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Messages - Bruce

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Arctic sea ice / Re: The 2015 melting season
« on: July 24, 2015, 11:50:02 PM »

there may be a solution found here:
Forgive me if I'm late to the party and this has been suggested, but GMT (The Generic Mapping Tools) work with NetCDF files and would let you convert grids to ASCII (as well as doing all sorts of other things). Pretty much every package manager I've encountered has pre-built GMT distributions so installation is trivial. And it's free. "Free" as in not-even-asking-you-to-donate free.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 02, 2014, 05:45:57 PM »
It is high time for an update of the Fram Strait animation. As you can see there is little or no export, neither the Fram or the Victoria Channel.
Seems like a fair bit through the Victoria. It backs up and changes direction at some point, but the beginning and end of the animation show pretty strong flow.

The Fram, on the other hand, seems like it has been pretty dead for most of the summer. Probably plays some part in this year's relatively high extent.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 30, 2014, 07:15:26 PM »
The model informs the shape of the curve that you use.  F = m1*m2/d^2 is a model.  You still want to go out and measure m1, m2, and d for a particular application of the model.

That formula is the direct result of a theory. It is not a model. A moel would be to approximate the force and make it constant when distance is very small, to avoid too large errors near the d=0 singularity. That is THE model that can be used in computer simulations. The actual formula cannot be used for many calculations due to its singularity.
It's an approximation of reality. The problem with it isn't that it's singular at d=0, it's that it assumes the objects' mass is all concentrated in points at their centers. Which is fine if d is large relative to the objects radii, but not otherwise.

This is a good example of one way models can go astray. If you were modeling the mutual orbit of a pair of objects using the above equation (with a "G" added), you could do quite well for many situations (like, say, the Earth-Sun system), but would depart increasingly from the data as the objects got closer together (for example, the Earth-Moon system, where tidal forces play a significant role).*

The GCMs, which are far, far more complex than this simple orbital model, have many more ways to go wrong. It's an incredible testament to science and scientists that they do as well as they do.

*Yes, to get the orbits really right you'd need to include the other planets. This is just an example.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 30, 2014, 06:38:58 PM »
Don't worry folks, Arctic won't melt before 2080, right?
I will probably continue to laugh at this past the lifetime of many of the so-called scientists who argued this till just recently. So much ego, all just to avoid social labels, and retain their cult identity as "moderates". I am sure our grandkids will understand, if they will be among the survivors.

I'm not willing to go remotely this far in condemning scientists. Scientists work and communicate in an environment where language has very specific meaning, and that language does not necessarily translate well to the general public. Think about words like "error," "significance," "confidence," etc. These words mean totally different things to the public, and scientists are only slowly learning to better communicate their findings under the microscope of intense public scrutiny and massive politically-motivated criticism. In addition, scientists are by training conservative in their assertions. They typically go through in internal and external peer review process with every publication and are careful to assert only what they can back up with their research. Again, the public, accustomed to politicians and pundits who constantly shoot for the hip and are never held accountable for anything they say, don't really understand that.

If scientists are guilty of anything, it's not adapting to the public scrutiny sooner and better. And even that is forgivable since most of them didn't want it in the first place.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 29, 2014, 09:48:20 PM »
I'm sorry but saying the models "only work as long as the future looks like the past" is a total misconception. The models are physical models based on physics worked out theoretically and underpinned, in some cases 'tuned by', obervational work. They do not depend on the past as a guide, they use physics. [...]
This is a dramatic overstatement of the truth. The models have numerous parameters, most of which are only approximately known. Look at the error bars on total climate sensitivity -- they're enormous. The models are tuned over many runs to make them consistent with both science and history.

I'm not suggesting that the models are junk or that they should be thrown out with the bathwater. The GCMs are quite good, and have accurately predicted a number of important features of climate change. But the idea that they are boxes of pure applied physics is not remotely true. Like all models, they are approximations of reality. And where approximations are made, uncertainty creeps in. No new physics or magic is required. Simply not properly accounting for changes in parameters or relationships is enough to send one's model wildly astray. In a rapidly changing system, it is very difficult to remain on track as you model into the future. Much harder, in point of fact, than fitting a curve to some data.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 28, 2014, 06:38:05 PM »
F=ma is not something that can be checked by experiment. It is a definition.
You couldn't possibly be more wrong. At the risk of taking this thread further off topic, F = ma is a purely empirical relationship. Which is to say that it can only be supported or rejected by experiment and observation. And to explicitly make my earlier point, which seems to have been missed, there is nothing that says that it is either unique or that there isn't a better fit to the data that has yet to be discovered. Thus it is "magic" by the earlier definition, but "science" by every other.

