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Neven
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Let me first make clear that I'm not saying that I think that an exponential or linear extrapolation of PIOMAS volume data is correct and that the Arctic will be ice-free for all practical purposes by 2022. There will indeed be a refuge of ice that might be hard to melt. What I'm taking issue with here, is your statement: If the PIOMAS were reliable, it should produce a regression similar to that of the Area, which I consider Area to be the most reliable metric. If one long-term metric goes down much faster than the other, as is the case with volume vs area, by definition regressions or extrapolations cannot be equal. It also doesn't mean that one is better than the other. Just as the Arctic might not go sea ice-free by 2022, it will highly likely not melt out 'several decades' from now either. And no, average thickness doesn't imply a longer regression period either. Just look at 2012, lowest volume and area/extent minimum on record, but average thickness was similar to other years. You could have just one slab of 100 km2 left, but if its volume is 0.15 km3, that means it's 1.5 metres thick, which would be 0.5 m thicker than the lowest years on the chart. So, I don't find that a good argument for saying that PIOMAS is unreliable. It may be unreliable, but not for the reasons you state.
Toggle Commented May 19, 2017 on PIOMAS May 2017 at Arctic Sea Ice
Wade, can you calculate for me the difference in volume and area between a floe that measures 10 km by 10 km and is 1 metre thick, and a floe that measures 10 km by 10 km and is 10 centimetres thick? My calculator says 100 km2 and 0.1 km3 for floe 1 and 100 km2 and 0.01 km3 for floe 2. So, area stays the same, but volume differs by one order of magnitude. Does that perhaps explain the difference in regression? Or, as Peter Wadhams said 10 years ago: "In the end, it will just melt away quite suddenly."
Toggle Commented May 19, 2017 on PIOMAS May 2017 at Arctic Sea Ice
I plan to find out what happened in 2010 and come up with a theory./blockquote> Check out the Dosbat blog. Chris Reynolds wrote at length about 2010 wrt PIOMAS.
Toggle Commented May 6, 2017 on PIOMAS May 2017 at Arctic Sea Ice
Wade, could you stay somewhat on-topic (PIOMAS and conditions in the Arctic right now) or else go to the Arctic Sea Ice Forum?
Toggle Commented May 5, 2017 on PIOMAS May 2017 at Arctic Sea Ice
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Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center: It's no surprise 2017 is still lowest on record, according to the PIOMAS model. If during the last... Continue reading
Posted May 4, 2017 at Arctic Sea Ice
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Elisee, first of all, your brush is too broad. This isn't some homogeneous organisation where image can be controlled through hierarchical systems of decision-making. Even though they are bound by a shared concern about the potential consequences of Arctic sea ice loss (and AGW in general), the visitors of this blog and the Arctic Sea Ice Forum are as diverse as can be. Some are alarmist, others are conservative, and so on. Secondly, climate risk deniers who are only interested in deceiving their fellow human beings, will always be able to find some exaggerated quote by some guy. I mean, over 10 years ago some ex-scientist said that there would come a time when British children will never see snow again. This meme is trotted out every winter, and projected onto the entire scientific community and the IPCC. If we are going to worry about that, we might as well stop talking (which is the whole idea, of course). Let them do the lying and misleading, while we each individually try to analyse and speculate about Arctic sea ice loss as honestly as we can. And let the reader judge for him/herself how trustworthy, credible, interesting it is what he/she reads on this blog and the forum. And last but not least, what you're engaging in here, is pure concern trolling. And if there's something I dislike more than climate risk denial, it's that. By your own logic you are providing fodder to climate risk deniers ("one guy tried to warn the stupid alarmist watermelons, but noooo, they wouldn't listen and announced the end of the world in every single sentence they wrote"). So don't do it again and take your concerns elsewhere. Thanks.
Toggle Commented Apr 11, 2017 on PIOMAS April 2017 at Arctic Sea Ice
When does this normally happen? This switch of HP from "icing agent" to "melting agent"? By mid April, more or less? And the melting ponds? When are they starting to form? Cato, it also depends on the latitude, of course. Melt ponds mostly start forming in May, as far as I know, but really get going in June. This also depends on melt onset, which in turn depends on downwelling longwave radiation (ie when it is cloudy). When a high pressure forms over the Beaufort Sea and stays there for a while (as suggested by current forecasts), at this time of year, it can pull ice away from the Canadian/Alaskan coasts. This open water may not freeze over again and give the melting season in that region an early boost, especially this year as it's mostly first-year ice (no MYI barrier after last year's melt). And of course, it will cause export of thicker ice through Fram Strait.
