Support the Arctic Sea Ice Forum and Blog

Show Posts

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


Messages - Dharma Rupa

Pages: 1 ... 8 9 [10]
451
Arctic sea ice / Re: The 2017 melting season
« on: October 09, 2017, 07:05:06 PM »
The graphic below shows the palette, its desaturation, and a static image of near-terminal blurs taken from the one-click interactive 3D surface plot in ImageJ. (Forum software does not allow the interactive display.) Some hills and valleys are consistently present that aren't so evident in flat images.

I'm going to have the problem of not knowing the vocabulary very well, but I think the hills and valleys are basically represented by the grey scale (saturation?).  What would happen if you were to keep the hills and valleys as a monochromatic and replace the "normalized" color signal with a different measure -- for example ENSO?  That is a reduction of the relative warmness to the status of background fabric and presentation of the other signal overlayed.  (Of course, ENSO might turn out to be a meaningless choice, with some other signal showing a significant and possibly unusual correlation.)


452
Arctic sea ice / Re: The 2017 melting season
« on: October 09, 2017, 04:00:13 PM »
Quote
can you smear that first graph even more?...a lot of smoothing, please.
First the rankings graphic has to be cleared of its dithering, internal and external borders, and text. Then the outer cells need to be expanded a cell's width to reduce edge effects. Then a (gaussian) blur radius must be selected, here a 0.5, 1.0, 1.5 multiples of cell dimensions. Then the blur can be iterated until effective stabilization. Because the forum does not support png animations, just some snapshots of the process are shown below. (A gif animation is restricted to 256 colors per frame and the blurring creates far more, necessitating reduction, which results in forced contouring.)

Thank you!  Aside from the obvious warming, there seems to be the beginnings of a trend to comparatively cool summers in the last few years.   Too early to call it a demonstrated pattern.

453
Arctic sea ice / Re: The 2017 melting season
« on: October 09, 2017, 01:39:40 AM »

A-Team, can you smear that first graph even more?...a lot of smoothing, please.

Quote
"What are those stupid numbers? Celsius? Fahrenheit? WTF?"

454
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: October 07, 2017, 08:11:42 PM »
The clouds in the winter block heat from radiating into space.
That brings up some interesting questions about the relative importance of the different greenhouse effects of H2O, re-radiation, and enthalpy; which I think I shall bring up in the Stupid Questions thread.

OK....What is the major current effective contribution of H2O to Arctic warming during Polar Night?

Is it the cloudy effect reducing total longwave radiation?  Or is it the water vapor restraining cooling because there is a lot of open water?

Actually.....Is it more cloudy in Winter than it used to be?   I know it is more humid.

455
Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 07, 2017, 08:05:55 PM »
The clouds in the winter block heat from radiating into space.
That brings up some interesting questions about the relative importance of the different greenhouse effects of H2O, re-radiation and enthalopy; which I think I shall bring up in the Stupid Questions thread.

456
Arctic sea ice / Re: The 2017/2018 freezing season
« on: October 07, 2017, 03:05:42 PM »
Temperatures at night tend to fall to the dew point.  The major factor determining the dew point is the presence or absence of nearby open water.  The largest recent change in the Arctic climate has been the significant increase in open water.

Temperatures during the day tend to rise as sunlight hits the surface.  The major factor preventing sunlight from reaching the surface is clouds.  Clouds tend to increase in the presence of open water.  The largest recent change in the Arctic climate has been the significant increase in open water.

457
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: September 25, 2017, 12:33:20 AM »
Hullo Dharma Rupa - wind shear. Verical wind shear is not actual movement of air vertically but the difference in wind speed and or direction at different heights in the atmosphere. Suggest you go to Wikipedia for explanations well above my pay grade.

OK, but it is still vertical movement of the air over large regions with which I am interested,  Is there anything that displays that fairly well?  I know that lows tend to fill in and highs tend to empty, but with all the things going on at different levels in the atmosphere looking at cyclones and anti-cyclones doesn't really tell me where the air is coming from and going to.  That only tells me where the air is spinning at.

458
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: September 24, 2017, 05:06:43 PM »
I hear about vertical wind shear with respect to hurricanes, and it seems to me that the vertical motion of air is rather important to our understanding of what is going on in the Arctic.  I was wondering if there was anything similar to what nullschool does with displaying wind, but up and down rather than east and west.  This is generally the Hadley Cell and friends, but I'm interested in near real-time, not theory.

459
Arctic sea ice / Re: The 2017/2018 freezing season
« on: September 24, 2017, 02:46:11 PM »
If we had a blue ocean summer I'm sure the DMI graph would stray far away from norm too, in summer, once the ice is gone.

I'm sure of that, but that will be in the future, not the present (and recent past).

Actually, the big change in DMI 80N happened in a single day in December 2015.  The question this winter is, will it continue for a third winter or revert to the norm -- and so far it's looking like it will continue.

460
Arctic sea ice / Re: The 2017/2018 freezing season
« on: September 23, 2017, 06:01:36 PM »
I know people have considerable reservations on the usefulness of the DMI 80+ N temperature graph. For observers such as me, at least it gives an idea of the direction of travel. At the moment, it suggests slow refreezing in the high Arctic.

I'm perfectly fine with DMI 80N as a gross measure of what is going on.  I can understand why people might not like it when looking at the details, but it tells us rather directly that the big change in what is going on is happening in the Fall and Winter, not the Summer.

461
Arctic sea ice / Re: The 2017/2018 freezing season
« on: September 23, 2017, 05:27:13 PM »
Last year I thought this was an interesting diversion, but this year it is beginning to look like a trend:

462
Arctic sea ice / Re: The 2017/2018 freezing season
« on: September 19, 2017, 05:21:05 PM »
That would be true only for those locations consistently below freezing.  Otherwise, we would expect more of the snow to fall as rain.
I think you can use the northward march of the permafrost and several species of trees as a pretty good proxy for the rain/snow line.  Still far enough south that I think we can expect plenty of snow this winter, but maybe not a decade from now.


463
Arctic sea ice / Re: The 2017 melting season
« on: September 19, 2017, 05:15:19 PM »
...
A fascinating year so far, and one which may possibly reflect a new transitional pattern where feedbacks from increased water vapor like cloud cover and increased snowfall attenuate summer extent loss.

I think this will continue for some time, possibly even decades.  ...

We are very fortunate I think, that recent melt seasons have been anemic.
Not so simple. Summer extent loss being reduced by extra clouds and snow is a thing, yes; but also, winter/spring thickness loss is also a thing because of those same things, - extra clouds (preventing radiative heat loss from the surface to space basically) and extra snow (better insulation preventing normal thickness to form). One can quite count the latter effects as "preemptive loss of summer thickness and thus, also extent". Fortunate we are, yes.
I tend to go with this analysis, and with the general WACC prognosis and maritime climate.  I think we have "warm" wet winters and "cold" wet summers until the point is reached where there is no longer enough ice to maintain a fresh-water cap, at which point the thermocline breaks down and the ocean melts out.

464
Arctic sea ice / Re: The 2017 melting season
« on: September 13, 2017, 01:42:52 AM »
i can't comment on your assumptions about the ice having little impact/importance to the rest of the global climate...

I don't think you understood where Nick was coming from.  Arctic Ice has about as much importance in climate change as a canary has to coal mining operations.

465
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 11, 2017, 09:22:46 PM »
In September Greenland ice normally increases (extent and area) due to increased Fram Strait export. Not this September until now, heading for a record low at a record late date.

Is there anything to export?

466
Arctic sea ice / Re: IJIS
« on: August 27, 2017, 07:14:35 PM »


SH: What IS the probability of being "gobsmacked"? :-)

There is 100% probability of me being gobsmacked if 2017 ends up in 1st place.  :o

I foresee a possible scenario that might bring on a gobsmack. Namely, a minimum after the  September equinox or possibly a new precedent for an October minimum. Smaller than average August extent losses are taking place in a context of low volumn and of cooler temperatures. The low volumn will continue. As it is already as cool as it has been in September in recent years, the only requirement here would be a continuation of the temperature level that is being experienced now, rather than a more normal decline. Put differently, because it is already cool above 80°N, it may simply continue to be the same in coming weeks as it is now. That could happen.

Like 2012:

467
SIPN just recycles the predictions from earlier months, unless its updated (e.g. Rob Dekker's contribution is specific to June, but SIPN counts him as having made the same prediction in July and August too.) This exaggerates how stable the SIPN predictions are from month to month, since quite a few of the August ones are really June or July predictions.
That seems like a bad idea, unless the person making the prediction explicitly chooses to retain the same prediction in later months.
It does seem to me they are conflating two kinds of prediction then -- though I don't know if that is bad or good.  My gut says I'd like to know both the static early prediction and the running late prediction; which would mean that simply tossing the two together would not be to my tastes.

468
Arctic sea ice / Re: IJIS
« on: August 25, 2017, 10:19:39 PM »
If you mean the blue line that reaches its minimum just above 4.0 in late September, yes, that's 2007.

It is hard to know how to talk about these ranks/places.  "Higher/lower" ranks, and "better/worse" places are ambiguous.  6 is a "higher" number than 5, but because we typically consider ranks close to 1 to be "good" (e.g., in races) we often think of 1 as the "highest" rank.  I struggle with this in every post here.

So I'm guessing that by "no worse than fourth" you mean that SIE will end up in 4th, 5th, or 6th place... meaning that 3rd, 2nd, or 1st would be "worse".  Which makes sense, from the ice's perspective....

Yes, from the ice's perspective....more is better.
For someone from Enceladus' perspective there is no better or worse here, so perhaps you could find a less value laden vocabulary....for example, 3rd least ice.  (And the ice couldn't give a damn.)

469
Arctic sea ice / Re: The 2017 freezing season
« on: August 25, 2017, 10:06:21 PM »
Given that frazil ice can start to form when air temps are down to -6 C, we are not far off that figure according to nullschool at 85N 77W.

Alert, at the north coast and of Ellesmere, is now experiencing below 0° temps on a daily basis, but not yet down to -6°
Since the Arctic summer has been 'cool', I wonder whether the autumn will revert to mean by being relatively warmer?
I think you want to watch this for an answer:

470
Arctic sea ice / Re: The 2017 freezing season
« on: August 24, 2017, 08:06:15 PM »
Not ready for fall yet...
 :)
Fall is the second best season!   I've have enough of the heat and humidity.

471
Arctic sea ice / Re: What the Buoys are telling
« on: August 23, 2017, 07:59:16 PM »
thanks, didn't know that,

to extend the question a bit, of course without questioning your reply as such, the ice-shelf that broke of in the antarctic is what then, a floe ?

i know its OT but i hope one more question is allowed since it originated on-topic and is just a side-question to further make use of the correct terms and since we're already at it, if an ice-floe ( thick one of course ) would brake loose and later would be sighted somewhere south of greenland from the bridge of a vessel, would there really be made a difference and that one floe would be called floe while all the bergs around it would be bergs ?

i hope it's not too much asked but i really wanna know once and for all :-)

I think the original objective was to distinguish the very hard very old ice from a glacier from the softer newer sea ice.  An ice shelf is more like a glacier in this regard.

A berg is much less likely to give way to even a steel boat than sea ice of the same size.


472
Arctic sea ice / Re: Northwest Passage thread
« on: August 20, 2017, 08:41:32 PM »
To me it's open when all the ice is gone on sea ice concentration maps, such as Uni Bremen's.

I wouldn't call this entirely open, let alone the central route (which to me signifies a truly open NWP), but it will be soon.

Any chance we can find a more nuanced vocabulary?   How about "passable" and "open" as a first try?  The NWP is passable if an icebreaker can get through it, and open if some idiot can sail it without being killed by an overturning berg.

473
Arctic sea ice / Re: The 2017 melting season
« on: August 16, 2017, 07:01:07 PM »
What's the mechanism for extent loss all the way into October? It'll have been below freezing over most the Arctic for a whole month by then.