Getting closer to on-topic, Chris, I know we disagree on this topic, and I respect your opinion (and even admit that you may end up being right). But the models suffer from the same problem that simple curve fitting does: they only work as long as the future looks like the past. The models, of course, notoriously missed the rapid melt of the last decade.

With such a complex system, there are a large number of competing factors, and each has its advocates as to its dominance. The "right" hypothesis may be out there (possibly yours!), but the space is crowded. My belief is that there is more than enough heat to melt all of the ice already, and it is just a matter of time until the "perfect storm" (possibly a real storm) delivers it. With the added heat of each passing year, the "storm" needs to be a little less perfect. When you melt 85% of your starting ice in a season, it doesn't take a lot to kill that last 15%.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 27, 2014, 06:13:02 PM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 27, 2014, 06:08:28 PM »
The whole point of the confidence intervals on the graph is to account for the uncertainty due to the noise. The data point for this year will be far outside the confidence interval for this year. This implies that either the model for the noise is not correct, or the trend line is not correct.
If you establish confidence intervals then, by definition, some points will fall outside of them.

I've said this before, but I'll say it more strongly. You can choose any predicted value at all for the ice volume for 2014, and I can give you a curve which exactly goes through every point on the graph including your chosen prediction for 2014.
This is a straw man. You can use (for example) the Lagrange interpolation formula to exactly "fit" a polynomial to any sequence of numbers whatsoever, but you'd be hard pressed to find a real problem for which all of the extra parameters are statistically justified (vs. a simpler model). Any measure of a model's goodness of fit should also include an analysis of the number of parameters. And any model that requires as many parameters as there are data points can be rejected outright.

One can play all sorts of games with curve fitting, but I don't see that as the case here. The exponential appears to fit the data better than a straight line, and is a fairly simple, common model. Again, I'm not in a position to defend it, no do I want to, but I think it makes a valid point about what we're seeing: sea ice losses have accelerated. A model that doesn't make that point misses the point.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 27, 2014, 05:38:00 PM »
Fitting curves to graphs is fun.  But without a plausible physical model to back up the chosen curve, it's just numerology.
No, it's statistics. The model is that more heat is being added to the system and it's causing decreased September sea ice coverage. If curve B fits the data better (statistically) than curve A, and curve B's fit is statistically significant, and curve B's parameters are statistically justified, then B is the better representation of the data than A. If you don't think so, it's up to you to come up with a) something better, or b) explain why you don't think the indicated trend will continue.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 26, 2014, 05:28:30 PM »
As a fit for the data, it's really good. But we want to use it to predict when the sea ice volume will go to zero, and it runs into problems for this purpose. The first thing to notice is that although most points fall inside the confidence interval, the data point for 2013 is above the confidence interval. The fact that the last actual value is off the curve should lead to doubt about the curve's ability to predict the future.
This is akin to claiming that since the weatherman didn't accurately predict today's rain, then all climate science is bunk. Surely you're aware that the data we're dealing with are noisy?

This curve's claim to fame is that the 2010 data predicted the 2011 and 2012 data points, but to me that just points up the danger of arbitrary curve fitting. Just because a particular curve works for some period in the future, that does not mean it will work for other periods.
The curve's "claim to fame" isn't that it accurately predicted one or the other year, it's that it is an overall good fit to the data. And yet you're willing to reject it because it didn't fit the data for some arbitrarily short period? Seems a little like Skeptical Science's "Escalator":

I don't want to be in the position of defending that particular fit, as there is danger in extrapolating any time series -- especially one that is controlled by so many factors and competing feedbacks -- but the point of the graphic is that ice loss has been proceeding at an accelerating pace and if that trend continues an ice-free arctic is an inevitability, and sooner rather than later. Whether it is 2017 or 2019 isn't really the point.

