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Good catch Lodger, thanks for the correction. I wonder whether there is some way to derive data from the Tschudi ice age model to quantify the change in MYI melting within the Arctic vs. being exported. The animation on certainly supports your point. Rob, generally agree with your assessment, though it omits the unknown (and possibly greater) influence of snow cover over sea ice. Would that we had better observational data.
At this late date and under near-neutral conditions, it shouldn't be too hard to pick a number. But I'm still baffled by the factors in opposition: concentration vs. thickness distribution, among others. Thinking on a V-shaped extent minimum, which would require compaction continuing beyond next week and a further push from bottom melt. So I'll guess 4.1 million km2 for the JAXA daily min you linked to. Interestingly, on the other poll's measure of NCSID September average extent, the SIPN August Report's median of 4.54 million km2 is up slightly from July's, but still low enough for a 3rd-place finish.
Yes, less alarming than it looked a couple of months ago. Yet volume anomaly still hit a record low during June. And as others have noted on the Forum, the picture appears worse if you give any credence to inferring volume from Hycom. Further to Jim P's projection, one question is what path volume might follow to a new record minimum. Based on the thickness distribution, it looks like July would run ahead as the Atlantic-side melt picks up pace, followed by a slower August (that is, volume anomaly would turn up more steeply). OTOH if low-pressure systems predominate, they would give the central pack some measure of protection during July (which looks to happen in the coming week or so). But a deeper low during August would intensify wind-and-wave melting. I'll refrain from guessing on this one: depends on the weather.
Toggle Commented Jul 5, 2017 on PIOMAS July 2017 at Arctic Sea Ice
@DavidR, Good reasoning to bias the projection toward more recent years. Archimid's graph of volume gain during the freezing season (post #1726 in ASIF PIOMAS thread) shows an increasing trend with a possible step-change around 2008. Conversely that implies even larger peak-to-trough losses since then. Also iirc, Chris Reynolds argued for a regime change in ice dynamics following the extreme 2010 volume loss. Eyeballing Wipneus' PIOMAS chart, there seems to be a tendency for the largest (negative) volume anomalies to revert more. But it's not at all consistent, and doesn't necessarily happen before the melt-season minimum. No sign of reversion at all so far this year.
Toggle Commented Jun 4, 2017 on PIOMAS June 2017 at Arctic Sea Ice
Good summary of a critical metric at a pivotal time. One thing that catches my eye is the range of trajectories in Jim Pettit's graph. If a neutral expectation for volume minimum is in the middle of the pack, a regression assumption (i.e., moderation of the current extremely low anomaly) would land somewhere above the middle: safely higher than the record low. But it doesn't feel like that assumption is valid this time. Low average thickness, thicker ice heading for the exits, and the seeming likelihood of melt ponding over first-year ice that extends well into the pack... not good at all.
Toggle Commented Jun 3, 2017 on PIOMAS June 2017 at Arctic Sea Ice
The nearly-unchanged anomaly is bad, the flattening thickness graph is worse, and the spatial distribution - if PIOMAS is even approximately correct - is terrible.
Toggle Commented Apr 5, 2017 on PIOMAS April 2017 at Arctic Sea Ice
"Eggbeater August"
Toggle Commented Aug 19, 2016 on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
This is a good analysis of the puzzlingly high melt rates - especially on AMSR2 data - under what seem to be middling weather conditions. As for sea surface temperatures, the current distribution seems more favorable for ice retention than 2012 or 2015. This coming week again looks to bring relatively low heat advection from Kara/Barents (except for a couple days of rain over Laptev) or from south of the Bering Strait.
Toggle Commented Jul 21, 2016 on ASI 2016 update 4: breaking point at Arctic Sea Ice
The ice motion anomaly graph is quite useful; corroborates the explanations others have given for more thick ice in ESS and Laptev. Also noteworthy that volume hit a record low this spring despite lower-than-average Fram Strait export. This underscores the dominant influence of the warm winter.
Toggle Commented Jul 7, 2016 on PIOMAS July 2016 at Arctic Sea Ice
Edit: Wayne, I see that Neven's response above is more on point to your question. The anomaly graph on Wipneus' PIOMAS page shows how volume differs from the historical average for each day of the year. This highlights the volume counterpart to the "June cliff", discussed elsewhere (more in reference to area or extent, iirc). OSweetMrMath's is the next refinement - he gives a good explanation; I think of it as "How is daily volume different than it would be if the year were in line with both the seasonal cycle and the long-term trend?" See also Tamino's similar treatment for ice extent:
Toggle Commented Jun 8, 2016 on PIOMAS June 2016 at Arctic Sea Ice
@ Wayne Kernochan If I understand your suggestion correctly, that's just what OSweetMrMath did on the PIOMAS thread on the forum (post #914). His detrended anomaly graph is fascinating.,119.900.html As for the conventional anomaly graph above, 2016 has tracked fairly parallel to 2014 so far. My guess is this will continue in June (i.e., anomaly falling but at slower rate).
Toggle Commented Jun 8, 2016 on PIOMAS June 2016 at Arctic Sea Ice
Although I take Rob's numbers seriously, I disagree with his conclusion. First, some fraction of the insolation heat will go into the atmosphere and be carried over the Chukchi and beypnd. Second, with area/extent in the Beaufort already far below normal, the graph is likely to flatten soon as the gyre moderates and temperature anomalies become less extreme. So the coastal ice that Neven highlights, as precarious as it looks for the next few days, is more likely to hang on through most of June.
