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epiphyte
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I think that there are at least two variables which are not being considered when trying to correlate June melt pond fraction with September area/extent. The first is snow cover, - one might speculate that snow changes in volume more quickly than ice, allowing voids to form on top of lower-lying areas of the ice surface, which can fill with water to become ponds. This prompts the question "what if there isn't any snow?" (as was the case with much of the anomalously low June melt-pond area depicted for 2015) The second is the ice surface topology. Most of the ice which had anomalously low melt-pond fraction in June is FYI which formed is Sep/Oct/Nov/Dec last year - it therefore has a relatively uniform surface with no ready-made depressions in which liquid water can accumulate. Considering the above it seems to me very likely that the June melt-pond fraction won't be a reliable prognosticator this year... ...and I think that this is starting to become evident even from just eyeballing EOSDIS/worldview. E.g. Look at the current state of the CAB north of Laptev at around 85 degrees N - there's a large area which looks similar in condition to fast ice in the southern laptev just before it dissolves into nothing. There's a slightly less dramatically rotten, but huge, area along a 100 mile long strip running E-W north of Greenland - just above the boundary between MYI & FYI. I guess what I'm trying to say is, we know that this year weather has strongly favored melt across much of the arctic. We can't see it but that doesn't mean it's not happening. We don't have direct instrumentation over most of those areas - and none in FYI. We rely instead on proxy observations, such as melt ponds - but this might cause us to be misled because they are only reliable if we've considered all the variables. Just going by the weak winter (over the CAB, at least), and the strong summer, and the evident mixing of air and water between the northern and southern latitudes, conditions have been just about perfect for creating a huge surprise for anyone who relies on estimates of ice formation and melt progress which were validated in an earlier era. Unfortunately, that's all of them. So as seems to have become a habit of late, I'm not saying it's this year it largely goes poof - but I haven't yet seen anything to rule it out...
Toggle Commented Jul 18, 2015 on Junction June 2015 at Arctic Sea Ice
@Bill_Fothergill - "The ice very close to the ice/water boundary will of course be at a temperature very close to that of the water, and it will be clamped there by the massive thermal inertia of the surrounding ocean" So here's what wakes me up some nights... If I understand it correctly, the entire arctic ocean has a temperature profile which is inverted w.r.t other bodies of water. - elsewhere, surface water is warmer that that below - but in the arctic , the surface is less dense because it has lower salinity, so it can stay at the top even though it is colder than the higher salinity water below. ...but isn't the inversion caused by the ubiquitous presence of ice on the surface? If so at some point will it flip - and all the energy that is currently lurking below 50M will suddenly become much more relevant?
Toggle Commented Apr 21, 2015 on CryoSat-2 sea ice thickness maps at Arctic Sea Ice
How's this for a hypothesis? - In the current regime of flat, predominantly 1-2m ice, Feb-mid-April area/extent volatility in ESS, Beaufort, Chukchi and CAB cause the total volume at maximum to be larger in those core areas than it would be given continuously unbroken cover, because ice grows more quickly over open water than over an insulating layer of pre-existing, snow-covered ice. When this happens it becomes less likely that there will be open water in these areas late in the melt season, which means a larger minimum. If that makes sense, things could be interesting this year, because it seems that the low overall minimum was realized in spite of the low volatility in the core areas, not because of it. I.e. all of the anomaly was early, at the periphery, with static area/extent at the core, leading to both the long area/extent plateau throughout March that many have noted, and lower total maximum volume in the core than would have been the case had it started the year in an already fragmented state.