Arctic sea ice / Re: Arctic Image of the Day
« on: August 21, 2014, 05:53:51 PM »
I just like the curls in this fram transport melt
Can someone tell (or show) me what these curls are comprised of? I see this stuff in various places as the final stage of an area becoming open water, but I've never been quite clear on what it is. Is it slushy stuff, or just very small floes, or water-logged ice, or is it foam, or...? Any pictures of it from (near) the surface?

Arctic sea ice / Re: The 2014 Melting Season
« on: August 17, 2014, 06:13:58 PM »
Thanks, Chris, for the great analysis. Given your results, I can understand that the CAB "stall" may be largely due to melt ponds freezing. The ESS is a bit harder to understand. Given the weather of the past two weeks, it would be difficult to put down to any sort of freezing. Given the rapid retreat of the ice edge and the generally bad state of the ice, it's questionable to put down to compaction, too. But I note that the ESS had the greatest rate of loss of any region prior to the last two weeks, so maybe we're just seeing that area loss (which I now recall was mostly in situ melting before Friv's ridge came to town) slowing down due to much of the ESS ice being gone. I've attached the CA plot for the region. It looks to me like the first week of Aug. saw rapid loss, then almost completely stalled when area got to about 30% of its peak. It looks like losses may be picking up again, but it's too early to tell.

Looking at all the regional plots, it's the ESS, CAA, and CAB that are the big differences with other recent years (with a bit of Beaufort). Given their low latitudes, there's still time for loss in the ESS and CAA, so we might still see some drops in area. It will depend on how fast the high latitudes freeze.

Thanks again, Chris. That was a big help.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 16, 2014, 05:45:04 PM »
The stall in CT area is almost getting interesting. While we're seeing solid extent declines by most measures, and decent area declines at least by Wippy's measure, CT is basically stuck. I would put it down to compaction, but we're seeing declines in other area measures. Any thoughts? Is it a resolution effect?

Arctic sea ice / Re: The 2014 Melting Season
« on: August 15, 2014, 06:29:55 AM »
I guess I can google that...  I'm getting: the Fram strait is 450km wide.  And says that ice moves at 2% of the wind speed.  Google says 20 knots is about 10m/s, so the ice would move about 0.1m/s.  4 days is around 400,000 seconds, so the ice moves 40 km.  So 18000km^2 of ice area would blow out through the Fram.  Looks like 18K is small compared to the other area/extent losses being mentioned.
Given the current state of the Greenland Sea, ice moving through the Fram will actually increase extent, not reduce it. At least until and unless it melts away. Which may or may not happen.

Friv, I can't argue with your numbers. But we're running out of daylight, so to speak. Right now it's a race as to whether the ice edge retreats faster than the freeze-up advances. But I agree with you that it's going to take some compaction -- I don't think a melt out like we're having in the Chukchi will be sufficient. But the current drift maps favor compaction, so who knows, maybe we will drop below 5M.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 15, 2014, 02:16:47 AM »
The Chukchi open water area might be able to carve it's way to 80N.
I'm going to put that in the "extremely unlikely" category. There is a lot of solid, thicker ice between the current hole and 80N.

The question I'm asking is "Are the areas that are currently yellow and green on the AMSR2 maps going to melt out before they re-freeze?" Normally I'd say "no problem," but this year the ice has been very reluctant to melt. Barring some major weather event, I think we're unlikely to see more that about 750K of (extent) melt for the rest of the year.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 13, 2014, 03:39:25 AM »
Here's the plot I was talking about making with the JAXA data. It's got the averages of the three previous decades, and then the individual years from this decade.* I think it helps make a point about the trend -- no year in this decade has a minimum that's touched the previous decade's average minimum, let alone exceeded it. We are in a distinct downward trend, regardless of the fact that this year and last (will) have minima greater than 2012 or 2007 or any other year.

*I'm assuming the "decades" run 0 to 9, rather than the more traditional 1 to 10. But the result doesn't really change if you drop 2010 from the plot.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 11, 2014, 01:44:28 AM »
No it's not.