Some spots will continue to melt, sure, but higher latitudes will be freezing up.

Yep, in fact, one could argue that the high CAB freezing season typically starts at the end of August (depending on weather).

Question. What impact might so much open water appearing across the high CAB have in delaying this? Decreased albedo, ocean warming in those polynyas. How much does concentration have to drop before the coupling between the ice and 2m air temperatures starts to break down?
2016 was the first year that had widespread melting in the "high CAB", more noticeable in area stats than in extent numbers. On Sep 10th and Sep 11th the whole center refroze, while extent continued dropping for a few more days thanks to the periphery.
In order to delay refreezing I believe the whole area has to be clear of ice for at least a few days (weeks?) to allow mixing of the cold fresh water layer.
This year looks quite similar to 2016 around the pole. I therefore expect this year to have an early refreeze as well, before Sep 15th, unless some major compaction event magically brings all the ice to the center and clears the periphery.

That would be after the Dec 2015 switch to a maritime climate.

I'd not be suprised by an early refreeze near the pole.  It is not at all clear to me that really means anything.  I will be looking at areal temperature over Winter....   Ooops Off topic.

I want to know what this season looks like....after the end.


474
Arctic sea ice / Re: The 2017 melting season
« on: August 16, 2017, 12:26:50 AM »

Neven wrote in his post that we dodged a cannonball this year, which I agree. But this luck can't go on forever, sooner or later we'll get a brutally bad melting season.

I would argue the arctic got hit by Curlin's Proverbial "cannonball" this past winter. So if we had below average winter temperatures, with above average summer temperatures, would we have dodged the "cannonball"? I hypothesize the warm winter temperatures and their corresponding cooler summers over the last decade are a result of the same mechanisms. Weather patterns do not get stuck months let alone a year at a time. Classifying this as "luck" is nothing more than wishful thinking.

I'd tend to agree with this, with the mechanism being water vapor.  Remember that this Summer has only been a couple of degrees cooler than what we would call a Hot Arctic summer, and the poles are warming 10 times as fast as everything else.

Won't take much to have both a foggy Winter and a foggy Summer.  At that point I think we will have achieved WACC.

(I'm still not convinced this melting season ends in September -- at least for bottom melt.)

475
Arctic sea ice / Re: IJIS
« on: August 14, 2017, 04:10:23 PM »
what i want to say is that 0% chance for 1st i wouldn't sign, (a) for the above reasons and (b) because i generally try to never say 0% and to never say 100% sure if it's avoidable.

I have to agree with this point in particular, but I'd also like to point out that the unknown unknown is the probability that the melting season never (in this Age) ends.

There are two basic theories on how the ice will finally melt out, and I am in the "it won't matter what time of year it is" camp.

476
Arctic sea ice / Re: Latest PIOMAS update (August)
« on: August 04, 2017, 03:20:24 PM »
It is quite remarkable how the volume trajectory keep tracking 2014, that year also had a remarkably warm winter, heavy snow cover and lots of ice in the Barents. Could this be an indication on melting patterns in case of warm winters and heavy spring snow cover, or is it merely coincidental?

I'm expecting another warm Winter -- WACC.  Probably be more interesting, and harder to understand, if we didn't have one.

477
Arctic sea ice / Re: The 2017 melting season
« on: August 03, 2017, 08:47:10 PM »
My bet is that all the open water there already will tend to suck the weather systems in and keep driving the loss, rather than 2017 taking a 2011 path and heading for minor loss and a #4/5 level finish.

I'm fairly sure that all that open water will pull in the fog next Winter.  I don't know enough about cold-core storms to really say about the rest of Summer.  I will note that we've had plenty of them the last couple of years.

478
Arctic sea ice / Re: The 2017 melting season
« on: August 02, 2017, 12:15:56 AM »
This one doesn't flatter the sea ice at all.


The ice is in the worst shape that it has ever been in human history.

Some of us think so....but the metrics make that a hard call.

479
Arctic sea ice / Re: Year-round ice-free Arctic
« on: August 01, 2017, 11:32:38 PM »
Sometimes I doubt this is sane or helping anything. Sometimes It seems to me like a morbid fascination. But here I go. And go on watching ...
Me too!

