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John Christensen
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Hi Jim, I believe both ARC ice images are incorrect, but the new DMI ice thickness chart seems to be more accurate, where both Kara and coastal areas of Beaufort are cleared: http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/
Toggle Commented Jul 15, 2016 on 2016 melting momentum, part 3 at Arctic Sea Ice
Agreed on that last part wayne, it does seem odd that NASA can be at one extreme, and so far from the Met Office..
Toggle Commented Jul 14, 2016 on 2016 melting momentum, part 3 at Arctic Sea Ice
Rob, It seems you are getting stuck on this point, so I have dug out the exchange with wayne from June 14th: First from me: "I read your blog wayne, seems dramatic: "Make no mistakes in judgement, this is the greatest melt in history." How would you define "greatest melt" in terms of quantity and time period?" Then the reply from wayne: "John Sea ice extent is the trickiest geophysical feature to predict, because it can be severely compacted or scattered. Volume should be easier but Piomas has a great deal of trouble with it. I made it easier for myself: "The potential for the North Pole to be sea ice free at Minima coming mid September has never been higher. Arctic sea ice extent will be smaller than all time lowest record of 2012." Written 2 months ago: http://eh2r.blogspot.ca/2016/04/2016-annual-spring-projection-made-by.html I find General Circulation Predictions a walk in the park compared to the very complex nature of not so simple sea ice."
Toggle Commented Jul 14, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
A factor often not being considered is the other expansive Arctic ice area - the Greenland ice sheet. Under the conditions in 2012, very high temperatures were created at altitude on the ice dome, which also caused extreme fohn being created, whenever some of this heated air was moved down from the dome towards sea level and the remaining sea ice. This year, temperatures in Greenland have been average and even below average in some areas after a warm spring, and higher than average precipitation has caused the accumulated mass balance to be above the 1990-2013 average: http://polarportal.dk/en/groenlands-indlandsis/nbsp/isens-overflade/ It seems to me therefore that Greenland is one of the factors required to create record-level arctic sea ice melting, and the Greenland weather this year is not contributing significantly.
Toggle Commented Jul 13, 2016 on 2016 melting momentum, part 3 at Arctic Sea Ice
That's a great update, thanks Neven! With 5.2, Dr. Schroder is now on par with NASA, which until recently was at the high end of Sept average extent predictions. It seems to confirm what I also said recently that top-3 for Sept minimum extent average is becoming less probable.
Toggle Commented Jul 12, 2016 on 2016 melting momentum, part 3 at Arctic Sea Ice
"AO can be negative and there can be a huge Low over the Arctic Ocean. AO doesn't explain anything, it is a computer model value dedicated to the positioning of the jet stream." wayne, I do not disagree with you, but: 1) Positive AO index increases the chance of a low being centered in the CAB 2) Serreze and Barrett (2008) showed that the prevalence of cyclonic activity in the CAB in June/July decreases the risk of low Sept ice extent.
Toggle Commented Jul 12, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Hi Rob, I can't find the comments right now, but I believe wayne predicted the greatest melt in history in terms of extent and volume by Sept, and secondly I do not believe wayne has withdrawn or modified this prediction at this point. I think wayne has a preference for making predictions early in the melt season compared to us wimps, who make predictions in June, when a considerable degree of events have already passed, so I do not see how a comment related to his current prediction would be inappropriate, as I specifically refer to the events taking place after his prediction was made. So I think you are overreacting a bit: The game of measuring predictions against unfolding events must be part of the game - or predictions could be made at no cost and would be less fun.. ;-)
Toggle Commented Jul 12, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
"It looks like the entire pack will be rubble before very long" wayne, I don't think so; the forecast a few days ago had us headed for AO index around -1, but now it has flipped to around AO 1 a couple of days from now. With that, the ecmwf forecast shows the low strengthening and doing a counter-clockwise trip from the Siberian side across to Beaufort and the CAA. The greatest melt in history isn't performing too well right now after also lackluster results in June.
Toggle Commented Jul 11, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Thank you for another great update Neven! D; "but the heat in the Arctic seas will eventually come into play" Yes, but right now the temperature of the Arctic seas is rather blend: Colder than surrounding land and warmer than the ice-covered areas. The warm open water areas will be able to cause some cyclonic weather only by Oct/Nov, when the land and ice have both cooled down again.
