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Sleepy

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Re: What's new in Antarctica ?
« Reply #400 on: November 12, 2018, 12:40:31 PM »
Iceberg flux from Antarctica from 1976-2017
https://twitter.com/PixelMnM/status/1061696386897530880
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gerontocrat

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Re: What's new in Antarctica ?
« Reply #401 on: November 12, 2018, 12:45:24 PM »
Iceberg flux from Antarctica from 1976-2017
Is it that the record is more complete in later years or has activity increased?
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Re: What's new in Antarctica ?
« Reply #402 on: November 12, 2018, 01:32:59 PM »
They don't provide the source in their tweet as you are able to read above, I would suspect it's from Budge an Long though. The Antarctic Iceberg Tracking Database.
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vox_mundi

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Re: What's new in Antarctica ?
« Reply #403 on: November 14, 2018, 05:18:09 PM »
Discovery of High Geothermal Heat at South Pole
https://phys.org/news/2018-11-discovery-high-geothermal-south-pole.html

Scientists have discovered an area near the South Pole where the base of the Antarctic Ice Sheet is melting unexpectedly quickly. Using radar to look through three km of ice, the team found that some of the ice – covering an area that's twice the size of Greater London – appeared to be missing. The results are published this week in the journal Scientific Reports.



... The internal layer draw-down, supported by the highly-reflective bed, points to active and significant basal melting in this region.

... "The process of melting we observe has probably been going on for thousands or maybe even millions of years and isn't directly contributing to ice sheet change. However, in the future the extra water at the ice sheet bed may make this region more sensitive to external factors such as climate change."

Open Source: T. A. Jordan et al. Anomalously high geothermal flux near the South Pole, Scientific Reports (2018).
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Sleepy

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Re: What's new in Antarctica ?
« Reply #404 on: November 14, 2018, 09:24:45 PM »
"May" is an understatement.
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Thomas Barlow

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Re: What's new in Antarctica ?
« Reply #405 on: November 15, 2018, 04:02:35 AM »

Bernard

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Re: What's new in Antarctica ?
« Reply #406 on: November 17, 2018, 11:18:20 AM »
"Massive Antarctic iceberg spotted on NASA Operation IceBridge flight"
- NASA.
Before and after.
https://climate.nasa.gov/news/2827/massive-antarctic-iceberg-spotted-on-nasa-operation-icebridge-flight/?fbclid=IwAR3TS86kS9mXrAGJgFr7pBUIMloryjMVT5Vr2cLHH6iR3IbGSZQCVqac2To
Given the color of ice and melt water on the top image in this article, no wonder why this glacier is called PIG  ;D

sidd

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Re: What's new in Antarctica ?
« Reply #407 on: November 19, 2018, 08:46:19 PM »
Bronselaer et al. report on effect of increase ice melt from AIS on climate:

They find:

1)meltwater cools the southern hemisphere sufficiently to delay exceedance of tempertature targets by a decade
2)ITCZ and precip moves north,  enhanced drying of the Southern Hemisphere and reduced drying of the Northern Hemisphere
3)Increased subsea (deeper than 400m) warming aroung AIS increasing basal melt.

Unfortunately it seems CMIP6 does not include the effects discussed.

" The direct contribution from mass loss from the Antarctic Ice Sheet is already included in the IPCC assessments of future sea-level rise, although it is acknowledged to be highly uncertain in the fifth assessment report. However, the effect on climate is not included, and will not be in the upcoming CMIP6 experimental design. Similarly, the effects of meltwater from the Greenland Ice Sheet have so far not been considered, and
could lead to further changes in simulated future climate [Refs. 8,36]."

"Meltwater causes a reduction  in global atmospheric warming, delaying the realization of 1.5 °C and 2 °C warming by more than ten years; it drives a northward shift of the ITCZ, which results in reduced drying over Northern Hemisphere landmasses and enhanced drying in the Southern Hemisphere; and  it causes a large (up to 31%) increase in Antarctic sea-ice formation  relative to the pre-industrial period and an increase in subsurface  ocean warming around the Antarctic coast by a factor of four. Our results suggest that a feedback mechanism is in operation, whereby  the meltwater-induced subsurface warming leads to enhanced melting underneath ice shelves, potentially causing further meltwater-related climate effects. "

I notice Sergienko is an author. I attach fig 4. Paper is at doi: 10.1038/s41586-018-0712-z

coverage at

https://phys.org/news/2018-11-antarctic-atmospheric-sea.html

sidd

wdmn

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Re: What's new in Antarctica ?
« Reply #408 on: December 11, 2018, 02:22:17 AM »
Posted this in the Ice Apocalypse thread, but it belongs here too.

More Glaciers in East Antarctica Are Waking Up https://www.nasa.gov/feature/goddard/2018/more-glaciers-in-antarctica-are-waking-up

Quote
East Antarctica has the potential to reshape coastlines around the world through sea level rise, but scientists have long considered it more stable than its neighbor, West Antarctica. Now, new detailed NASA maps of ice velocity and elevation show that a group of glaciers spanning one-eighth of East Antarctica’s coast have begun to lose ice over the past decade, hinting at widespread changes in the ocean.

gerontocrat

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Re: What's new in Antarctica ?
« Reply #409 on: December 11, 2018, 12:12:52 PM »
Bronselaer et al. report on effect of increase ice melt from AIS on climate:

"Meltwater causes a reduction  in global atmospheric warming, delaying the realization of 1.5 °C and 2 °C warming by more than ten years; it drives a northward shift of the ITCZ, which results in reduced drying over Northern Hemisphere landmasses and enhanced drying in the Southern Hemisphere; and  it causes a large (up to 31%) increase in Antarctic sea-ice formation
sidd

All the scientists say increased melt from the AIS will cause / is causing an increase in Antarctic sea ice extent. Up to 2014 the data supported this. Since then the data does not. I posted this on the Antarctic Sea Ice extent thread. At this moment in time the sea ice in Antarctic is falling to bits.

Quote from: AbruptSLR

Quote
This defined layering of temperatures is exactly what is happening now around the Antarctic.

"The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface," said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England an author of the paper.
"At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers on Pine Island and Totten. It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.""

There is a consistent narrative -

AGW is causing land-based ice to melt faster, adding massive additional amounts of freshwater to the ocean surface.

You would think that cold surface water (also low salinity with a higher freezing temperature) would encourage sea ice freeze as winter approaches and discourage sea ice melt as summer commences. Since 1979 up to recently, there has been a slow but measurable increase in Antarctic sea ice extent (maximum extent in 2014). Hypothesis confirmed ?

BUT since then the opposite. Antarctic sea ice extent is in decline, not just at max and min but during the melt season. Temporary aberration? Or is something  extra going on?


ps :Found this post from Jim Pettit on an old Antarctic Thread

https://forum.arctic-sea-ice.net/index.php/topic,178.msg2754.html#msg2754

Quote
New paper explains the recent growth of Antarctic sea ice.
« on: March 31, 2013, 10:20:40 PM »

Nature Geoscience published a new study online today that I found very interesting. It sheds some more light on the reasons behind the seemingly paradoxical growth of Antarctic sea ice (Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion) From the abstract:

"Changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature. In contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded, with record extent in 2010. This ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling. Here we show that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion. Specifically, we present observations indicating that melt water from Antarctica’s ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves. Simulating these processes in a coupled climate model we find that cool and fresh surface water from ice-shelf melt indeed leads to expanding sea ice in austral autumn and winter. This powerful negative feedback counteracts Southern Hemispheric atmospheric warming. Although changes in atmospheric dynamics most likely govern regional sea-ice trends, our analyses indicate that the overall sea-ice trend is dominated by increased ice-shelf melt. We suggest that cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise.
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vox_mundi

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Re: What's new in Antarctica ?
« Reply #410 on: December 13, 2018, 03:18:58 AM »
Two Technicians Die at U.S. Research Station In Antarctica
https://mobile.reuters.com/article/amp/idUSKBN1OC02G

Two technicians performing maintenance at a U.S. research station in Antarctica died on Wednesday while working on a building that houses a generator for a nearby radio transmitter, the National Science Foundation (NSF) said.