Toggle Commented Apr 4, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Chris Reynolds writes: "Thanks Epiphyte, and thanks to Neven for re-blogging. I don't see this as having any impact on the fate of the whole pack though, such rapid disappearances are not uncommon. PIOMAS volume holds no surprises, now above 2007." ...Please don't get me wrong. I wasn't trying to say that thin ice in favorable conditions is disappearing any more rapidly than it has in the past. I'm just trying to illustrate the argument that as the pack grows more uniform in thickness, more fragmented and diffuse in extent,more mobile and more subject to incipient energy from outside the arctic, the larger the fraction of the remaining ice that is at risk of melting at any given moment. PIOMAS is a case in point. From what I can see, almost everywhere PIOMAS modeled a significantly lower June-July melt anomaly in 2014 vs. 2013 is now open water - which makes me less inclined to rely on it as a guide to what's coming next.
Toggle Commented Aug 6, 2014 on Poof, it's gone at Arctic Sea Ice
"Would that be the perfect melting season for getting the Arctic close to ice-free?" epiphyte here - (Can't figure out how to use my favorite pseudonym on this blog... Ah, well...) It seems to me that there might already be enough energy in the mix to melt all of the ice - but the many antagonistic mechanisms playing tug-of war across the balance point make modeling even the day-to-day outcome pretty much chaotic. In other words, the closer we are to the boundary between ice and no-ice, the harder it becomes to know in advance on which side of it we are going to end up at the end of the season. [aside - maybe this could be part of the reason that the ECMWF and GFS medium range models have been doing so poorly this year] Neven's list of prerequisites looks as good as any to me - but I'm a rank amateur. Even to a professional the last straw might come from somewhere unexpected. If I was being Machiavellian I might add something to reduce the previous winter freeze - e.g. have the previous season end with very low volume but high area, and extent higher still, with much open water scattered throughout the whole arctic.Start the winter with a big storm to get the surface salinity up, then a dead calm + short deep freeze to get a skin of salty ice on the surface, quickly followed by a couple of feet or so of dry powder to insulate the water underneath. On the tail end of the next melt I'd want a just what Neven suggests - another big storm - something to stir in as much sub-arctic and deep water as possible.
Toggle Commented Aug 4, 2014 on Poof, it's gone at Arctic Sea Ice
@Chris Reynolds ... "HYCOM is intended for shipping isn't it? So do those running it intend it to be high biassed in terms of thickness to stop ice breakers running into 'briar patches' of ice too thick for them to handle. Just a WAG." ... Likewise PIOMAS? - isn't that all about not denting the conning tower when busting up through the ice to launch the missiles? Suspect the HGTG reference is lost on many these days, BTW - but not me - Here's another... "R17 is not a fixed velocity, but it is clearly far too fast."
Toggle Commented Apr 12, 2014 on PIOMAS April 2014 at Arctic Sea Ice
I followed neven's suggestion & compared the ice north of Greenland on 08/23/2012 & 08/24/2013. I had to rotate the 2012 pic because the projection on worldview has changed: http://thingsiknowidontknow.tumblr.com/ To my untutored eye, right now it looks structurally much worse than last year, but with a layer of snow on top.
Toggle Commented Aug 26, 2013 on Hole at Arctic Sea Ice
Let's hope the Earth isn't of a mind with Hamlet: "O, that this too too solid flesh would melt Thaw and resolve itself into a dew!"
Isn't the air temp always depressed in the vicinity of rapidly melting ice? That's certainly been my experience jogging (well, ok, walking briskly) around Lake Calhoun every spring. Is it too simplistic to observe that adding more energy doesn't raise the temp much above freezing as long as there is still unmelted ice?
Toggle Commented Jul 6, 2013 on So, how slow was this start? at Arctic Sea Ice
3.2 Mkm2. Based on observing the slope of the decrease in area toward the end of June, + the minimum for the year, compared with the same observations for the previous year, going back to 1995 or so. The slope on this day hasn't been steeper than now for at least ten years. IMO it's more likely to steepen further than shallow for the next month. I'd regard myself as a 1.5 (I'd have said 1.0 had I not been living in MN watching lake ice melt every spring for the past 20 years) I know the melt started slow - but IMO it's on a trend to catch up and surpass 2012.
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Jun 28, 2013