Toggle Commented Jul 7, 2016 on PIOMAS July 2016 at Arctic Sea Ice
"seems like the lowest June volume decline since at least 2010" Sorry, let me make that second lowest June volume decline since 2010, as June 2014 was lower.
Toggle Commented Jul 6, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Thanks Cato, and yes: "Waiting for PIOMAS to confirm or contradict DMI's version" So new PIOMAS data just got released. I have not downloaded the detailed set, but seems like the lowest June volume decline since at least 2010..
Toggle Commented Jul 6, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
"will make it difficult for 2016 to reach top-3 in minimum extent by Sept" - And that is just me saying that, staying somewhat optimistic due to the blend forecast; neither fish nor bird, as I believe it was once labeled.. ;-)
Toggle Commented Jul 4, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Hi viddaloo, As you saw from I believe Neven's first biweekly update, this year we have thin ice in peripheral seas and the (relatively) thicker ice in the Central Arctic Ocean, the CAB. Therefore, it was to be expected for extent to decline fast in May and June, irrespective of the lows in the CAB. However, as you see below (Click the 'Thickness and Volume' link), volume retreat has been restrained in June, and we are now at the 2004-13 average volume, according to DMI: http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/ The June weather and restrained volume decline will make it difficult for 2016 to reach top-3 in minimum extent by Sept, but again weather can still change things to some degree.
Toggle Commented Jul 4, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
"So right now in terms of solar input of energy we are what should be another Maunder Minimum. We are in solar terms at least a mini ice age" Easy does it. The Maunder Minimum lasted about seventy years - it was the duration that made it exceptional. It will therefore take a good while, before we could claim to have entered a period similar to that..
Toggle Commented Jul 4, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Hi Rob, SIPN June report; Yes, interesting report, and amazing that the MetOffice forecasts 3.6 while NASA has 5.2 - someone need to revisit their factors and weights, maybe both.. ;-) For ice concentration: Andrew Slater has created a new site, where you can compare ice concentration for a given date for different years: http://cires1.colorado.edu/~aslater/ICEDIFF/ When comparing against most years, the ice concentration level of the central pack seems to be doing quite well, while we this year have lower concentrations in peripheral seas. And, "Nobody said that NH snow cover is the "only" variable" Agreed; I should have been more clear. My point was that the spring snow cover probably correlates better with other variables (temperature, SLP) than with the decline in ice extent in June/July.
Toggle Commented Jul 1, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Sorry; I did not mean to challenge if one 'record' was more significant than the other 'record' regarding snow cover decline. And yes,Rutgers provide a good comparison, and I will need to agree it is difficult to tell how the years of 2012, '13, '15, and '16 would turn out so different just based on the NH snow cover. It may just come back to my favorite, the Arctic Oscillation, in that when the AO is in the positive phase, there is an increased chance of cyclones to develop in the CAB, but it may need a 'spark' in the form of random weather/circulation - the butterfly effect as Edward Lorenz would say.
Toggle Commented Jun 30, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
Thank you for another great update Neven! I only have one item to question, which is: "2016 still has many aspects going for it, .. and snow cover that vanished at record speed" Remember that NH snow cover vanished in the spring of 2013 at record speed, as A. Slater remarked: "From late-April to June 2013, snow cover extent retreated dramatically. On occasion during May, extent was the third lowest of all years on record. The image below summarizes the maximum retreat in snow cover extent to have occurred for a 30, 45 and 60 day period for each of the past 46 years. 2013 showed the largest retreat of all years for these three periods of time." http://cires1.colorado.edu/~aslater/NH_SNOW/ Serreze and Barrett, again from your great entry 'on persistent cyclones', on the relationship between land and sea surface temperatures and cyclones: "A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean. This pattern is associated with the influx of lows generated over the Eurasian continent and cyclogenesis over the Arctic Ocean itself. Its seasonal onset is linked to the following: an eastward shift in the Urals trough, migration of the 500-hPa vortex core to near the pole, and development of a separate region of high-latitude baroclinicity. The latter two features are consistent with differential atmospheric heating between the Arctic Ocean and snow-free land." And again from Serreze and Barrett: "..the summer cyclone pattern owes its existence to differential atmospheric heating between the Arctic Ocean and snowfree land." I would therefore argue that there may be a connection between the rapid snow cover retreat and the onset of cyclones seen in the CAB in June; the rapid snow cover decline basically alters the Arctic weather patterns to favor creation of cyclones in the CAB. It would then also seem reasonable to argue that the retreat in NH snow allows land temperatures to rise more than SST over the sea ice, so that the difference in atmospheric heating is increasing and therefore allowing summer cyclones to become more prevalent.
