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John Christensen
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"This slower refreeze characteristic" Sarat, please share where you find evidence of slower refreeze this year. In addition to SIE, also SIA is going up significantly (E.g. ROOS:http://arctic-roos.org/observations/ice-area-and-extent-in-arctic ), and probably also PIOMAS, if DMI volume can be at least an indicator of direction.
Toggle Commented 2 hours ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
But back to my favorite topic; AO and seasonal outlook - from 30,000 feet and all limitations considered: The AO index has been in a positive phase nearly uninterrupted since mid-June, and as a consequence the radiative heat reaching the larger NH has been slightly reduced: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml This may have helped air temperatures in 80-90N to move down at a respectable pace, though assisted also by a well-positioned low extracting cold air masses from north-eastern CAA and northern Greenland. What is also interesting is that the AO index is now forecasted to turn negative. As we have passed equinox, this means somewhat enhanced radiative heat loss in the NH. It will be interesting to follow the possible combined effect of summer positive AO followed by negative AO in the fall - if that indeed comes to pass, but overall should create more favorable conditions for sea ice than seen in the first half of the year.
Toggle Commented 15 hours ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
Yes, wayne, I am not disagreeing on the limitations of the models; each have its own area of weakness and therefore limitation needed when interpreting outcomes.
Toggle Commented 15 hours ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
wayne, Regarding freezing right now, I would think surface temperatures below -8C in areas where melting happened only by the late August storms would be sufficient to refreeze the surface layer, as the salt content must be somewhat reduced. As contrast, in Beaufort we need -11C for sea ice to form due to extended mixing over the past few months. If you look at the DMI forecast model and select 'Ice temperature', the model should show 'skin' temperature and not the 2m air temperature, where you see extend of this lower temperature: http://ocean.dmi.dk/anim/index.uk.php
"Just how is this volume increase calculated when there is vast expansion of sea ice in well above warmer temperatures?" As certain as the dawn of day, I expected you would question the PIOMAS data of ice growth in September. As certain as the questioning of sea ice concentration, sea ice area, and sea ice extent. Behold I say, a good week from now, PIOMAS will provide new data showing that sea ice has grown also this September as every other September on record, and then you can question that as well.
Agreed navegante, Sea ice volume increase in the first two weeks following the volume minimum has been 300-400km3 in the past four years, which happens in the central parts of the pack, where late season melting can refreeze under slightly higher temperatures due to reduced salt content. Initial 2-week volume increase for past years in comparison (km3): 2012 - 393 2013 - 365 2014 - 382 2015 - 317
Toggle Commented 2 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
The compactness charts that Wipneus compiles, based on NSIDC, Jaxa, or Uni Bremen data all have very low or record low compactness in 2012 in August and September, only rivaled by 2016, and around Sept. 9-13 compactness was equal for the two years.
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
At the 2016 SIE minimum on Sept. 10, with compactness equal to 2012, there was 650,000km2 more ice.
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
wayne, As you see from wipneus' great compactness graph the late season cyclones really broke down the remaining ice this year, causing compactness to get lower than 2012 during the last week of August and first week of September: https://sites.google.com/site/arctischepinguin/_/rsrc/1441086658056/home/amsr2/grf/amsr2-compact-compare.png Around 2016 SIE Sept. minimum, 2012 and 2016 shared the lowest level of compactness and for the past couple of weeks 2016 has been lower than 2012 again. So with the very low compactness of 2012, how is that 'very compact'?? And the lower compactness in 2016 for the past couple of weeks still cannot remove the extra ice, as area is higher as well, and the volume..
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
And the NSIDC Sept. average SIE in all likelihood will be in the 4.25-4.5 range, probably very close to Rob's prediction.
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
wayne, You cannot explain away the fact that 2016 has more sea ice than 2012, and that melting this year was less than in 2012. I did not calculate for this year, but compactness in Sept. 2012 was very low, as you see from Neven's update on CAPIE back then: "As you can see, 2012 is lowest of all years since 2005. This means that the pack is more spread out than in those years (also explaining the rapid climbing of IJIS extent number we're seeing in the past couple of days). Imagine what would have happened with compacting winds, like were seen in 2007 (light blue line). SIE and SIA would probably have been even lower." http://neven1.typepad.com/blog/2012/09/asi-2012-update-11-end-or-beginning.html#more With more ice volume higher extent, and higher sea ice area, there is just more ice..
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
From NSIDC charctic.. http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
Having passed the 2012 minimum SIE date, we now have comparable SIE reduction rates e.g. from June 1st to minimum: 2012 summer SIE loss: 12.36 to 3.39 = 8.97 (72.6%) 2016 summer SIE loss: 11.15 to 4.14 = 7.01 (62.9%)
Toggle Commented 5 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
NP viddaloo, and happy it worked out with the shoe string and nice clip! viddaloo/NeilT, If the DMI Forecast model is to be trusted, it seems like cold air will be moving north out of Greenland/NE CAA, which is cold enough for actual freezing: http://ocean.dmi.dk/anim/index.uk.php Then warmer air should move east from Beaufort, which probably will make DMI 80N spike upwards again. The positive spin on this current storm is probably that it helps slow/stop the Gyre..
Toggle Commented 6 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
viddaloo said: "but the CAB did NOT refreeze over the past week (see my graph above)" viddaloo; your graph shows the CAB SIA, which can go up or down although some areas have started freezing. You will see in the PIOMAS update that volume has started increasing.