The current 9th and 10th lowest years on Jaxa record are 2004 and 2006 both around 5.7 million. 

2014 is currently at 6,259,129 km2.  With 30 days to go in the melt season roughly.  That would require roughly 18K per day or less in losses.

CT is at 4.55 or so according to the thread on here.  To get out of the top 10.  It would have to drop only -400K or less the rest of the way.  Or about -13K per day.

Piomas is already 10th lowest on record as of July 31st.  There is no chance for it to be anywhere below 8th lowest and it's likely to be 5th lowest
Good points, all. And it supports my earlier observation that this year will be below the 00's average, meaning that all five years of the of the 10's (so far) will be below that average. That's not the signature of a recovery, that's the signature of a continuing trend. Maybe even an accelerating trend.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 10, 2014, 06:44:07 PM »
Some people recently discussed this issue of re-baselining the area/extent data, and I agree with those who felt it sends the wrong message. I actually think the whole idea of finding an average in a system that is clearly trending in one direction or the other to be scientifically dubious. It underfits the data and leads to spurious conclusions about their meaning in a way that is analogous to overfitting. While having a baseline is important, it makes more sense to show the trend with the anomaly superimposed, like is done with PIOMAS.

Another approach that I like the the JAXA extent graph, which shows the averages of the 80's, 90's, and 00's (I wish they'd add some earlier decades based on other estimates/proxies). Looking at the graph makes the trend clear, and puts recent years in context. I think they should drop 2007, since it's included in the 00's average, and add 2010 and 2013. If they did that, an important truth would emerge: every year of the 2010's has been below the 00's average (as can be seen by inspecting the old-style graph). This year probably won't be an exception -- if it is, it won't be by much unless something unprecedented happens -- and puts lie to the idea that any kind of recovery is underway.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 09, 2014, 06:02:32 PM »
I am stepping back, I am taking a long view.  I'm pointing out that the short term phenomena do not appear to be syncing up with the apparent inputs, and the observational tools we have appear to be coming up seriously short in giving us a clear idea of what is happening.
By "short term" are you talking about just the last couple of weeks? I though you were talking about the last five or so years. In the very short term (this year) we've had a summer of fairly mild weather and it's only the last week or so that it's gotten really bad for the ice. And it seems to be having a significant impact (see Friv's Aug. 1 vs 8 AMSR2 plots). So I guess I'm missing your point.

I agree that the tools we have are inadequate to fully understand the the system, but that's the nature of science. If it was easy, it'd be done already. One thing a couple of people have mentioned is export through the Fram and other routes to the Atlantic. I think when the story of this year is written, it will show that the export of ice was fairly low. I'd like to be able to quantify the export since no one seems to have a handle on it. Maybe this fall/winter I'll take a crack at something to measure the flux. It will be hard to calibrate, but it might give some relative numbers from year to year.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 09, 2014, 07:11:29 AM »
Where is the energy going?

Increased water temps, modest air temp, all that insolation... What unseen (by me, anyway) changes in energy transport are saving the ice in the face of more measurably greater total energy in the system?
The problem here is that you're not fully appreciating the scale of the system. Yes, this year there is more total energy in the system than last, and last year there was more than the year before, etc. But it is a very, very big system. The relative changes from year to year are very small. If you look at "now" as the last ten years, and compare that to a decade a hundred years ago, there is considerably more energy in the system now(ish), and the amount of ice is dramatically less than it was. But looking at just a few recent years, you can get any "trend" you want -- up, down, flat -- because the short term variance is large.

If you could accurately measure the total energy in the system then, yes, it would likely increase every year. But expecting surface measurements (or proxies, like ice) to show warming every year, year after year, is simply to misunderstand the system. The vast majority of the warming goes into the ocean. If the ocean takes in just a little bit more heat, the year is relatively "cool". If the oceans release a bit more heat than average, then then year is relatively "hot." But these are the characteristics of a very large, very complicated system. It is only by stepping back and taking the long view that the signal separates from the noise, and the true picture emerges.