Toggle Commented Apr 7, 2017 on PIOMAS April 2017 at Arctic Sea Ice
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Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center: Just like last month, there haven't been any major changes, and that's good, because it means things haven't... Continue reading
Posted Apr 5, 2017 at Arctic Sea Ice
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But will it help? Hat-tip to Cate. Continue reading
Posted Mar 30, 2017 at Arctic Sea Ice
Yes, it's back up. It was probably Fred who crossed his fingers the right way. Speaking of milestones, this month the ASIF has broken the record of most page views in a month, and is currently at almost 1.7 million page views for March.
Toggle Commented Mar 29, 2017 on Lowest maximum on record (again) at Arctic Sea Ice
I just got behind the computer, sorry. I have notified Fred, who hosts the ASIF on a server somewhere. I'm sure he'll fix things as soon as he can. There had to be a first...
Toggle Commented Mar 29, 2017 on Lowest maximum on record (again) at Arctic Sea Ice
Over on the Arctic Sea Ice Forum I have posted an animation of the current sea ice retreat in the Kara Sea (south of Novaya Zemlya), as compared to the retreats in 2011 and 2012. The big question is whether the ice will get shoved back again, or the water re-freezes again (like happened in 2011 and 2012), or whether it will stay open this time. If it does, that will be unprecedented.
Toggle Commented Mar 22, 2017 on Lowest maximum on record (again) at Arctic Sea Ice
That's a great chart that shows the main cause of the lowest maximum on record, Jim. Thanks a lot.
Toggle Commented Mar 20, 2017 on Lowest maximum on record (again) at Arctic Sea Ice
Interesting that Bering and Okhotsk were the biggest contributors to the new record - I wouldn't have guessed that after the series of Atlantic-side lows and heat advection this winter. Indeed, iceman. I concluded it when looking at the regional graphs, particularly Wipneus' Uni Hamburg AMSR2 sea ice area overview graph. Of course, those lows also caused a kind of Beaufort Gyre-type export on the Atlantic side of the Arctic. I expect a flattish graph for the next week or two, with erratic gains in Bering, Baffin and maybe Greenland followed by a partial refreeze in Kara. I don't know about Bering and Baffin, but you may be right about Kara. The open water 'refroze' again in 2011 and 2012. It depends on the winds also.
Toggle Commented Mar 20, 2017 on Lowest maximum on record (again) at Arctic Sea Ice
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After a drop of almost 262 thousand km2 in just three days, it looks highly likely that the maximum for sea ice extent was reached two weeks ago, according to the data provided by JAXA, the Japan Aerospace Exploration Agency (via ADS-NiPR ; it used to be provided by IJIS).... Continue reading
Posted Mar 19, 2017 at Arctic Sea Ice
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Indeed, Wayne. No year since 2005 in the IJIS/JAXA data set has had a larger daily drop after a century break. A further region by region is needed, but CT is still down. I don't think Cryosphere Today will ever go up again, as the scientists involved have moved on. I wish they'd announce it officially though, so we could thank and honour them for their pioneering work in making sea ice data available to the public. As for regional graphs, there's a dedicated page on the Arctic Sea Ice Graphs website, with a collection of both MASIE and Wipneus/Uni Hamburg AMSR2 regional graphs. It's clear that extent is low mostly because of what is happening on the Pacific side of the Arctic, with Bering and Okhotsk going low. But SMOS is indicating that there is a lot of thin ice on the Atlantic side of the Arctic, and ice is already retreating in the Kara Sea (from the southwest shores of Novaya Zemlya). Given the weather forecast for the coming week, this is going to continue, and so I expect 2017 to stay low, if not lowest, on the JAXA SIE graph.
Toggle Commented Mar 18, 2017 on PIOMAS March 2017 at Arctic Sea Ice
A 112K drop even, if you are referring to JAXA, Wayne. And yes, I would call the max too, another record low on record. Very impressive. I expected it would go a bit higher, but it didn't.