I do think that from a HuMan perspective the changes in both computer science and bioengineering are more important, but from a biosphere perspective the North Pole is the center of the Universe.

480
Arctic sea ice / Re: 2017 sea ice area and extent data
« on: August 01, 2017, 11:22:57 PM »
There's coastal ice "appearing" all over the place today. Did a mask change, or something?

Tomorrow will have a new monthly mask applied, so expect a first-of-the-month drop.

I think the (false) coastal ice in the Bering, Okhotsk and Baltic regions is to disappear, as well as a few minor shavings. Altogether the FOTM drop will be perhaps about 35k extent.

Um...I've been watching you long enough that I want a translation.

I kinda get how you know the satellite's failings, but I just see the woof and wain without enough understanding of what is real and what is a ghost.

481
Arctic sea ice / Re: The 2017 melting season
« on: August 01, 2017, 11:09:30 PM »
...
Maritime climate.  The Arctic is no longer a desert.
Partially true; oversimplified. The change is gradual. It's still a desert say April, for example. But direction of change is indeed towards maritime climate year-around. We know Arctic ocean had crocodyles inhabiting it in the past. Still we're far from that, for now. Late summer and autumn are much maritime already, yes; even now, Arctic looks much like a part of Pacific system at 850 hPa, for example. Switch to 250 hPa, though, and it's not (yet). Remains of Jet Stream in action...

That was my entire objective...a bumper sticker.

Last Winter was warm enough I might need to be convinced about April.

482
Arctic sea ice / Re: The 2017 melting season
« on: August 01, 2017, 06:09:31 PM »
I've noticed that each of those years had warmer the DMI north of 80 temperatures in summer than 2017. This year it still below average for the entire melting season but was above average for the whole freezing season.
...

However, comparing it with 2012...
...

This makes perfect sense to me. Aren't temps uniformly close to but very slightly above 0C just what one would expect give the combination of rapid melt, high insolation, and robust atmospheric  transport/mixing across the 80th parallel?

I don't think it's too simplistic to draw the analogy with defrosting a freezer by directing the airstream from a fan at it. The basement gets cold for a while, but the ice melts 10x as fast as it would otherwise.

Subjectively, there's been a lot of hazy cloud / fog forming quickly over clear areas throughout the season. If spring in Minneapolis is anything to go by, that's what you get above and downwind of a still-frozen but rapidly melting lake on an otherwise hot day.

Maritime climate.  The Arctic is no longer a desert.

483
Arctic sea ice / Re: The 2017 melting season
« on: August 01, 2017, 05:54:34 PM »
The long-term trend will of course be sublinear because you can't get negative extent, and it gets harder and harder to melt the remaining ice. But in the satellite era it appears pretty close to linear.

I keep seeing it said that "it gets harder and harder to melt the remaining ice," or words with that meaning, but I cannot remember ever seeing an explanation why that might be so.  Seems to me that just like in a margarita, the last of the ice would go quickest.  By then you have run out of cold.

484
Arctic sea ice / Re: Gulf Stream stall
« on: August 01, 2017, 02:44:50 PM »
All a nice theory, but the evidence so far is that the Western Boundary Currents (e.g. Gulf Stream) have shifted poleward over the years.  Just ask the lobster fishermen and the fishermen on the Grand Banks.

485
Arctic sea ice / Re: Latest PIOMAS update (mid July update)
« on: July 31, 2017, 06:50:43 PM »
An observer such as I has not the expertise to research why the sensors and algorithms from the various satellites and scientific institutes come up with such different results on volume. Maybe some genius somewhere will crack the technical problems. I hope so. Until then I guess one sticks to one set of results. Consistency and multi-year trends matter most?

One set of results in the threat devoted to that set -- and yes, consistency and trends.  Separate topics for comparing sets of results -- for estimating skill.

486
Arctic sea ice / Re: Volume vs extent, by the numbers
« on: July 28, 2017, 05:37:55 PM »
Why do I believe that year round ice free is a long way off?

