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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 2 days ago 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.
Rob D, "...high variability that comes with weather sensitivity of ultra-thin ice..." sounds like a good capsule description of the 2013 melt season - and as you imply, yet another instance where the models may need to play catch-up. We're seeing another manifestation just recently: as Neven observed in the OP, "...a large part of that record amount of first-year ice at the start of the melting season has been preserved..." So there is more remaining to melt towards the end of the season (from more conducive weather, bottom melt, wave action etc.) and the declines in area and extent are relatively steep for this time of year. I expect that PIOMAS will also have a drop in anomaly over the next month or so.
Toggle Commented Sep 10, 2013 on PIOMAS September 2013 at Arctic Sea Ice
Rob and Wili, There was some lively discussion of the "rebound" topic last year at http://neven1.typepad.com/blog/2012/05/arctic-sea-ice-loss-and-the-role-of-agw.html?cid=6a0133f03a1e37970b01630551734e970d#comment-6a0133f03a1e37970b01630551734e970d, referring to a paper by Tietsche et al that found recovery over a two-year interval following a shock. See also Chris Reynolds' discussion at Dosbat http://dosbat.blogspot.co.uk/2012/09/sea-ice-albedo-changes-and-seasonal.html of the Notz and Marotzke paper on AGW vs. other factors. The evidence of 2013 is for two different causes: a rebound early in the year, probably owing to heat loss from open water at the end of the previous melt season, and later a slow melt from cloudy and cool conditions. Whether the latter is natural variability or a longer AGW-related causal chain, as Jai Mitchell suggests, is a good puzzle for the scientists. [fixed links; N.]
Toggle Commented Sep 8, 2013 on PIOMAS September 2013 at Arctic Sea Ice
The excellent series of annotated maps posted by BornFromTheVoid over on the forum raises the question of whether this storm will cause a large area of sea ice to detach, as did GAC-2012. Inferring from wind direction over the next few days together with Coriolis apparent force, a notable candidate is the swathe of relatively thick ice N and E of Severnaya Zemiya. With the current storm less intense and widespread than last year's, and the ice less primed for detachment, I would not expect this area to cut loose in the few days following the cyclone.
Hmmm, the thicker ice (relative to last year) in the Kara Sea is sandwiched between anomalously warm water to the west, on the other side of N.Z. island, and early loss of snow cover to the southeast in Siberia. Wonder how long it will hold out.
Toggle Commented Jun 9, 2013 on PIOMAS June 2013 at Arctic Sea Ice
Peter, your counterexample is flawed on two counts. First, the mean significant wave height averaged over the Mediterranean Sea is less than 1.5 meters, even in winter. Second, if you look at the animation above, it's clear that the ratio of ice edge to water area in the freezing region is far higher than it would be under normal freezing outward from the pole. Your views seem to be at odds with oceanographer Luc Rainville, who was quoted in Discovery News as saying that sea ice muffles all waves "like a big damper."
Toggle Commented Nov 12, 2012 on Bilateral freezing at Arctic Sea Ice
hmmm, it seems that the surrounding ice would reduce wave action in the enclosed open water. This would cause 1) faster re-freeze in that locale; 2) smoother surface, probably even more than is normally characteristic of first-year ice. If the smooth area survives ice pack dynamics during the winter, it would have different ponding behavior the following spring. See the Perovich & Poshenski study on how FYI differs markedly from multi-year ice in its seasonal albedo and melt pond formation. SekeRob commented on the latter; "...it's nice and smooth and promotes much larger and interconnecting ponding than ... MYI." In a similar vein, Flocco et.al. in JGR found that ice beneath ponds melts up to three times faster than bare ice. Higher melt rate, earlier start. You can see this as a steep downslope in the anomaly graphs. There's a lesser but still reinforcing factor that Lodger pointed out in the _PIOMAS September 2012 (minimum)_ thread: Earth' solar aphelion comes after the northern summer solstice, so ToA solar irradiance is slightly higher before the solstice than after. This consequence of the Earth's elliptical orbit multiplies the effect of lower albedo early in the melt season. So there are two trends that appear to go in in opposite directions, on just slightly different timescales. The first is widening seasonal percentage swings in sea ice area, as illustrated by Jim Pettit's graph. crandles noted one possible cause in an earlier post: "One way you can get more ice at maximum in the seasonally ice free version is that it misses out on autumn/fall snow cover which is excellent insulation compared to just ice." On a y/y time scale, Arctic ice extent (though not volume) has had a one-year negative autocorrelation. For some discussion sans consensus, see the thread _Arctic sea ice loss and the role of AGW_. I think Chris R also addressed the topic in his Dosbat blog. This rebound behavior - especially following record ice loss years - is one reason Notz & Martotzke ruled out self-acceleration as a dynamic in sea-ice cover. (see their Figures 1(b) and 1(d), paper available here.) The correlation seems to have weakened in recent years. For September extent, if not for March, it may have even flipped to positive. A big question for 2013 is whether the recent pattern continues. The combination of trapped heat (noted above by Apocalypse4Real) and lower albedo from earlier and more widespread ponding seems to favor another extreme low in sea-ice cover. That could be a harbinger of self-acceleration taking hold. "Accentuate the positive," as the happiness researchers like to say - except here we are dealing with climate feedbacks.
Toggle Commented Nov 12, 2012 on Bilateral freezing at Arctic Sea Ice
I was wondering how the climate models fare at predicting minima, and how much improvement CIMP5 shows over CIMP3. Haven't found anything conclusive, however... The CIMP3 models, used as the basis for the IPCC AR4 (2007) report, were way off but in a surprising way. If you look at the month-by-month model values (Fig 1 in Stroeve et.al. 2012, http://www.agu.org/pubs/crossref/2012/2012GL052676.shtml), their errors vs. observed mean increase markedly from January through April. So where reality wrong-footed the models was not so much the amount of peak-to-trough melt (by area/extent), but the lack of re-freeze afterwards. The CIMP5 ensemble has a similar monthly pattern of errors - at least on data through 2011 - though to a lesser degree. This reinforces the idea that we need to figure out what caused the melt anomalies to shift earlier in the season.
Toggle Commented Sep 9, 2012 on Minimum open thread at Arctic Sea Ice
Great post, Chris. btw I think you mean "if the surface temperature rises, that heat flux reduces... " The hunt for a sole silver bullet is tantalizing. But if we assume that the big volume drop in 2010 was caused by an interaction among several elements rather than mainly by a single one (such as WACC), we may find other clues implied by successive y/y changes. Re: FYI frozen onto bottom of thick ice - during the the day 140 - 170 interval, aren't we looking at slower formation of this FYI rather than faster melt? In the month before the solstice, total volume has been roughly flat in recent years, while area/extent accelerates downward: so freezing must be occurring within the pack. If so, the lower heat flux through thicker ice would support crandles' hypothesis, not counter it. Maybe comparing the time-shift in downtrends will yield some insight. Following the big drop in ice thickness in 2007, the downslope in volume anomaly has been earlier and/or steeper than before. This seems consistent with either less-rapid freezing of FYI under thick ice (each passing year, less MYI where this can form) or with more rapid progression of edge melt from the peripheral oceans to the Arctic Basin (@Chris R 3 September 2012 10:22 on Dosbat blog). Comparing to the volume/area chart, http://tamino.files.wordpress.com/2012/09/thick_yy.jpg there's a deviation from Feb-Apr 2010 that seems plausibly explained by WACC. But as pohjois noted in the Tamino blog, "it is year 2009 which is the first example of the new regime – maximum early in the season..." So it looks as though WACC was additive to some influence on ice thickness that was already operating in summer 2009, with possible foreshadowing in prior years.
Terry, good point on multi-year ice. In addition to more portals for advection as the archipelago fastness weakens, there could be a snow-cover mechanism for self-acceleration. This from a Nature Climate Change (July 2012) piece summarizing Perovich and Polashenski (Geophysical Research Letters 39), which Neven referenced in the Arctic sea ice loss and the role of AGW thread: http://www.agu.org/news/press/jhighlight_archives/2012/2012-05-15.shtml#three "Seasonal ice tends to accumulate only thin layer of 5cm of snowpack [vs. 20-30cm for MYI]... melts more quickly in the early summer, revealing ice and melt ponds... albedo of seasonal ice drops to 0.3.... Over the course of the entire season, nearly 40% more energy enters an ocean system with seasonal sea-ice cover than one with multiyear ice..." Chris R, the indicator that Notz & Marotzke use is whether a strong excursion is followed by a reversal. (Granted this is a bit simplistic, as self-acceleration mechanisms could operate on a periodicity of longer than one year - or shorter). The big YtY drop was in September 1997; '98 is significant for the lack of reversal. However, that series was an isolated instance until recently. So I agree with their conclusion, on data through 2010, that external forcing - namely CO2 - was mainly driving sea ice loss. The question is whether the last few years will prove to be the beginning of a persistent SA influence. I see this topic has already been pretty thoroughly thrashed in the AGW thread back in May, so I'll wait for the experts to parse the latest data. Ice volume is probably a better indicator than area/extent, as you and others have argued. However, as volume trends down, there is less latent heat of fusion to carry the memory signal from one year to the next. So we need to look for other heat stores (e.g., R. Gates on thermal gradient across the ocean skin layer) and other possible mechanisms of SA - if the melt continues beyond what external forcing would cause.