Toggle Commented Mar 17, 2017 on PIOMAS March 2017 at Arctic Sea Ice
Whether the max has been reached or not, it looks highly likely that it will be a new record lowest max (JAXA SIE), third in a row to stay below 14 million km2.
Toggle Commented Mar 12, 2017 on PIOMAS March 2017 at Arctic Sea Ice
And Slater's data seems to be area-weighted, but as you correctly point out it is 925 hPa, which is too far from the surface to be indicative of ice growth during winter. I understand, but the surface and 925 hPa aren't entirely independent from each other, are they? Isn't there some correlation, or do inversions etc totally screw that up? The nice thing about the 925 hPa temps Slater used, is that it is Arctic Ocean-wide. Wouldn't that be better than just 80N?
Toggle Commented Mar 11, 2017 on PIOMAS February 2017 at Arctic Sea Ice
Andrew Slater also had an FDD graph for the whole Arctic Ocean (see here and click 'about this data'). Wouldn't that be more useful?
Toggle Commented Mar 10, 2017 on PIOMAS February 2017 at Arctic Sea Ice
The reasoning makes sense, but the question is whether those 'hot' spots are real (perhaps by comparing to previous years). Also, if you look at this sea ice drift map for December, you'll see that the ice didn't pull away from those hot spots, but rather from the Kara and Barentsz Seas.
Toggle Commented Mar 9, 2017 on PIOMAS March 2017 at Arctic Sea Ice
I may be missing something. always assumed that snow has higher albedo than ice (at least in the optical range), and that a nice thick layer of snow (think of +50 cm) delays onset of surface melting. However this thickness seems more the exception in the Arctic except for the core of the oldest ice. You may be right, navegante. In fact, according to this Wikipedia article on Albedo fresh snow has an albedo of 0.8 to 0.9, whereas ocean ice has an albedo of 0.5 to 0.7. So, I clearly have that wrong. What I meant to say, was that snow may cause an earlier melt onset because it will melt easier/faster than ice when confronted with down-welling longwave radiation (due to clouds). This will cause the albedo to go down, so that even if it re-freezes, it will be more vulnerable to melting when shortwave radiation (ie sunshine) takes over. But to tell the truth, I don't know nearly enough about these things to make definite statements. It's how I imagine things could go and why it would be a bad thing if there actually is more snow on the ice than usual..
Toggle Commented Mar 9, 2017 on PIOMAS March 2017 at Arctic Sea Ice
Thanks, Rob. I do not demand perfection from either models or satellite observations, but I wish this divergence could tell us something about the amount and distribution of snow on the ice, and then compare that to other years. A bit like we divide area by extent to get an idea of the ice pack's compactness. Or volume by extent to get an average thickness (like I do with PIJAMAS). Unfortunately, both modelled and observational data are highly uncertain (maybe the agreement up till now and the current divergence or coincidental). And then there's the differences between the PIOMAS and CryoSat-2 (AWI) grid, average vs effective sea ice thickness (as explained here), and so on. There's no way to quantify this. But maybe by comparing to ASCAT and other sources, and by making monthly SLP and SAT maps, we can get something of an idea.
Toggle Commented Mar 9, 2017 on PIOMAS March 2017 at Arctic Sea Ice
PIOMAS and DMI are not in agreement at all. DMI shows current volume in line with last year. Also OSISAF shows an 100%+ increase in volume over 2006. What's your take Neven? I'm not an expert, G man, but my experiences with the DMI volume maps are such that I don't place a lot of trust in them. I look at them occasionally, nevertheless, because every piece of information can be useful. However, there's a much more interesting divergence as we speak, and it's one between PIOMAS and CryoSat-2. That's the interesting bit I wanted to add to the blog post, which I have just published (below the monthly thickness graphs). The implications could be significant, but there's no way of telling, although I will try and have a look before the melting season starts.
Toggle Commented Mar 8, 2017 on PIOMAS March 2017 at Arctic Sea Ice
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Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center: There haven't been any major changes compared to last month, and that's good, because it means things haven't... Continue reading
Posted Mar 7, 2017 at Arctic Sea Ice
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