So the short answer to your question is that the energy is going into the oceans. The practical answer is: just wait a while, it'll make its presence known. If not this year, then next. If not next, then the year after. But eventually it will show up, and probably with a vengeance.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 08, 2014, 05:51:15 PM »
... it's now becoming apparent that the long-term decline continues to be linear rather than exponential ...
More likely Gompertz.  I thought in 2011 that Gompertz fit was about to take over from exponential as the better approximation of reality.  Now it seems better substantiated on the basis of both empirical evidence and reasoning: see the "Slow Transition" thread and Dosbat post.
I think people are also getting confused about where to put the exponential/gompertz curve and why. Extent (or area) could move in or out of an exponential decline while volume remains linear -- depending on how the ice spreads out. Ice thickness varies a lot over a season, and from season to season.

Edit: I'll also note that this plot requires an additional data source to interpret properly. Since the thickness isn't uniform over the arctic, thickness can increase simply by the reduction of the amount of thin ice. So extent (or area) and volume in combination with the graph tell you something about the state of the ice. (This year seems an anomaly, but I suspect that's a problem with the model -- the rapid melt we're seeing in the Beaufort/Chukchi and ESS belies the idea that the ice is anomalously thick.)

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 07, 2014, 10:03:11 PM »
The delta is not so informative today. As an animation the decaying ice look spectacular. There are some  "poofs" to be seen, eg the ice sheet that get dislodged from Wrangel island.
Wow, that's a spectacular animation. And just a week or so of melt.

You can see why extent hasn't dropped that much while area has. But if we get another week or so of this weather, a very large area is going to go "poof" and extent will drop dramatically.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 06, 2014, 03:38:26 AM »
Actually I am inclined to believe scientists might be biased, toward the AGW acceptance side. Which is not good either.
Not good in the same way it is not good for biologists to accept evolution? Or geophysicists to accept plate tectonics?

AGW is the guiding paradigm of climate science, and it should be. Trying to understand the modern climate without it would be akin to trying to understand why an Oklahoma trailer park got flattened while denying the existence of tornadoes. You're doomed to failure, so you'd be a fool to try.

I have no idea what you mean by AGW not being a "tested theory." It is constantly being tested by scientists, and the theory is consistent with observation, experiment, and our understanding of physics.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 05, 2014, 12:52:01 AM »
The ESS is deteriorating fast.  3/4th of it is water logged now big time.
Yeah, today's MODIS image makes it pretty clear that there's nothing there putting up any resistance. If we get your week of warm weather, there won't be much left.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 03, 2014, 06:44:46 AM »
Forgive my ignorance, but why is this so different from our inability to predict what will happen in say 20, 50, or 100 years?
Others have answered, but a simple way to think about it: put a pot of water on a stove. It would be very hard to predict the specifics of the convection currents within the water even if you knew everything about the initial conditions and the heat input. But you could pretty easily calculate about how long it would take to boil.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 02, 2014, 05:30:37 PM »
To quote Depeche Mode, everything counts in large amounts.

If the local releases of methane are large and sustained (relative terms, I know), then they *must* affect local warming. It's simple physics.

To me a much more important question is how long would it take to circumnavigate 70-90 North.  given that it would always migrate to the southern hemisphere in a year or so.
Not quite. Keep in mind that the northern hemisphere has a higher concentration of methane than does the southern hemisphere. That's because of the greater land area in the north, which produces more methane, and greater OH in the south, which helps break down methane, because of all of the ocean. But as more methane is produced in the north (from melting permafrost, clathrate releases, etc.), then that imbalance can grow. Which, of course, gets amplified in the arctic, like everything seems to. So even "well mixed" the methane can cause regional warming in excess of its globally-averaged number.

And finally, PLEASE, PLEASE, PLEASE can we drop the political stuff? There are much better places for it and it will utterly ruin the environment here if it continues. Thank you in advance.

Arctic sea ice / Re: The 2014 Melting Season
« on: August 01, 2014, 01:50:32 AM »
August NSIDC Extent losses graph attached.