Toggle Commented May 22, 2016 on Beaufort final update at Arctic Sea Ice
Thanks for advocating for observation-based melt pond research, Neven. We really need that early-warning system. I like Yvan Dutil's suggestion of crowdfunding, but am not sure there's sufficient interest outside this and other like-minded communities. Maybe the wealthy homeowners of Miami Beach and Mumbai will kick in?
Toggle Commented May 7, 2016 on EGU2016, my impressions at Arctic Sea Ice
It will be interesting to see the timing of the coming downturn in Barents relative to blips upward in Greenland and Okhotsk. The real wild card, though, is the large proportion of thin ice in Baffin/Newfoundland and what fraction of the recent melt/compaction crosses back over the 15% margin later this week.
Toggle Commented Mar 24, 2015 on The Ns are calling the maximum at Arctic Sea Ice
There's a lot of ice cover close to the 15% cutoff in Baffin and St. Lawrence, and increasingly in Bering. All three regions show a recent divergence between JAXA and UH AMSR2 in Wipneus' charts. The former appears to be counting extent near the fringe in places where the latter is not. This has occurred in prior years, probably owing to differences in grid cell size.
Toggle Commented Mar 23, 2015 on Early record, late record at Arctic Sea Ice
Can't say for certain that we'll have the final answer within a week, even though it's quite late in the season. Conditions look favorable for extent increases for a few days around the 25th. It's quite possible the number will be just below the 15th Feb peak and nosing up toward it - rather like a polar bear cruising beneath the ice, getting ready to pick off a hapless seal on the surface.
Toggle Commented Mar 18, 2015 on Early record, late record at Arctic Sea Ice
Looks like conditions are in place for an early volume peak: high anomaly, above-normal air temps in the forecast, and lots of ice getting pushed out into warmer waters during the latter part of March. I'll put in a guess that the max arrives the first few days of April, which would be earliest in recent decades if I'm reading PIOMAS graphs correctly.
Toggle Commented Mar 14, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Interesting that this year will have either the earliest extent maximum or (perhaps) the latest. It's an extreme instance of a sinusoidal characteristic that OSweetMrMath pointed out on ASIF: the function is flattish near its maximum, which makes the timing hard to predict.
Toggle Commented Mar 13, 2015 on Mad max? at Arctic Sea Ice
edit: gains in Bering not Barentsz
Toggle Commented Mar 12, 2015 on Mad max? at Arctic Sea Ice
@Neven "Plenty of snap potential, but first all of this 'heat' (it's temperature anomaly, so still plenty cold, just not megacold) needs to get out of the way, and by the time it does, it'll probably be too late for a snap:" This will be entertaining to watch. A week from now the extent gains in Barentsz and Baffin/Newfoundland will be trailing off or reversing. Looks like not much contribution from Okhotsk by then. Meanwhile an extent drop in Kara from melting and compaction. Will Kara refreeze before the newly-formed thin ice melts elsewhere?
Toggle Commented Mar 12, 2015 on Mad max? at Arctic Sea Ice
The animation is indeed quite striking. Someone posted a statistic on ASIF a while back of the percentage that Fram export accounts for of total annual peak-to-trough volume change. I don't remember the number but it's fairly small (~10%?). However, it seems likely that Fram export can have a disproportionate effect on the melt season. A strong export in the spring, for example, would thin out ice in the central basin and make it more susceptible to insolation.
Toggle Commented Dec 27, 2014 on Fram Strait 2014 at Arctic Sea Ice
Good post as usual, Neven. When considering the linear anomaly trend by itself, the excursion into +2 STD territory is remarkable. In another sense, it's an eventuality if a sigmoid function is taking over as a better representation of reality, as Chris R and others have asserted. Anyway my guess is that November will mark the anomaly peak for the near term, as above-normal Arctic temperatures exert a delayed effect on the refreeze, and Fram Strait export picks up markedly.
Toggle Commented Dec 7, 2014 on PIOMAS December 2014 at Arctic Sea Ice
It did change in slang usage: "I ain't got nobody...." Anyway looks like nothing especially post-worthy so far during the refreeze season. The 80* temperature anomaly has been rather high, but I suppose that's not so unusual in the post-2007 ice era.
Toggle Commented Oct 22, 2014 on PIOMAS October 2014 at Arctic Sea Ice
@ Leslie Graham I don't think Neven was necessarily mistaken in trying to engage earlier in the thread - despite the outcome. If someone appears genuinely open-minded, and happens upon some of the abundant misleading information or discredited views available, it could be worthwhile to show them the basis of mainstream scientific thinking. Note that one of the major contributors on ASIF admits to being a former climate sceptic.
@ Blaine I'm impressed (if not entirely convinced) by your observations and conclusions based on OLR as a proxy for cloud cover. The points you and Jai bring up probably go a long way toward explaining seasonal and even interannual variability in ice cover. Good topic for a separate blog post or dedicated forum thread. My sense is that we will need to take a more granular look at both timing and location of water vapor incursion from lower latitudes, as effects cloud cover and particularly melt pond formation.