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Jim Hunt

Thanks Neven,

Given the current rapid rate of area/extent decline I've even recently been speculating that the 2019 volume maximum may already be in place.

Can I safely assume that you're confident I'm due to consume another tasty slice of crow pie later this month?

Neven

Reasonably confident, Jim. :-D

But not 100%. It's too bad we don't get daily PIOMAS updates at this time of year.

wayne

That is an impressive Polarview picture Neven

I see the thinner ice from last summers open water anomaly, keep in mind, newer sea ice can break more easily than old. The arch is rather jammed with with broken up first year and Nares didn't transport as much MYI as it use too,
there was likely no ice jam causing it to freeze over....

AnotherJourneybyTrain

Zack Labe has March temperature 5th highest on record, but of course, his data is for 70N (whereas I use 65N). His temperature ranking graph shows how this winter has been good for sea ice temperature-wise:

<<
Um, typo?

Neven

November 2018: 12th
December 2018: 8th
January 2019: 17th
February 2019: 11th

Now compare this to the previous three winters. It's all relative.

gkoehler

NSIDC Charctic shows Arctic Sea Ice extent at record low for April 9, and at least a week ahead of retreat curve for next lowest years (2018, 2017, 2016, 2007).
https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

DMI 80+N temps. spiked last week and presumably accounts for most if not all of the nose dive in Arctic sea ice extent. But similar temperature spikes in the past in my recollection have not resulted in such a steep decline.

Climate Reanalzyer (CR) Arctic 2M temperature anomaly 10-day forecast vs 1979-2000 baseline ranges from +3.6 to +0.6C for Arctic as a whole, but the positive anomaly may be somewhat less over the sea ice area. These are moderate to low positive anomalies for the CR Arctic temperature.
https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2anom

That said, the DMI 1958-2002 average 80N temperature shows rapid increase at this time of year, so even a moderate positive anomaly may allow continued rapid decline in extent.

Countering/moderating info:
The sea ice volume is tracking near but about 4% above record low years for April 9 (2016,2017).
http://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-thickness-and-volume/
The CR 10-day cloud forecast is for almost continuous cloud cover.

Taken altogether, my amateur impression is that ASI extent is declining faster in response to warming input that in previous years. Or is it just packing together more?

On April 9, 2012, ASI extent was tracking with the the 1981-2010 mean, and ca. 1 million km2 above current value. Then 2012 ended up with dramatic new low Sept. minimum, in large part due to August storm. So ASI extent at this early date may have little if any predictive power for Sept. minimum.

I'm wondering how folks with technical knowledge interpret the current situation. Does it seem to you that ASI, at least when measured as extent, is unusually sensitive to decline this year? If so, is increase sensitivity due continued loss of multi-year ice? How significant is "rotten ice" for melt trend? Or is it far too early to draw any conclusions? Is the recent ASI extent decline due to something beside temperature, such as inflow of warm water or ice pack condensing wind patterns?


wayne

One conclusion is very simple gkoehler

The over all sea ice mass is lesser than estimated. It is very difficult to rely solely on remote sensing and expecting accurate results. A greater effort in proof checking the satellite data is scarcely done.

wayne

It was a great day in science nevertheless, but imaging a black hole of M87 galaxy has nothing as exciting than filming similar effects on Polar Earth:

https://eh2r.blogspot.com/2019/04/arctic-sunset-like-none-other-prettier.html

Keep in mind that very similar refraction optics captured in the Canadian High Arctic offer the tantalizing prospect that black holes event horizons may actually have some colors.

Elisee Reclus

Dear Wayne

Perhaps you could clarify for me your analogy of "black hole optics" with sunset refraction phenomena in the Arctic. These processes occur under totally different circumstances and as a result of completely different causes. I just don't see how they could be related, even by analogy.

The distorted appearance of the setting sun results from refraction in the atmosphere, light bent by transmission through a distorting but transparent medium which is nowhere near the sun or the observer, but in between. The extreme visual effects are caused by the rays (light paths) passing through distinct zones of different density in the atmosphere, superimposed on one another due to the geometry of sun-horizon-atmosphere-observer. They are most extreme near the horizon because the geometry of the situation is exaggerated--the light goes through more and thicker layers (from the POV of the observer).

A black hole's "appearance" is due to the fact that it is invisible, light can't escape it and it appears as simply an absence of light, a black hole. Light from the surroundings or from background objects or its surroundings is distorted by the curvature of space-time itself, and is totally symmetrical viewed from all directions.

What we see in the astronomical image is not the black hole itself, but the glowing gasses and other debris, the accretion disc, spiraling into the hole--a flat disc of material heated by friction. This material is well outside the event horizon so the light escapes easily, without any distorting effects. No doubt it radiates in all colors, although I understand most of the energy of the emitted photons is in the X-ray region of the spectrum. This final, most energetic emission occurs just outside the event horizon and at the distances involved appears to us as a point source, not an extended object. If it is distorted by the gravitational lensing, the distortion is symmetrical and would appear the same in any direction (a ring of X-rays surrounding the hole).

Other than the fact that there is some geometrical distortion of the light in both the Arctic and the astronomy cases, they have nothing in common. Two entirely different physical processes are at work here, and the visual appearance is entirely different.

AnotherJourneybyTrain

There didn't seem to be total symmetry to the black-hole image....

Neven

This might offer an explanation.

Elisee Reclus

Dear AJBT

There are a number of possible reasons for the unsymmetrical nature of the image of the accretion disc.

The visible light signature of the disc may not be close enough to the event horizon to be gravitationally lensed, so we are seeing its true, distorted shape.