High August loss years: 2004, 2008, 2012.
Low August loss years: 2006, 2010 .... 2014?
It's a little hard to predict these things, and searching for patterns will drive one batty. For instance, the high August melt years of 04 and 08 started with relatively more ice (8.3m and 7.4m) that the slow years that followed each (05 and 06, with 7.3 and 7.4, and 09 and 10, with 7.0 and 6.9). So one could argue that since we're starting with a lot of ice (relatively), we should see a lot of melt. On the other hand, the very high August melt years are often followed by two slow melt Augusts. Except when they're not (07/08, for example). So we could be looking at only -1.5m. And, of course, the weather probably plays as big a role as the state of the ice and, while not exactly random, adds a lot of uncertainty.

Statistically, that plot makes August melt look like a bi-modal distribution with means somewhere around -1.5m and -2.25. But there are far too few data points to support that conclusion. The only thing I think one could say for sure is that the trend is downward, arguing for more melt every year, but with a pretty big variance superimposed.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 30, 2014, 06:26:58 AM »
Jaxa says -110K for today (July 29). It'll be interesting to see if the 100K drops are sustainable.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 29, 2014, 08:18:40 AM »
How slow or fast does everyone think that large relatively healthy looking slab of ice will go in what direction the next 10 days?
I think the ice is pretty vulnerable, but a week or 10 days isn't a lot of time to melt a swath of ice that's that vast. My guess is that we'll see the the coastline clear out quite a bit, and the bulk of the ESS will drop in concentration, but not disappear. If the heat and clear conditions last the rest of the August, well, that's a different story.

The open water in the Laptev, though, could expand considerably. I could see it breaking through to 85N if the wind and heat materialize as predicted. Longer term, I think it will be hard for it to maintain its beachhead in the north without continuing favorable winds -- there's just too much ice that can drift in and close it up.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 29, 2014, 03:02:48 AM »
The whole thing was about (in my eyes unreasonable comments) that this year should see some particular melt due to methane levels.
Okay, so methane levels are rising at a rapid rate, but they won't affect melt this year for some magic reason. Got it.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 28, 2014, 07:53:59 PM »
[...]And concerning the atmosphere there are measurements - show us that it is significantly higher than in the past years. I doubt that too.
You're kidding, right? A simple google search on atmospheric methane concentration will demonstrate that methane has more than doubled in the atmosphere since pre-industrial times and appears to be on a renewed uptick in the last seven years or so (corresponding, interestingly, to the new regime of dramatically lower northern hemisphere snow and ice cover).

Arctic sea ice / Re: The 2014 Melting Season
« on: July 27, 2014, 04:49:37 PM »
Robert Scribbler covers another flux into the arctic OHC which is increasing in magnitude:
Thanks for the link -- that's an interesting article. I suspect he's overestimating the negative feedback effects of the fresh water, but only time and more research will tell. In the meantime, he's one more analyst adding his voice the the importance of the predicted high pressure patterns. It will be interesting to see what happens.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 27, 2014, 04:37:30 AM »
We have to be governed by the actual data, not by the most pessimistic interpretation of the longest-range forecast we can find.
So you think Friv is overreaching by looking at 5 to 10 day forecasts, but you're willing to predict where we'll be in the middle of September based on where we are now?

Arctic sea ice / Re: The 2014 Melting Season
« on: July 25, 2014, 08:19:16 PM »
What the temps really mean in terms of melt is: above 0C, melt, below 0C, no melt, in usual conditions, fresh water. Salty water, take or take one or two degC
Yes, I think that's obvious, but my question was about the relative contributions of air temp, insolation, wind driven advection to warmer waters, etc. Air doesn't have a lot of thermal capacity (relative to ice), but there is a lot of it (relative to ice), so the equation comes down to how efficiently warm air can dump its heat into the ice and then move on. The question is relevant to Greenland, as well, where it seems that insolation and albedo have more to do with surface melt than air temperature. But all factors contribute -- so I'm trying to learn what those relative contributions are.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 25, 2014, 04:55:39 PM »
I know everyone is super excited.
Not to distract this discussion, but I have to add that the SMB maps are telling a quite different story than NSIDC when it comes to the severity of recent GIS melt. Top 10 might not be too far off after all.
Agreed. Here are the SMB daily/cumulative plots from today. Given that the average is the already-warm 1990-2011 years, this is some pretty significant melt. The runoff must be absolutely gushing out of the ice. When you add the rate of glacier flow, this is going to be another year of significant mass loss.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 25, 2014, 04:28:45 PM »
Ice meet boot:

Could be spectacular melt but we will have to wait and see if this forecast for temperatures over  the basin materialize.
I'm a little unclear on what the temps really mean in terms of melt. It seems to me that the high pressure systems that bring the warm temps also bring clear skies (i.e., more insolation) and wind patterns that push ice outward, spreading it out (and southward) and making it more vulnerable to melting. But ice, as people have been pointing out of late, is a good insulator, and the thermal coupling between the air and the ice is fairly poor. So for a (relatively) short term event like the coming (predicted) high pressure systems how much of the melting is the result of air temperature and how much is the result of other factors? I'm sure the answer is known, I just don't know it.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 24, 2014, 04:50:21 PM »
This is quite interesting, but wouldn't the same/similar effects likely occur in reverse in the summer, i.e. that the ice tends to melt faster the less of it is there is? It seems like your argument sort of boils down to the idea that it's easier to form new ice than to melt it, but is that what the underlying physics really suggests?
I think you make a valid point. The warmer the winter, the thinner and warmer the resulting ice. When it comes to the melt season, thinner, warmer ice will start to melt sooner. When you add the warmer summer, plus all the heat the ocean is absorbing globally (and the arctic ocean in particular absorbing ever-warming runoff from the continents), you get more melting. As the polyna's become larger, the water absorbs even more heat -- a positive feedback. All of these processes are ongoing -- every year a "little" more heat is added to the global system. (E.g., June had the largest SST anomaly for any month, ever.) That's why I don't see any slowdown in our future -- at least until and unless global warming reverses.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: July 24, 2014, 04:19:53 PM »
It is not my imagination; the flow of water and ice is literally dividing that long 2000KM2 "Knife" of fast ice that broke off a week or so ago; half is moving east, half west.  There is something extraordinarily strange happening there.

Let me add, it appears to be melting FAST.  In the animation you show, upwards of 20% of the ice has disappeared in just that time span.  That was thick land fast ice.  There's a powerful heat source at work there.  Where do we think it might be coming from?!
My take on it after watching the animation for a while is that there is a warm current upwelling in that area. It's clearing out that open area, and melting anything that lingers.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 24, 2014, 03:02:35 AM »
It seems to me that your argument is that since the MYI is mostly gone, we've basically shifted gears into a new quasi-stable equilibrium, and are now approaching "ice free" asymptotically rather than exponentially. Is that a fair characterization?

Broadly speaking, yes.

Got some niggles about the use of asymptotic, but I get why you use the term.
I don't particularly agree with your assessment, but I can see why you would come to that conclusion. I guess time will tell. We should probably agree on what "ice free" means, beforehand, though. I mean, it's going to be hard to get to 100% ice free waterways with Greenland sitting there dumping gigatons of thick ice into the ocean all year every year. But when do you stick a fork in it? At 95% extent reduction from, say, the 1980's average? Or maybe 98% volume reduction? I'm not really sure myself -- but I've been thinking along the 95% or 98% lines. At that point it's unmistakably a new world (not that it isn't already, but you get my point -- nobody could look at it and claim "natural variation").

Arctic sea ice / Re: The 2014 Melting Season
« on: July 24, 2014, 02:45:49 AM »
If that happens the ESS is in a wee bit of trouble in a hurry.

The fast ice will go POOF.
The ESS fast ice is pretty much going POOF already. If that projected heat hits, the whole ESS is going to go POOF.

On the bright side, if your and BFTV's high pressure materializes, we might get the first good, cloud free, view of the Pacific side that we've had in weeks. If you can call that a bright side.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 23, 2014, 09:38:59 PM »
Check out the graph plot on this image:
Unless one takes the last two years as the new trend, an extrapolation of those curves says that the 4-years ice is basically done (i.e., down to a couple percent, which is likely less than the uncertainty in the measurements), the 3-4 and 2-3 year ice is pretty much the same plus or minus a year or two. That really only leaves 1-2 year "MYI" in any quantity and that's maybe 10% to 20%, which could easily get taken out in a warm year -- heck, it could all just float out through the Fram if the wind blows hard enough.

