercial satellite imagery.

To confirm his suspicion about the possible presence of a second impact crater, MacGregor studied the raw radar images that are used to map the topography of the bedrock beneath the ice, including those collected by NASA's Operation IceBridge. What he saw under the ice were several distinctive features of a complex impact crater: a flat, bowl-shaped depression in the bedrock that was surrounded by an elevated rim and centrally located peaks, which form when the crater floor equilibrates post-impact. Though the structure isn't as clearly circular as the Hiawatha crater, MacGregor estimated the second crater's diameter at 22.7 miles. Measurements from Operation IceBridge also revealed a negative gravity anomaly over the area, which is characteristic of impact craters.

"The only other circular structure that might approach this size would be a collapsed volcanic caldera," MacGregor said. "But the areas of known volcanic activity in Greenland are several hundred miles away. Also, a volcano should have a clear positive magnetic anomaly, and we don't see that at all."

Although the newly found impact craters in northwest Greenland are only 114 miles apart, they do not appear to have been formed at the same time. From the same radar data and ice cores that had been collected nearby, MacGregor and his colleagues determined that the ice in the area was at least 79,000 years old. The layers of ice were smooth, suggesting the ice hadn't been strongly disturbed during that time. This meant that either the impact happened more than 79,000 years ago or -- if it took place more recently -- any impact-disturbed ice had long ago flowed out of the area and been replaced by ice from farther inland.

Open Access: Joseph A. MacGregor et al. A Possible Second Large Subglacial Impact Crater in Northwest Greenland, Geophysical Research Letters (2019).


“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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gerontocrat

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Re: What's new in Greenland?
« Reply #385 on: March 08, 2019, 09:42:39 AM »
What's new in Greenland? Rain !- in Winter

https://www.bbc.co.uk/news/science-environment-47485847
Climate change: Rain melting Greenland ice sheet 'even in winter'

Quote
Rain is becoming more frequent in Greenland and accelerating the melting of its ice, a new study has found. Scientists say they're "surprised" to discover rain falling even during the long Arctic winter. Precipitation usually falls as snow in winter - rather than as rain - which can balance out any melting of the ice in the summer. 

What did the scientists find?
The scientists studied satellite pictures of the ice-sheet which reveal the areas where melting is taking place. And they combined those images with data gathered from 20 automated weather stations that recorded when rainfall occurred.

The findings, published in the journal The Cryosphere, show that while there were about two spells of winter rain every year in the early phase of the study period, that had risen to 12 spells by 2012. On more than 300 occasions between 1979-2012, the analysis found that rainfall events were triggering a melting of the ice. Most of these were in summertime, when the air often gets above zero.

But a growing number happened in winter months when the permanent dark of the polar winter would be expected to keep temperatures well below freezing.

What happens when it rains?

The lead author of the study, Dr Marilena Oltmanns of the GEOMAR ocean research centre in Germany, told BBC News: "We were surprised that there was rain in the winter. It does make sense because we're seeing flows of warm air coming up from the South, but it's still surprising to see that associated with rainfall."

Another scientist on the study, Prof Marco Tedesco of Columbia University in New York, said that the increase in rain had important implications. Even if it falls during winter, and then quickly refreezes, the rain changes the characteristics of the surface, leaving it smoother and darker, and "pre-conditioned" to melt more rapidly when summer arrives. The darker the ice is, the more heat it absorbs from the Sun - causing it to melt more quickly. "This opens a door to a world that is extremely important to explore," Prof Tedesco said. "The potential impact of changes taking place in the winter and spring on what happens in summer needs to be understood."

A smoother surface, particularly a "lens" of ice, will allow meltwater to flow over it much faster and being darker means that more of the Sun's rays are absorbed, further speeding-up the warming process.

What do other scientists make of this?
Prof Jason Box, a glaciologist not involved in the new study, says the research builds on earlier work by him and colleagues published in 2015 that found that summer rainfall could increase the rate of melting. Their analysis found that because water has a high heat content, it takes only 14mm of rain to melt 15cm of snow, even if that snow is at a temperature of minus 15C.

"There's a simple threshold, the melting point, and when the temperature goes above that you get rain instead of snow," he said."So, in a warming climate it's not rocket science that you're going to have more rain than snow, and it's one more reason why the ice sheet can go into deficit instead of being in surplus." Prof Box has himself experienced sudden rainstorms while camped on the ice-sheet. "After weeks of sunshine, it started raining on us and it completely transformed the surface - it got darker. "And I became convinced - only by being there and seeing it with my own eyes - that rain is just as important as strong sunny days in melting the Greenland ice sheet."

https://www.the-cryosphere.net/13/815/2019/
Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions
Quote
Conclusions
By combining remote-sensing-based melt extent data and observations from weather stations, we have shown that surface melt is triggered by cyclonic weather events in summer and winter. Through the advection of heat and moisture over large portions of the ice sheet, these events lead to increases in cloud cover, precipitation, an enhanced absorption of longwave radiation and decreases in the albedo in the south and near the coast. Previous studies have found that cyclonic rainfall events in late summer have accelerated the glacial flow (Doyle et al., 2015), suggesting that the identified melt events can also trigger dynamic instabilities in the ice sheet. Since the efficiency of the glacial flow was critically determined by the seasonal condition of the subglacial drainage system (Doyle et al., 2015), we mostly expect melt events in late summer to have this effect.

