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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.
Are these contradictory or complementary observations? @ Blaine (in the PIOMAS thread) "Incident sunshine was quite high in 2014, probably even over the 2007-2012 average .... we had much lower heat transport from land into the sea ice near the coast than in other recent years." @ Jai Mitchell "Apparently the insolation intensity of late spring and early summer periods are the dominating factor determining the rate of latter year ice melt." "you may notice that the majority of the anomalous injection of pacific water vapor took place between May 10th and June 13th." It sounds like Jai is talking mainly about latent (rather than sensible) heat advection from lower latitudes. Whereas Blaine (and I) may be influenced by recency effect, with more high pressure and insolation later in the melt season - but with circulation patterns that tended not to pull heat into the Arctic. Reconciling the two would reinforce and add detail to Neven's earlier conclusion about the importance of early conditions to the melt season as a whole. Jai also mentions fog cover; there was some earlier discussion on the forum (unresolved AFAIK) about how much impact this had on surface temperatures and melt pond formation.
Thanks for another great post, Neven, in particular the reminder of the effect of a Beaufort high on timing of the minimum (extent?). I doubt this year's will be as late as in 2010 (sticking with my earlier prediction of 14th Sept) - but hey, if I'm wrong, that just makes life more interesting. Minor point, for the NOAA/ESRL/PSD/NCEP surface air temperature map I suggest using the 7- or 30-day anomaly, which would be more consistent with other elements of your update than the 1-day.
@Jai Mitchell Not to disagree with any of your discrete observations, which I'm sure are accurate and well-informed. And "... an increase in mid-latitude water vapor entering the arctic, leading to increased relative humidity, cloud cover and cooler temperatures" makes sense. I'm curious whether it also relates to fog cover (if in fact spring or summer 2014 was unusually high) and if the timing would have affected melt pond formation. However, my lay impression is that for this melt season as a whole, atmospheric patterns and attendant pressure gradients resulted in less-than-normal heat advection into the Arctic from lower latitudes. Do you know of any aggregate data that show the opposite?
Toggle Commented Sep 11, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Quoting Chris R from the forum: "I don't know if anyone has pointed this out, but 2014 saw the second smallest PIOMAS volume loss from 1/6 to 31/8, only 1996 was lower." I'm baffled, but it's worth brainstorming some factors and seeing whether we can piece together a causal chain. Compactness (especially in the main body of the pack) seems to be important, probably related to relatively low pressure gradients during most of the melt season. (Now that the cyclones are stirring, does this portend an atypical September drop in volume?) Also related to light winds, there was some discussion earlier about temperature inversion and fog, which would reduce insolation at the surface (crucially, around the solstice). There might be some other, seemingly minor but disproportionate factor - I recall mention of a light snowfall that might have had just the timing to retard the onset of melt pond formation.
Toggle Commented Sep 7, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Another thorough and thoughtful summary. With its lack of pressure gradients and attendant ice transport, "the year of in situ melting" is a good capsule summary for 2014. btw under SIA I think you mean "...that massive melt pond refreeze on the Atlantic side of the Arctic..."
Toggle Commented Aug 24, 2014 on ASI 2014 update 8: neck and neck at Arctic Sea Ice
@ Chris Reynolds Pete, "Pre-anthro-forcing did ice melt differently?" The most recent peak in summertime insolation was around the time of the first anthropogenic forcing, if it's true that land use changes from agriculture and grazing affected climate. By the time of the industrial revolution, it had dropped off at the higher latitudes. We're lucky we didn't "poof" all those fossil fuels during a time of increasing insolation. The graph is from www.realclimate.org; cites Source: Marcott et al., 2013.
Toggle Commented Aug 9, 2014 on Poof, it's gone at Arctic Sea Ice
On a geological time scale of "poof", we're already at the first "o".
Toggle Commented Aug 4, 2014 on Poof, it's gone at Arctic Sea Ice
@ Rob Dekker Thanks for the updated graph and prediction, Rob. I will be surprised if the impressively low SD of your method holds up in coming years, given increasing fragility of the sea ice and its susceptibility to many other factors. As for this year, it looks like the snow cover and melt pond predictors are pointing in opposite directions. My leanings are toward the latter, though the Arctic counsels an open mind.
Toggle Commented Jul 3, 2014 on ASI 2014 update 4: high times at Arctic Sea Ice
@ Rlkittiwake If the CICE simulation is correct, the trend in recent years has been toward earlier pond formation and greater surface area (the latter relates partly to Neven's point about FYI). While the CICE graph doesn't show latitudinal distribution, it's likely a good bit of the increased ponding is at higher latitude: see Werther's mention of CAB among other regions. That's three multiplier effects in the positive feedback.
@ Werther "Why would the sea ice in the Beaufort Sea be less conducive to melt pond formation now?" I haven't compared current conditions, but in Neven's 2013/2014 Winter Analysis post last month, March/April 2014 shows older, thicker, and more deformed Beaufort ice than in 2013. I've also seen recent mention on the forum of snow cover on the Beaufort ice. Can anyone point to analysis of this factor? My understanding is that snow cover is conducive to melt pond formation under some conditions (flatter ice surface, warmer temperatures) but not others.
@ Werther Yes, the big wild card in the near term is ice pond area. The multi-year ice in the Beaufort should be less conducive to melt pond formation. But if the forecast proves out, a few days later warmth and sunshine extend to the CAB, where the (presumably flatter) ice will form larger ponds. And that's at higher latitude, which for the next month or two means greater insolation as a multiplier effect to lower albedo. "On melt ponds, I never had the impression that May would show the first important growth of these." I've seen differing data. The CICE simulation shows a peak area in mid-July, though trending earlier in recent years. Rosel & Kaleschke figure 3b indicates earlier, as does inference from CAPIE. There's a recent paper by Marko Mäkynen using data from the late lamented ENVISAT that might clarify timing. What matters for the total heat budget, though, is not so much the timing of the peak in pond area as the integral over the cycle. So a late start can still retard the entire season - I think Schroeder found May data to be the most predictive (Fig. 3 in September Arctic sea-ice minimum predicted by spring melt-pond fraction; see also discussion in More on melt ponds blog post.) It would take quite a spike in the next week or two for 2014 to catch up on this count.
@ Jai Mitchell "I believe that cloud seeding forces latent heat back into the oceans. . .right?" meaning the latent heat of condensation when cloud seeding causes precipitation? Most of that is released into the atmosphere. Some fraction goes into the water droplets that form. But the amount the rain adds to ocean water would be secondary compared to the loss of latent heat from surface evaporation in the first place. My lay reading of NOAA reports etc. is that " increased rates of energy deposition" has been mainly in subsurface layers: increased evaporation from anomalously warm surface waters raises salinity; denser water sinks, moving sensible heat downward... until the next Kelvin wave. Some cool stuff in your new thread on the forum btw.
Toggle Commented May 31, 2014 on Greenland 2013 in review at Arctic Sea Ice
"Fast ice holding the river back actually increases the effect the river has on sea ice retreat." That could be a (minor) factor in the negative one-year autocorrelation that appears still to be in effect.