Toggle Commented 6 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
"Key will be how long it takes to get back into freeze" What do you mean NeilT? - freezing temps have been spreading for weeks, at points into -10/-15C, and area and extent numbers have increased for the past two weeks also. PIOMAS volume minimum in recent years has been between Sept. 2-9 and I would be surprised if this year turns out to be any different.
Toggle Commented 6 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
On the biblical "Great Flood" and flooding to come: Humanity is not entirely unfamiliar with worldwide flooding events, and I am certain that one or more of the great meltwater pulses from the last deglaciation was the trigger for the "Great Flood" story. The main pulses were: 1. 13.5 m rise over 290 years (12,200BC) 2. 7.5 m rise over 160 years (9,000BC) 3. 6.5 m rise in less than 140 years (6,000BC). In comparison melting of the entire Greenland ice sheet would produce another 7.2 m rise. The main difference between past and present is our dependencies on concrete structures and infrastructure, so that future flooding will have a considerably higher impact than past flooding. But we are getting off topic here.
Toggle Commented 6 days ago on ASI 2016 update 7: minimum time at Arctic Sea Ice
Gerald, Not that it would be necessary to defend Neven, but consider that you yourself decided to acquire the technological device enabling you to contribute on this blog. The fact that we all can and do contribute to these blogs with devices manufactured from metals, compounds and materials mined and fabricated across the planet, together with the myriad of similar decisions made by billions of people every day is exactly what brought us to this day. So here it is: Are you willing to switch off, not just tonight, but for the rest of your life? Get yourself to a natural state of consumptive equilibrium with your natural environment? If you are not, then your only hope is the gradual adjustment that I think deep down most of us are hoping for, as naïve as it may seem.
Toggle Commented Sep 19, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
wayne, I am happy we agree that SIA is calculated based on ice concentration for grids of at least 15% ice concentration. Then I clearly misunderstood your comment from Sept. 10th where you said "measured by 15% extent or area rule, can have up to 850,000 km2 of open water" to mean that you had a concern about sea ice area numbers being inflated by this rule. It was probably the 'area rule' that sent me in the wrong direction..
Toggle Commented Sep 19, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Agreed Jim; this is a stellar example of the sea ice area declining, probably both due to concentration going down due to the storm, as well as perhaps some melt ponds being created between Svalbard and the Pole. The SIE calculation will not capture this development, causing SIE to go up, while SIA is going down.
Toggle Commented Sep 17, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Amazing that we have another cyclone in the CAB..
Toggle Commented Sep 16, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Ah yes, I missed this comment by wayne on Sep. 10th, clearly attempting to ridicule a remark on sea ice area by repeating the misstatement about sea ice area calculation: "Science? Let us see If you ignore that out of 1 million km2 of 100% sea ice allegedly measured by 15% extent or area rule, can have up to 850,000 km2 of open water, if you ignore your own eyes and mind about what dispersed sea ice would look like if it was all compacted like during a compacted year, anything can be led to speculation, sure sounds like precluded science with emotions overtaking facts." http://neven1.typepad.com/blog/2016/09/piomas-september-2016.html Unless made out of pure ignorance, these repeated erroneous remarks appear to serve to obstruct a constructive discussion based on available sea ice area, extent, and volume metrics, which is a shame and unnecessary.
Toggle Commented Sep 16, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Good luck with the interview viddaloo!
Toggle Commented Sep 16, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Hi wayne, Rob, and viddaloo, I am referring to statements like these on this blog: On August 28, wayne said: “Thanks Jim, area has the same pitfalls as extent with the 15% per grid. Did you ever wonder why? How about compensating by using 1 km grids or up to capacity of the equipment?” http://neven1.typepad.com/blog/2016/08/asi-2016-update-6-hell-and-high-pressure.html And on September 1st: “Do most sea ice prediction models depend on PIOMAS volume? If so does PIOMAS regard 15% threshold for sea ice extent or area as acceptable for 100% sea ice coverage?” http://neven1.typepad.com/blog/2016/08/2016-mega-dipole.html And on September 3rd: “I don't know if PIOMAS model uses the 15% inane rule as for extent or area. Imagine if it does, say one grid has 16% sea ice considered as 100%, how much of a miscalculation of volume is that?” http://neven1.typepad.com/blog/2016/08/2016-mega-dipole.html The misstatement is that e.g. 16% of sea ice would be considered as 100% in the SIA calculations. As we all know (You too wayne?) two grids with sea ice concentration of 10% and 16% respectively in a 4x4km grid would give this difference in calculations: SIE: (4 x 4 x 0.00) + (4 x 4 x 1,00) = 16km2 SIA: (4 x 4 x 0.00) + (4 x 4 x 0.16) = 2.56km2 The repeated reference of the 15% rule providing highly questionable numbers for both for SIE and SIA models is not correct.
Toggle Commented Sep 16, 2016 on ASI 2016 update 7: minimum time at Arctic Sea Ice
Hi NeilT, Sorry; I had moved to a different thread, so did not read this - indeed it seems like you had your neck out early in the season with these comments, I'm impressed. I stayed quite pessimistic until I saw the AO index moving towards positive and the ecmwf forecast showing the potential of cyclonic pattern in the CAB, first week of June I believe..
Toggle Commented Sep 16, 2016 on 2016 Arctic cyclone, update 1 at Arctic Sea Ice