The strong, rapid and short-lived character of the temperature increase, the high wind speeds, the precipitation and their frequent occurrence, also excluding summer, distinguish the investigated cyclonic weather events from the anticyclones, centered over Greenland, that have previously been recognized as the main driver of surface melting (Overland et al., 2012; Fettweis et al., 2013; Hanna et al., 2013a, 2016). However, regarding the extended duration of melt events in summer, we surmise that the identified melt triggers can evolve into the previously described persistent high-pressure anomalies, which is supported by studies suggesting that particularly intense and long-lasting atmospheric blocking episodes in summer have been reinforced by cyclones that preceded them (Neff et al., 2014; McLeod and Mote, 2015).

The frequency, amplitude and duration of the initiated melt events have increased over the period 1988–2012, which is mostly attributed to rising air temperatures. In summer, the albedo feedback (Box et al., 2012) and enhanced atmospheric blocking (Hanna et al., 2016) likely contributed to prolonging their duration. While we did not observe a significant increase in the occurrence of the initial melt-triggering, cyclonic moisture intrusions, model projections suggest that they will become more frequent towards the end of this century (Schuenemann and Cassano, 2010). Since the investigated period included warming related to Atlantic multidecadal variability (Straneo and Heimbach, 2013), the temperature and melt event trends were particularly steep, and thus, their slope cannot be taken to be representative of future changes. Still, continuing warming as predicted by state-of-the-art global climate models (Stocker, 2014) is expected to amplify the melting associated with melt events.

A decomposition of the synoptic atmospheric variability over Greenland suggested that the identified, melt-triggering weather pattern has accounted for ∼40 % of the total precipitation. Yet, the observed increases in the occurrence and areal extent of the initiated melting have led to a more frequent replacement of snow by rain and a northward and upslope shift of the boundary between rain/melting and snowfall, hence changing the balance between Greenland's mass gain and mass loss within a single weather event. Using a regional climate model, we estimated that the melting associated with melt events more than doubled in summer and more than tripled in winter, amounting to ∼28 % of the overall melt. Thus, we conclude that, despite the involved mass gain, year-round precipitation events are contributing to the ice sheet's decline.
"Para a Causa do Povo a Luta Continua!"
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rboyd

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Re: What's new in Greenland?
« Reply #386 on: March 08, 2019, 04:40:53 PM »
In one of his videos, Paul Beckwith raised the possibility of greatly increased rains once the Arctic becomes ice free. His logic made sense to me (clear ocean being heated by the sun producing water vapour and a rising air mass exchanging with colder continents, including Greenland). This seems to be a possible significant feedback (both for Greenland ice melt and permafrost breakdown) - are there any scientific papers that have tried to model this?

Niall Dollard

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Re: What's new in Greenland?
« Reply #387 on: March 08, 2019, 09:24:47 PM »
What's new in Greenland? Rain !- in Winter

https://www.bbc.co.uk/news/science-environment-47485847

It's an interesting study. But it's a review of data over the period 1979 to 2012.

2012. That's now 7 years ago.

We frequently talk about how rapidly the climate of the Arctic is changing and I think in this era of supreme computing power and data analysis, publishing 7 year old data is just not good enough. Think about what has happened over Greenland in the 7 summers and winters since then.

What's new in Greenland ? Not to be found in this study.
« Last Edit: March 08, 2019, 10:44:11 PM by Niall Dollard »

Tor Bejnar

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Re: What's new in Greenland?
« Reply #388 on: March 08, 2019, 11:47:10 PM »
Also, 2012 was an extreme melt year (in Greenland and elsewhere, not matched since): not a good year to end trend calculations with (when viewed 7 years later).
Arctic ice is healthy for children and other living things.

Espen

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Re: What's new in Greenland?
« Reply #389 on: March 09, 2019, 12:20:09 PM »
Also, 2012 was an extreme melt year (in Greenland and elsewhere, not matched since): not a good year to end trend calculations with (when viewed 7 years later).
Depends on what the purpose of the study is?
Have a ice day!

gerontocrat

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Re: What's new in Greenland?
« Reply #390 on: March 09, 2019, 01:24:31 PM »
Also, 2012 was an extreme melt year (in Greenland and elsewhere, not matched since): not a good year to end trend calculations with (when viewed 7 years later).
Depends on what the purpose of the study is?
Purpose :" the mechanisms that trigger melt are still insufficiently understood"
Results:   "we show that melt is initiated by a cyclone-driven, southerly flow of warm, moist air, which gives rise to large-scale precipitation. " and..
"year-round precipitation events are participating in the ice sheet’s decline."
"Based on linear regression, we find that over these 25 (1988-2012)years, the number of winter events has risen from circa 2 to circa 12 in a single winter."