Hudson Bay is ice free annually but freezes over each winter despite being at a much lower latitude than the CAB. The Bering Sea is even a better example. Despite being very stormy and subjected to warm Pacific Ocean waters, portions of it continue to freeze each winter. The CAB will behave in a similar fashion for decades, IMHO.

You might be right, but I think Hudson Bay will freeze over in winter long after the CAB remains ice free all winter.  The Bering is more like the Hudson than the CAB.

Basically, I think deep sea swells and overturning will take over for the bulk of the Arctic well before the coastal waters can ignore the cold continents.

This is why I see the possibility of a volume near 0% with extents near 100% -- maybe, for a year or two -- although I see it just as likely that the volume and extent both crash to near 0 year round in the same year.


487
Arctic sea ice / Re: Volume vs extent, by the numbers
« on: July 28, 2017, 04:54:15 PM »
Count me as one who believes that year round ice free is a long way off and, after our first BOE, we could have succeeding years where substantial amounts of ice survive the melt season, dependent on weather.

All the short-term evidence agrees with you.  All the paleontological evidence is more ambiguous, but tends to disagree with you.

We live in interesting times.

488
Arctic sea ice / Re: Volume vs extent, by the numbers
« on: July 26, 2017, 11:16:11 PM »
I've seen enough thin skins of ice to think it believable to have a volume close to 0 and almost 100% of the Arctic covered with ice, though I'd be more inclined to expect that in November than September.

When talking about convergence of volume and extent I think you need to question whether our measurement skills are up to the task.

489
Arctic sea ice / Re: IJIS
« on: July 26, 2017, 02:17:19 PM »
Insisting the old measures are perfect would be wrong, but suggesting that the old measures have better skill (could be more wrong in one particular year but generally taken over several years a little better skill) seems quite easily defensible to me.

The problem is that the old measures are going to go from having fair skill to having no skill at all.

490
But we want to be able to point to some specific date and say "OK, on this day, the Arctic Ocean was ice free" with perhaps a "(for all practical purposes)" footnote if we're Walt Meier.  It doesn't matter to the climate, but for this kind of "social" purpose everyone seems to have settled on 1.0 million, and I'm OK with that. 

Ice free (in all its forms) is something we care about and they do not.  When cargo crosses the Arctic and doesn't have to deal with either the NW Passage or the Northern Sea Route then the general public -- and the people with money -- will notice.  (I'd say when they didn't have to deal with national borders, but I think the Bering Strait messes that up.)

BTW -- what was the question?

491
Arctic sea ice / Re: The 2017 melting season
« on: July 25, 2017, 11:43:41 PM »
When it comes to the 2017 melting season my main question is if we are going to have a repeat of the 1016 freezing season.  That is, does this melting season really end in September?

492
Arctic sea ice / Re: IJIS
« on: July 23, 2017, 07:58:16 PM »
...
My current working hypothesis about this can be summarized thus:  once melt retreats past about 75N over all, the system dynanimics change sharply. My thought is, that open water becomes a buffer which more efficiently and evenly redistributes heat.  I think the dynamics of phase change come into play as well, with heat which previously melted ice, taken up by evaporation, which in turn further contributes to increased albedo.  To summarize, we see increasing feedbacks from different mechanisms that don't exist or are retarded at higher levels of ice coverage.  I think they are the only reason we aren't seeing open water at 90N by early August.
Not sure about the rest of your analysis, but I agree that the open water more evenly distributes heat.  The problem is, if this is correct then the ice will more suddenly go from covering large areas to completely disappearing.  Thus, everything points to an Arctic which very suddenly changes -- even if we cannot tell when this will happen.

493
Arctic sea ice / Re: The 2017 melting season
« on: July 22, 2017, 11:54:34 PM »
Less ice volume means less ice to melt means a smaller freshwater lens means a weaker halocline means a warmer ocean.  Just how dark does it have to get before the water vapor condenses out and the atmosphere begins to act like a desert again?

I think the next freezing (?) season will be more interesting than this melting season.


Pages: 1 ... 8 9 [10]