The pair, both employed by Virginia-based subcontractor, PAE , which provides logistical support to the NSF-managed McMurdo Station in Antarctica, were found unconscious on the floor of the building after a helicopter pilot flying over the area saw what appeared to be smoke coming from the structure and landed to investigate.

The two technicians had been working on a fire-suppression system at McMurdo station on Ross Island,

Arlington, Virginia-based Pacific Architects and Engineers (PAE) is a subcontractor to Leidos, which bills itself as the prime contractor for the National Science Foundation's US Antarctic Program.
« Last Edit: December 13, 2018, 03:39:35 AM by vox_mundi »
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vox_mundi

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Re: What's new in Antarctica ?
« Reply #411 on: December 31, 2018, 08:12:31 PM »
Science Team Drills Into Mercer Subglacial Lake
https://salsa-antarctica.org/2018/12/28/3578/
https://earther.gizmodo.com/scientists-just-melted-a-hole-through-3-500-feet-of-ice-1831329404



After four days of troubleshooting components that sustained wear and tear from sitting through two winters on ice, the Subglacial Antarctic Lakes Scientific Access (SALSA) Drill Team began drilling the main borehole on the evening of December 23rd and reached the lake faster than expected at 10:30pm on December 26th with a borehole depth of 1084 meters. The drill team then reamed (smoothed and widened) the borehole so that instruments can be sent down.



The only other subglacial lake humans have drilled into—nearby Lake Whillans, sampled in 2013—demonstrated that these extreme environments can play host to diverse microbial life. Naturally, scientists are stoked to see what they’ll find lurking in Lake Mercer’s icy waters.

Now that the lake is open, the real fun has begun. The SALSA team is deploying a suite of instruments to study the lake, including a CTD (Conductivity, Temperature, Depth) probe that will assess temperature and provide details on the structure of the water column, and a remotely operated vehicle to take similar measurements away from the borehole and capture 4k video. Researchers will collect samples of water and microbial DNA, as well as ice from the top of the lake and sediment from the bottom.
« Last Edit: December 31, 2018, 08:27:31 PM by vox_mundi »
“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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Juan C. García

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Re: What's new in Antarctica ?
« Reply #412 on: January 14, 2019, 09:52:44 PM »
Quote
Ice loss from Antarctica has sextupled since the 1970s, new research finds

An alarming study shows massive East Antarctic ice sheet already is a significant contributor to sea-level rise
https://www.washingtonpost.com/energy-environment/2019/01/14/ice-loss-antarctica-has-sextupled-since-s-new-research-finds/?utm_term=.1ef083fa3e2b

Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

wdmn

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Re: What's new in Antarctica ?
« Reply #413 on: January 14, 2019, 11:53:09 PM »
"Every 360 billion tonnes = 1 mm of sea level rise."

Doesn't exactly sound frightening.

sidd

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Re: What's new in Antarctica ?
« Reply #414 on: January 15, 2019, 01:20:48 AM »
The paper referred to in the Post article is open access.

doi:10.1073/pnas.1812883116

sidd

Sebastian Jones

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Re: What's new in Antarctica ?
« Reply #415 on: January 15, 2019, 06:13:16 AM »
"Every 360 billion tonnes = 1 mm of sea level rise."

Doesn't exactly sound frightening.

Unless the rate of loss keeps doubling every 6 years or so.....

Gray-Wolf

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Re: What's new in Antarctica ?
« Reply #416 on: January 15, 2019, 10:17:26 AM »
Agreed Sebastian , it is the time period of doubling as things do start to move pretty quick a few 'doublings' down the line!

But this misses the point that this has been the 'Drip,Drip' losses prior to the start of 'Ice cliff Fracturing' denudation which will see mass losses shoot up overnight!
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wdmn

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Re: What's new in Antarctica ?
« Reply #417 on: January 15, 2019, 04:30:05 PM »
Let's assume the amount doubles every 6 years.

In the 30 years from 2017 to 2047 the cumulative melt would be 44.8mm or 4.48 cm, or 1.76 inches.

In the 60 years from 2017 to 2077 the cumulative melt would be 716.8mm or 71.6 cm, or 28.2 inches, or 2 feet 4.2 inches.

So from 2017 to 2047 sea levels would rise (from Antarctica alone) 1.76 inches, and from 2047 to 2077 sea levels would rise 2 feet 2.44 inches. That's quite a dynamic second 30 years.

This would require the collapse of the WAIS beginning around mid-century.

Stephan

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Re: What's new in Antarctica ?
« Reply #418 on: January 15, 2019, 08:26:56 PM »
Thank you for doing this calculation. :)

Sebastian Jones

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Re: What's new in Antarctica ?
« Reply #419 on: January 17, 2019, 07:34:41 AM »
Thank you for doing this calculation. :)
Yes, and it lines up neatly with ASLR's projection that the WAIS will start to disintegrate in the 2050s.

Adam Ash

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Re: What's new in Antarctica ?
« Reply #420 on: January 17, 2019, 10:17:57 AM »
But isn’t the big fear the Great Discontinuity, where a whole lot of ice areas begin similtaneous sudden collapse?  Put two ice cubes in a box. Does one melt first then the other?  No. There is a thermal link which sees both melt at similar rates.  Doesn’t out atmospheric and oceanic circulation provide that same linkage, ensuring that most land-fast ice approaches the point of strucural failure at about the same time? 

mitch

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Re: What's new in Antarctica ?
« Reply #421 on: January 17, 2019, 04:56:24 PM »
"...But isn’t the big fear the Great Discontinuity, where a whole lot of ice areas begin similtaneous sudden collapse?  ..."

While it is of significant concern about how fast sea level might rise, the other big fear is that we start something that will continue for centuries and has a large net sea level increase.  Best estimates for Pliocene sea level, the last time CO2 was around 400 ppm,  are around 20 m higher than modern. 

Stephan

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Re: What's new in Antarctica ?
« Reply #422 on: January 17, 2019, 07:52:09 PM »
"...But isn’t the big fear the Great Discontinuity, where a whole lot of ice areas begin similtaneous sudden collapse?  ..."

While it is of significant concern about how fast sea level might rise, the other big fear is that we start something that will continue for centuries and has a large net sea level increase.  Best estimates for Pliocene sea level, the last time CO2 was around 400 ppm,  are around 20 m higher than modern...
...which would cause probably one billion refugees who will look for another place to live and who can not be sent back to their original countries/areas because these will be then completely inundated.

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #423 on: January 18, 2019, 09:38:51 AM »
Can someone tell me what is happening here in the Amery Ice Shelf?

Huge water ponds are forming despite the low temperatures (well below zero) on a white underground (low heat absorbing). Is this water coming from the mountains around?


sidd

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Re: What's new in Antarctica ?
« Reply #424 on: January 18, 2019, 10:06:09 AM »
I think those ponds have formed in years past, they are meltwater possibly from foehn winds.

Amery is one i watch closely. The thing is a dagger pointed into the heart of Antarctica. The danger is in the bed. The ice behind it has concave profile in elevation view as i have posted before, which has significance.

https://forum.arctic-sea-ice.net/index.php/topic,263.msg40975.html#msg40975

Amery disturbs me. When that shelf breaks up ...

sidd
« Last Edit: January 18, 2019, 10:13:35 AM by sidd »

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #425 on: January 18, 2019, 10:41:18 AM »
I think those ponds have formed in years past, they are meltwater possibly from foehn winds.

Amery is one i watch closely. The thing is a dagger pointed into the heart of Antarctica. The danger is in the bed. The ice behind it has concave profile in elevation view as i have posted before, which has significance.

https://forum.arctic-sea-ice.net/index.php/topic,263.msg40975.html#msg40975

Amery disturbs me. When that shelf breaks up ...

sidd

Thanks for your answer Sidd. Down the rabbit-hole i go... ;)


FredBear

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Re: What's new in Antarctica ?
« Reply #427 on: January 18, 2019, 12:50:58 PM »
Amery often grows large melt pools in January, with blue tints to the surrounding slopes (but snow reduces these signs, often starting by about Feb. 10?).
The most melt was visible in 2004-6, 2015, 2017 and this year, so is quite variable.
The front of the glacier has been advancing with no major calving for years.

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #428 on: January 18, 2019, 02:15:54 PM »
Thank you FredBear,

i've seen the ponds in recent years as you pointed out, but this year they seem to grow at a higher rate (?). I've also seen one article mentioning it was very big in 1988. I've also seen them getting brighter over time in recent years. The blue tint fades which i interpret as freezing again (at least on the surface).

I'm failing in finding an article that tells me how this is happening. I would like to know the physics behind this because in freezing temperatures at a high albedo (fresh)water should not just melt, right?

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #429 on: January 18, 2019, 02:21:35 PM »
On the other hand i find a lot of info about how this is an implication for how the ice sheet might behave in the future.

Tealight

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Re: What's new in Antarctica ?
« Reply #430 on: January 18, 2019, 07:58:39 PM »
I'm failing in finding an article that tells me how this is happening. I would like to know the physics behind this because in freezing temperatures at a high albedo (fresh)water should not just melt, right?

Melting snow and ice below freezing is nothing extraordinary at molecular level.

Melting snow and ice is all about breaking bonds between water molecules. At 0°C and standard atmospheric pressure the individual molecules move or vibrate so much around that existing bonds break and not enough new bonds can form. Temperature is just a description of the average movement of the molecules. Some move faster and some move slower than the average. During noon the slopes of the Amery ice shelf get to around -5°C so not very far off from 0°C. Depending on the slope angle the surface also get's blasted with 700-1000W/m2 (during noon)  of electromagnetic radiation from the sun which further increases the movement of molecules.

Albedo is just an average of reflected vs absorbed energy for all molecules in an area. A single molecule doesn't have an albedo value. Either it get's hit and absorbs the photon's energy (followed by a quick re-release of the energy with a lower energy photon) or the photon misses the molecule.

On a macro level snow can get down to an albedo of 50%, meaning it absorbs 300-500W/m2 while only losing maybe 100-200W/m2 to the below freezing air.


b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #431 on: January 18, 2019, 08:12:39 PM »
Thank you so much Tealight!

Yeah, makes sense. Looks like until now i haven't understood the albedo effect correctly. Need to read up on that.  ;D

vox_mundi

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Re: What's new in Antarctica ?
« Reply #432 on: January 18, 2019, 09:32:38 PM »
Report: Evidence of Life Found in Lake Deep Beneath Antarctic Ice
https://gizmodo.com/report-evidence-of-life-found-in-lake-deep-beneath-ant-1831870240

Scientists have found the bodies of tardigrades, algae, diatoms, and small crustaceans in a body of water buried beneath over a kilometer of Antarctic ice, according to a news report from Nature.

The results come from the Subglacial Antarctic Lakes Scientific Access (SALSA) project, which had previously announced that it would explore the water, called Lake Mercer, with a 60-centimeter-wide drill.

The carcasses originated from either 10,000 or 120,000 years ago during warming periods, after which ice smothered the lake again, according to Nature. It’s unclear how the life, particularly the land-dwelling, microscopic tardigrade and a certain fungus, got down there. But it’s thought that they subsisted on bacteria in the water.

The expert confirmed that the organisms looked like they’d been dead for thousands of years and that they were similar to ones found in some of Antarctica’s glacier-free regions
“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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steve s

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Re: What's new in Antarctica ?
« Reply #433 on: January 19, 2019, 05:17:27 AM »
There is another factor in the formation of melt ponds: snow absorbs near infrared better than visible frequencies, but both penetrate the surface. Thus, even if the surface is kept below freezing, the temperature just below the surface can reach freezing with melting beginning there. That melting darkens the snow and changes the albedo. Then a broader spectrum is absorbed, increasing the melt, as discussed by Tealight.

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #434 on: January 19, 2019, 06:56:35 AM »
Thank you Steve,

that's interesting! Didn't know about infrared getting absorbed better.