They also talk about how in Summer southerly cyclones (mostly from the SE) with associated precipitation often precede long periods of high pressure and sunny days.
They also look at how much of the rain and associated snow melt refreezes and how much runs off.

Perhaps that questions the assumptions used by the models used by NSIDC (Greenland) and DMI for the SMB calculations, especially given how much of precipitation in Greenland is concentrated in the warmer Southern and Eastern coastal fringes. (see image attached).

Quote
Abstract. Surface melting is a major driver of Greenland’s
mass loss. Yet, the mechanisms that trigger melt are still
insufficiently understood because seasonally based studies
blend processes initiating melt with positive feedbacks. Here,
we focus on the triggers of melt by examining the synoptic
atmospheric conditions associated with 313 rapid melt increases,
detected in a satellite-derived melt extent product,
equally distributed throughout the year over the period 1979–
2012. By combining reanalysis and weather station data, we
show that melt is initiated by a cyclone-driven, southerly flow
of warm, moist air, which gives rise to large-scale precipitation.

A decomposition of the synoptic atmospheric variability
over Greenland suggests that the identified, melt-triggering
weather pattern accounts for  40% of the net precipitation,
but increases in the frequency, duration and areal extent of
the initiated melting have shifted the line between mass gain
and mass loss as more melt and rainwater run off or accumulate
in the snowpack. Using a regional climate model, we
estimate that the initiated melting more than doubled over
the investigated period, amounting to  28% of the overall
surface melt and revealing that, despite the involved mass
gain, year-round precipitation events are participating in the
ice sheet’s decline.

_______________________________________________
ps: GRACE Follow-On - where are you? No info from NASA or Germany since late 2018. Is it in trouble as data was promised by now.

"Para a Causa do Povo a Luta Continua!"
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Tealight

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Re: What's new in Greenland?
« Reply #391 on: March 10, 2019, 06:47:44 PM »
As many of you know the DMI moved all their Greenland data products to the Polar Portal website (http://polarportal.dk/en/greenland/surface-conditions/)

I emailed them about the missing accumulated SMB map and their reply was that it isn't as popular as the anomaly map and therefore unlikely to make it over to PolarPortal. I find it dissapointing, but to brighten up my day I found their monthly raw data is freely available for research purposes. (currently Jan 1980 to Aug 2017)

So I think I produce the accumulated SMB maps myself all the way back to 1980 and create some long term SMB graphs (whole year Sep-Aug) and only the melt season (Jun-Aug). Is there anything you would like to see that's possible to create with monthly surface mass balance data?

gerontocrat

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Re: What's new in Greenland?
« Reply #392 on: March 10, 2019, 07:40:25 PM »
As many of you know the DMI moved all their Greenland data products to the Polar Portal website (http://polarportal.dk/en/greenland/surface-conditions/)

I emailed them about the missing accumulated SMB map and their reply was that it isn't as popular as the anomaly map and therefore unlikely to make it over to PolarPortal. I find it dissapointing, but to brighten up my day I found their monthly raw data is freely available for research purposes. (currently Jan 1980 to Aug 2017)

So I think I produce the accumulated SMB maps myself all the way back to 1980 and create some long term SMB graphs (whole year Sep-Aug) and only the melt season (Jun-Aug). Is there anything you would like to see that's possible to create with monthly surface mass balance data?
I am greedy, - "I want it all, and I want it now"

The location of accumulated SMB is important - including the winter build-up. The anomaly this year is telling me where accumulated SMB is below and above average, but is not telling me where and how much snow has fallen. Obviously up North and uphill is likely to melt later and less strongly. So my cry is for at minimum the end of winter (May 31) accumulated SMB map. It gives the starting point for melt. Having a contour map "watermark" imposed upon it would also give an idea of how much accumulated SMB vs chances of melt. And then of course all the trends, SD etc.

I told you I was greedy. It's your fault, Tealight - you did the NH Snow / Albedo project so damn quickly and comprehensively that we now expect you to enact the US "SeaBees" mantra -
"the difficult you get now, the impossible a little later".
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

mabarnes

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Re: What's new in Greenland?
« Reply #393 on: March 11, 2019, 01:51:56 PM »
LOL ... hope you get it...!    ::)

vox_mundi

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Re: What's new in Greenland?
« Reply #394 on: March 11, 2019, 10:17:37 PM »
Traces of Giant, 2,700-Year-Old Solar Storm Detected in Greenland Ice   
https://gizmodo.com/traces-of-giant-2-700-year-old-solar-storm-detected-in-1833205336

Evidence of an unusually strong solar storm that hit Earth in 660 BCE has been detected in Greenland ice cores—a finding which shows we still have lots to learn about these disruptive events.