The disc is chaotic, turbulent, and filled with knots, clumps, eddies and other irregularities.

The disc may be partially obscured by dark nebulosities in the line of sight.

The disc plane may be tilted with respect to the line of sight, i.e., it is not orthogonal to it.

The odd shape may be an artifact of the imaging technique, my understanding is that it was acquired using Very Long Baseline Interferometry, a calculation-intensive process.

It would be very useful if someone would include a space bar into the image so we could get some rough idea of the scale of this object. i.e., how many parsecs across is the disc, the hole in the middle, etc?

It would be also useful to know the image resolution, both pixel size (in parsecs)and the color resolution. i.e., how many colors, in the spectrum are represented? Is the red and yellow true color, or false color (arbitrary color assignment to different sensors)or pseudo color (color value assigned to pixel brightness level)?

wayne

Hi Elise

Hawkins described the event horizon light has been compressed in thin layers, same here. The light which escaped in the brighter "doughnut "
has escaped extermination through a very long journey , The light seen in my pictures are from a long distance, not as long as trillions of miles, but hundreds of kilometers if not a little more. Similar in nature. There is no symmetry as another journey said....

wayne

Is light effects caused by gravity induced thin atmospheric layers..... A similar physics outside the B.O. horizon event. Here on Earth, mainly unknown.

gkoehler

Getting back to Arctic sea ice - which is the better predictor for when there will be an "essentially" ice-free September? (defined as less than 1 million km2 extent).

I can't reconcile the NSIDC September minimum extent trend
http://nsidc.org/arcticseaicenews/2018/10/
"The linear rate of sea ice decline for September is 82,300 square kilometers per year, or 12.8 percent per decade relative to the 1981 to 2010 average."

--- with the PIOMAS ASI linear volume trend as graphed by Wipneus:
https://sites.google.com/site/arctischepinguin/home/piomas

Using NSIDC trend, it would take another 50 years, ca. 2070 before September minimum reaches 1M km2. But PIOMAS volume trend reaches near ZERO ca. 2031. Volume is not Extent, so thinner ice will yield a higher ratio of Extent-to-Volume as decline continues, but Zero ice volume = Zero ice extent. Thus, according to PIOMAS trend, the 1M km2 extent threshold would arrive ca. 2030.
So which is it, 2070 (NSIDC) or 2030 (PIOMASS/Wipneus)?

My guess is that with continued loss of multi-year thick ice, a functional change has occurred which will lead to accelerating decline of Extent over the next decade. Thus, I think 2030 is the more reliable prediction.

And repeating previous post - lots of info on Arctic temperature, but what is relative influence of warmer ocean water influx vs. air temperature and cloud cover on Arctic sea ice melt, and is there is a web source tracking temperature and amount of ocean water influx?

All responses welcomed, even guessers like me.

D_C_S

Elisee Reclus,

The image was made from radio waves, so any colors are artificial.

This link shows the scale of the image compared to the solar system:

https://www.explainxkcd.com/wiki/index.php/2135:_M87_Black_Hole_Size_Comparison

Robert S

gkoehler. I think that the issue is that the stochastic elements outweigh any ability to predict "ice free" status based on a curve. I expect that within 5 - 10 years we will be in a place where any single year in which all the right (wrong) factors come together could be "ice free".

Elisee Reclus

Robert S & gkoehler

The observed SIE satellite data is uniform and unambiguous, derived one way from basically one sensor. Its noisy, but the linear regression is really compelling. Its usually enough to stop a denialist in his tracks, unless he's on somebody's payroll.

However, we only have 40 years' worth of data, so it doesn't make much sense to do much more than a linear least-square's fit through it. Subjectively, it looks like a slight decrease in slope around the turn of the century, so maybe a more complex curve, a parabola perhaps, might be a better fit.

But that is subjective. Still, the linear regression is scary enough. Roughly half the September SIE is still there after 40 years, even if there is no second derivative the rest will be gone by by 2060. And although I can't prove it, my guess is the curve will get even steeper between now and mid-century.

Not in my lifetime, but certainly in that of our children. Now how THAT will translate to changes in global weather patterns, particularly rainfall, is something else again.

The stochastic elements do tend to cancel out in the long run.

AnotherJourneybyTrain

Lol @ D_C_S, so the black hole was bigger than the orbit of Pluto?

AnotherJourneybyTrain

...I'm not sure I can believe that....

AnotherJourneybyTrain

gkoehler, essentially it never will get below 1, 000, 000 sq km because the Beaufort Gyre will always save a fair slice of, ...um, the (sea) ice. I see the 1, 000, 000 sq km mark as an marker of no less than true Armageddon but certainly not necessarily possible and/or probable.

Elisee Reclus

According to WIKIPEDIA

The radius (in kilometers) of a black hole is approximately 2.95 times the mass (in Solar Masses).

So a 7 billion solar mass black hole would have a radius of 2.065 x 10**10 km. That's 138 AU.
Pluto's mean distance from the Sun is about 39 AU.

This is an extraordinary object. The black hole in the center of the Milky May is thought to be only several million Solar masses.

AnotherJourneybyTrain

Lol, I stand corrected.... that's some serious dimensionality going on there!!

Elisee Reclus

Serious dimensionality indeed!

Long before a black hole was proposed as the mechanism driving this active galaxy, astronomers were aware that something really profound was occurring there. Jets of ionized plasma tens of thousands of light-years long were being ejected from M87's nucleus at relativistic speeds.

One researcher speculated if maybe what we were witnessing was really a colossal industrial accident. So yes, there is, (at least), a metaphorical analogy to how our own planetary engineering has perturbed our own planetary environment through climate change.

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