It seems to me that your argument is that since the MYI is mostly gone, we've basically shifted gears into a new quasi-stable equilibrium, and are now approaching "ice free" asymptotically rather than exponentially. Is that a fair characterization?

Arctic sea ice / Re: The 2014 Melting Season
« on: July 23, 2014, 06:21:50 PM »
But that's my key point; the ice will not continue to thin as fast as it has done. We've lost all of the MYI that can be lost given that the ice doesn't melt away totally in the summer, now we have a residual MYI in a mainly first year ice pack. The thickness of the FYI is set by thermodynamic thickening over the winter.
I guess I don't get your point, then. If all the ice is first year ice then, by definition, the ice has completely melted out the previous summer. If the ice isn't all first year, then there remains some MYI, and the volume decrease can continue.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 23, 2014, 04:52:08 PM »
Chris, I don't see any reason for the rate of summer melt increase to flatline, slow down, or even be linear. As the ice thins, the surface/volume ratio increases, which should increase the rate of melt. The thick MYI held off major assaults in 2017 and 2012, but that ice is nearly gone. What we have now is this "mesh ice" that spreads out as the edges melt (which, though it is a negative feedback (because it keeps more of the ocean covered with ice), is a short-lived one). That spreading increases the surface (both top and bottom) that can melt.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: July 23, 2014, 04:25:18 PM »
Interesting melt day. By extent there are no surprises, Kara sea ice continues its disappearance and small changes in other regions. By area there are big declines from different sides of the Arctic: Beaufort, ESS, Kara and the CAB. It looks to me that different reasons for this, cyclonic activity over teh Beaufort, strong southern winds in the Fram Strait and maybe warming on the Siberian side.
A couple of days ago I mentioned in a post on the melting thread that the drift maps were predicting something like this. Conditions were pushing ice into the open water areas around the arctic. This results in little decrease (or even increase) in extent, but as the ice spreads out, concentration drops (which affects area). Based on your results, I'd say melting is proceeding at a rapid pace, but is being obscured on the extent plots by de-compaction.

Yesterday's drift map is attached.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 21, 2014, 11:36:22 PM »
Thanks, Chris, that's a great summary. The graphs are really helpful -- and they show just how variable each region is from year to year. I think that demonstrates that the local and regional weather patterns are a big factor in what will melt and when. Even 2012 had regions where it was slower than other years. And even 2014, which has so far had pretty mild weather, leads the pack in some areas.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 21, 2014, 07:44:23 PM »
Looks like the ESS fast ice fell apart when we weren't looking.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 21, 2014, 07:40:07 PM »
According to NOAA, June was the hottest on record, making two months in a row.
Ugh. We're not even in a full blown El Nino yet, and the sea surface temperature anomaly was the largest ever recorded.

Good thing we don't need the oceans for anything, otherwise we might have to worry about their ecosystems.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 20, 2014, 09:24:56 PM »
If the drift maps are correct, then the next week sees ice pushing from the central regions into most of the open water areas: Beaufort, Chukchi, Laptev, Barents. If that happens, we should expect to see increases or very slow decreases in extent, but decreases in concentration.

Too bad its so cloudy, it would be interesting to watch some of the process in action.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 18, 2014, 04:31:19 PM »
Robert Scribbler has posted an article discussing the intensities of the ongoing wildfires in Canada and Siberia, going full circle with how this has roots as far back as this winter with the high pressure ridge.

My primary response right now... literally... is a sinking feeling in the pit of my stomach.
Sort of a beginning of the end kind of feeling, huh? It's incredibly depressing to see so much destruction, and then to know that it's only getting started. There will be years ahead that we'll look back on this as the good old days.

Arctic sea ice / Re: The 2014 Melting Season
« on: July 17, 2014, 02:46:55 AM »
Speaking of the big crack, it is definitely showing renewed signs of life. A little hard to see through the clouds, but unmistakable. A couple more days of this drift pattern and we're likely to see something interesting. It's already at least 10 miles wide in some spots, and with a bit more of the same conditions you'll be able to sail from the Beaufort practically to Greenland. Who needs a northwest passage when you've got the Big CrackTM?

Edit: note that the two images are from different sources, so the second image is rotated counterclockwise relative to the first.

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