An extreme form of solar storm, known as a solar proton event (SPE), struck our planet 2,679 years ago, according to new research published today in Proceedings of the National Academy of Sciences. If an event of such magnitude were to happen today, it would likely wreak havoc on our technological infrastructure, including communications and navigation. Lund University geologist Raimund Muscheler and his colleagues presented evidence in the form of elevated levels of beryllium-10 and chlorine-36 isotopes embedded within ancient Greenland ice cores.

It’s now the third massive SPE known to scientists, the others occurring 1,245 and 1,025 years ago. This latest discovery means solar storms of this variety are likely happening more frequently than we thought—perhaps once every 1,000 years—but more data is required to create more reliable estimates. 

https://www.pnas.org/cgi/doi/10.1073/pnas.1815725116
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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Phil.

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Re: What's new in Greenland?
« Reply #395 on: March 19, 2019, 02:52:42 PM »

_______________________________________________
ps: GRACE Follow-On - where are you? No info from NASA or Germany since late 2018. Is it in trouble as data was promised by now.

This is the latest I've seen:
"• November 01, 2018: The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission has resumed collecting science-quality data and planned in-orbit checks after successfully completing a switchover to a backup system in the microwave instrument (MWI) on one of the mission's twin spacecraft. The in-orbit checks include calibrations and other system tests, and are expected to continue until January, when GRACE-FO will enter the science phase of its mission. 34)

- "The new unit is performing as expected," said Frank Webb, GRACE-FO project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "The spacecraft are tracking each other and collecting science-quality data."

- Both GRACE-FO satellites are equipped with redundant systems in their MWIs, which are their primary measurement instruments. The MWIs very precisely measure the distance change between the two satellites.

- The switchover to the backup system was required after an anomaly occurred in a component of the primary system. The primary unit was powered down on 19 July, when an instrument fault monitor detected that it was using less current than expected. After a full investigation by an anomaly response team, the mission team began a series of procedures required to switch over to the new unit. The backup system in the MWI was powered up on 19 October."

b_lumenkraft

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Re: What's new in Greenland?
« Reply #396 on: March 22, 2019, 08:38:06 AM »
Beautiful pictures of Greenland in this video:

Greenland: The Land Of Ice Embracing Climate Change | ABC Foreign Correspondent


Tor Bejnar

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Re: What's new in Greenland?
« Reply #397 on: April 02, 2019, 04:52:49 PM »
New Icy Seas post by Andreas Muenchow:
How to whisper under sea ice: Wireless Acoustic Sensor Network Design
(most of article's first and last paragraphs below - lots of interesting paragraphs in between)
Quote
I want to build a cell phone system under water. I want it to send me a text messages every 30 minutes from 200 feet below the ocean that is covered by sea ice next to a glacier in northern Greenland where polar bears roam to catch seals for food at -40 Fahrenheit.

Subsequent analysis in 2017/18 revealed a successful experiment as data from ocean sensors traveled along multiple paths to the weather station and on to the internet. All data were submitted to the NSF Arctic Data Center where after review they will become public at

https://arcticdata.io/catalog/view/urn:uuid:f971cf25-ed73-412d-bd52-98f84b3845c0
Arctic ice is healthy for children and other living things.

Susan Anderson

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Re: What's new in Greenland?
« Reply #398 on: April 02, 2019, 09:28:13 PM »
I see a recent related post in "Ice Apocalypse" but since this one mentions Greenland in the title, I'll assume it's OK as a related cross-reference: http://www.rcinet.ca/eye-on-the-arctic/2019/04/01/ice-cliffs-sea-level-rise-study-greenland/
The original for both Antarctica and Greenland slumping research appears to be the same: https://pubs.geoscienceworld.org/gsa/geology/article/569567/ice-cliff-failure-via-retrogressive-slumping

Quote
Scientists have found that tall ice cliffs in Greenland are slumping — and this may eventually lead to a more rapid rise in sea levels.

The study, published this month in the journal Geology, suggests ice on glacial cliffs in Greenland and Antarctica are acting like soil and rock by slumping — which refers to when weakened sediment breaks apart from land and slides down a slope.

“It’s sort of like a human slumping down in an easy [recliner] chair,” said Richard Alley, one of the authors of the paper and a professor of geosciences at Pennsylvania State University.

Though most of you know this, Dr. Alley is a reliable source who doesn't tend to exaggerate.

Arima

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Re: What's new in Greenland?
« Reply #399 on: April 18, 2019, 11:07:02 AM »