Toggle Commented Jun 30, 2016 on ASI 2016 update 3: crunch time at Arctic Sea Ice
When comparing ice concentration of 2016 against 2015, it appears that the central Arctic Ocean and Chuckchi has a higher concentration this year, while peripheral seas have low concentrations: southern Kara, Barents, Greenland Sea, Baffin, and somewhat lesser degree in Hudson Bay: http://cires1.colorado.edu/~aslater/ICEDIFF/ As I mentioned earlier, since the Sept min ice extent will mainly cover central parts of the CAB, it seems the extent should not drop too far, also given current weather conditions and medium term forecast. I will therefore upgrade my min sea ice extent prediction from 3.75-4.00 to 4.25-4.50 in the next poll.
Toggle Commented Jun 29, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
I had not pulled this yet, thanks for sharing Cato! Amazing how the situation has stabilized; it seems like moisture will keep pushing up across Greenland from Denmark Strait, continuing above-normal precipitation and accumulation there.
Toggle Commented Jun 28, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
Yes, also the AO index forecast is showing no significant change over the next 7 days (Has 89.9% correlation with observations): http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif
Toggle Commented Jun 28, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
Agreed, Cato, but let me add that also Greenland - after an early start to the melting season by late April - is seeing higher than average cloudiness and precipitation combined with average temperatures in June. This results in accumulated surface mass balance (SMB) currently being significantly above 2012 and also above the 1990-2013 mean: http://polarportal.dk/en/groenlands-indlandsis/nbsp/isens-overflade/
Toggle Commented Jun 28, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
wayne, you wrote on June 13th: "But by no means gone for good. In fact I expected it, with especially the opening of CAA coast, a High should settle off Gyre centre in particular near the Pole." And you mentioned this was already in the forecast. Your point was that the low was not a 'normal' low, but rather a short-lived low caused by the numerous leads and that once the water vapor had evaporated a high near the Pole would appear. How is your forecast holding up two weeks later? It seems like this did not happen,
Toggle Commented Jun 28, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
Nice graphic showing the NH polar jet 'following the sun' - moving north in summer and south in winter: http://www.classzone.com/books/earth_science/terc/content/investigations/es1908/es1908page04.cfm
Toggle Commented Jun 27, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
Rob, you said: " I've not seen any scientific paper that links the AO to Arctic sea ice decline" You should read this: The Summer Cyclone Maximum over the Central Arctic Ocean Mark C. Serreze and Andrew P. Barrett, 2008, Journal of Climate Which states: "Variability in the strength of the cyclone pattern can be broadly linked to the phase of the summer northern annular mode" - This is the AO. And this: Dramatic interannual changes of perennial Arctic sea ice linked to abnormal summer storm activity James A. Screen, Ian Simmonds and Kevin Keay, 2011, Journal of Geophysical Research Which states: "In particular, fewer cyclones over the central Arctic Ocean during the months of May, June, and July appear to favor a low sea ice area at the end of the melt season. Years with large losses of sea ice are characterized by abnormal cyclone distributions and tracks: they lack the normal maximum in cyclone activity over the central Arctic Ocean, and cyclones that track from Eurasia into the central Arctic are largely absent." The NH polar jet is typically placed near 60N, but with positive AO the polar jet can move into the range of 60-70N, with temperatures normally being somewhat lower on the northern side of the polar jet compared to south of the jet stream. If the polar jet moves north of the Hudson Strait, Foxe Basin, or Ungava Bay, temperatures in these areas will increase, accelerating the local sea ice melt. Therefore, while positive AO generally is causing higher than normal Sept sea ice extent, there could be in May-June higher than normal melting activity in areas south of the polar jet. In 2013, ice extent dropped significantly in the last 7-10 days of June, possibly related to high temperatures in southerly Arctic areas. See the "Second storm" 2013 entry for some of those temperature examples in July 2013, and where the general opinion on the thread was still not sold on the concept that the storm/low would indeed be beneficial to the overall sea ice cover. Luckily, by July 2013, the sea ice was largely gone in areas impacted by higher temperatures..
Toggle Commented Jun 27, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
NP Rob, it could also be argued that due to northward movement of the jet stream caused by positive AO, remaining ice of peripheral seas would be under increased stress.. Let's see what happens
Toggle Commented Jun 25, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice