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Tommi Kyntola
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I'll stick to my earlier 1.8. It's a guestimate based on the information both in comments and linked to in here. I believe the ice is in a worse condition than the graphs and models presently show, both extent and piomas. In that sense I dont think it has been a slow start in general and I see no reason why we'd finnish higher than last year barring unexpected weather for remainder of the melt.
1.34Mkm^2, open pole and open nw passage I base that guess on enhanced feedbacks, poor state of ice, lack of MYI from last year, currents and some further wearher events.
Dave C, how do you get "min similar to 2012"? Smaller melt? If so, why? Because the freeze doesn't seem to amount to that much higher this year. I'm only curious as my guess would be the exact opposite (even bigger melt) based on little more than a hunch from this fractured freeze and just continuation of recent years.
Toggle Commented Jan 26, 2013 on PIOMAS January 2013 at Arctic Sea Ice
Nice one Wipneus. The gompertz tail comes out as expected. That's the inaccuracy I'm referring to. Now, I know some people except that to happen for physical reasons and model simulations. Be that as it may, in this particular case that comes out for the wrong reasons. In your grid graph the cells are not connected. Thus any future feedback of albedo change as a result of ice loss does not affect anything outside its own cell. Also ice transport is not there either. The ice thickness stays relatively constant in those areas through which it's transported elsewhere to melt. Hence those regions right now not yet melting, or through which ice of constant thickness passes, will produce a fit that predict a longer life time than it should based on this data. Of course it worth a note to realize that all negative future feedbacks are not at play either, but I think we all agree that right now the positives reign supreme. Another way of looking at it would be to consider a similar graph done two or more years ago. The tail would extend out earlier. And again because the positive feedback during those two or more years would not be there in the data affecting the fit or extrapolation. Or what if not such a large part of melt had taken place in thinning and lost MYI, i.e. what if all of the melt only took place at the ice edges? The grid graph would produce silly results in that case. Now, like I said, the Gompertz tail has some physical backing, too, Some negative feed-backs and Greenland winds sustaining it a little longer, iirc. The explanations I've heard have been unconvincing, but whether they turn out to be true or not remains to be seen. I can't help but think that some of the academic models have somewhat analogous problems, i.e. underestimated heat and ice transfer mechanisms. (Disclaimer, an absolute climate amateur here, I may be wrong on some or all accounts, so feel free to teach me. Also as I've lived all my life north of 60N, I've seen my share of spring and summer ice melts. The Baltic sea and lakes are naturally different beasts, but they make me susceptible to being biased for an ever faster melt towards the very end.)
Toggle Commented Jan 26, 2013 on New PIOMAS vid at Arctic Sea Ice
SATire: I don't think the Wipneus grid graph can be used to make such lengthy predictions. As I understood how it was done, it's accurate in showing what melts next, but beyond that it goes astray. It doesn't transport ice and it doesn't take into account non-local feed-backs, most notably the albedo change as there's no heat transfer either. Those areas still frozen and not quite yet next to open ocean have hardly any indication of that in their history and thus cannot accurately predict their demise on their own. It's a great chart for sure, but in my opinion one should be cautious with it. The overall PIOMAS data and the monthly averages show clearly how the individual grid extrapolation is likely to be inaccurate after a year or two. It might be interesting to plot the average of the grid approach into the overall graph and see how it fares.
Toggle Commented Jan 25, 2013 on New PIOMAS vid at Arctic Sea Ice
Wipneus, awesome graph, but few questions. Did I get it right that you've fitted an exponential decay for each cell separately and independently? If so, isn't that likely to underestimate the melt because the positive feedbacks from molten regions don't get fed back onto those still frozen? Sorry if I've misunderstood it somehow, I just started wondering because (judging with an eyechromometer) it looked like a slower melt than what the typical piomas exponential fits have been.
Toggle Commented Jan 16, 2013 on PIOMAS January 2013 at Arctic Sea Ice
Could someone explain the rationale behind the gompertz curve? Why would the last remaining blobs of ice have trouble melting? With all the major feedbacks being positive I cannot see but acceleration in the melt right down to the zero area/extent point.
Toggle Commented Oct 3, 2012 on PIOMAS October 2012 (minimum) at Arctic Sea Ice
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