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Messages - Glen Koehler

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301
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:41:39 AM »
Screenshots from
"Arctic Sea Ice Score Card: Extent, Area, Concentration, Volume, & Thickness - 2019 vs. 2012"
17-page PDF at http://204.197.0.54/MEmodel/NSIDC-PIOMAS2012vs2019-July26.pdf
(but that server is misbehaving 7/27/2019, should be fixed by Monday).





2012vs2019 NSIDC concentration images

302
Some people have use for the updated regional data files:
daily:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

Dear Wipneus
Truly and thanks.  I can get the daily PIOMAS volumes by adding up the regional values from the file you post at https://sites.google.com/site/arctischepinguin/home/piomas/data

Can you also share the mid-month update for daily Thickness values?  The latest Thickness I can find on the PIOMAS site are from June 30. 

Or if not, what was the PIOMAS thickness on July 15, 2019?

Thanks much.  I have a detailed summary of 2019 vs. previous years I'd like to post that uses the latest available PIOMAS values.  I have NSIDC Extent and Area (thanks to you) up through July 26, and Volume up to July 15, but Thickness stops at June 30.

(Sorry if I am missing something blatantly obvious, wouldn't be the first time.)

303
Arctic sea ice / Re: 2019 vs 2012
« on: July 15, 2019, 06:46:19 PM »

304
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 15, 2019, 06:20:00 PM »
the conclusion seems to repeatedly be that it isn't as bad as we feared.

Whichever "we" said that, they would be wrong.  Measurements and projections of both the ASI loss trajectory and impacts have shown increase over time more often than decrease.  (This also applies to climate disruption in general.)

Check out the 16 minute "A World Without Ice" author interview Neven posted the other day at the ASIB.



305
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 15, 2019, 05:17:58 PM »
Watching the ice flow back toward the AO from the Nares also illustrates this,

AO = Arctic Oscillation atmospheric pattern, not a place.  I don't understand what AO means here.

Tealight's High Arctic analyses also use the same 7 seas. That is really useful- being able to match extent, area and volume, to AWP.

What is AWP?  It is not in the glossary.

306
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 14, 2019, 11:18:11 PM »
    IPCC is made of humans.  From what I understand the scientists (mostly unpaid for the extra work) give their best effort at corralling and summarizing vast amounts of information, then the politicians get to edit the language used to communicate it.  The IPCC reports are essential and immensely useful, imagine if we did NOT have them.  But they are imperfect. 

     Short report well worth reading --
"What Lies Beneath: The scientific understatement of climate risks"
   excerpt: 
    "What were lower-probability, higher-impact events are now becoming more likely. This is a particular concern with potential climatic “tipping points” — passing critical thresholds which result in step changes in the system — such as the polar ice sheets (and hence sea levels), and permafrost and other carbon stores, where the impacts of global warming are non-linear and difficult to model at present. Under-reporting on these issues contributes to the “failure of imagination” that is occurring today in our understanding of, and response to, climate change. If climate policymaking is to be soundly based, a reframing of scientific research within an existential risk-management framework is now urgently required. "

https://www.researchgate.net/profile/David_Spratt3/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks/links/5ad2e4120f7e9b2859343e58/What-Lies-Beneath-The-scientific-understatement-of-climate-risks.pdf

307
Arctic sea ice / Re: Glossary ... for newbies and others
« on: July 14, 2019, 04:02:22 AM »
NP North Pole

308
Arctic sea ice / Re: The 2019 melting season
« on: July 14, 2019, 03:57:33 AM »
     The "percent of melt season completed by this date" values shown by gerontocrat in the Data thread are almost certainly still applicable in 2019.  Those values include prior years when there was a lot of ice above 80N, so that's not really a new factor this year.  And the daily Extent and Area average loss curves he shows also indicate that we are just past the peak of daily melt values, and that there is a solid month of high melt potential before things start slowing down after August 16. 

    Above my skill set, but my hunch is that there opportunity for more surprises in 2019 -- perhaps another Arctic dipole, a "stuck" system with high air, reinvigorated Fram transport, GAC II, or something I can't even think of.  All bets are off with a less tethered polar jet no longer keeping things organized.

     I learn from and enjoy the speculation about the current situation and what is left to occur between now and September, and beyond.  For predictive ability it seems that the simple extrapolations of cumulative remaining melt from this date to the minimum in previous years shown by gerontocrat are as good a predictor as we have, especially now that we are about 2/3 of the way through the melt season. 
 
     ...But now I'll contradict what I just said...  The thing that spooks me about 2019 is the terrible condition of the ice and the cumulative loss of MYI.  At some point, that has to have a compelling impact on September minimum.  Maybe not this year, but my guess is that there are not many years left before the cumulative damage reaches a tipping point whereby functional changes allow a big Arctic-wide cliff from a single driving cause, or a synergism of events.

     One other factor this year is a lot more Alaskan wild fires than usual.  With the persistent torching heat in Siberia in May and June, I would guess that fire activity is increased on that side in 2019 too.  Not surprisingly (though not necessary due to the fires) the Arctic albedo in 2019 is very low this year (=higher albedo warming potential), one more factor that affect the next month of high melt potential.



https://insideclimatenews.org/news/11072019/arctic-wildfires-alaska-climate-change-heat-wave-2019-university-funding

PS -- Does anybody know why the NSIDC ASI concentration image says "No Data"? I hope the beyond-its-rated-lifetime satellite isn't blinking out.  They still have the daily extent data up to date, so I don't think that is the problem. 

309
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 13, 2019, 03:54:47 PM »
Thanks Ardeus.  Yes that is the one.  The jet stream part starts aroud 12:00.
(And thanks for doing the interview.)

 "Just Have A Think" also did a 4-part interview with Wadhams.  In part 1 he briefly discusses jet stream impact (starting at about 8:30). 

310
Arctic sea ice / Re: 2019 vs 2012
« on: July 11, 2019, 08:51:18 PM »
absotively true, but everytime I bring this up, I see eyes rolling up. People just don't want to hear about catastrophe unless it's on their doorstep...

Agreed, but it still needs to be said.  And I bet your bringing it up makes a difference to those people (like kids who don't seem like they listen  then 10 years later they remind of something you said that shows they really were hearing you all along).  https://thinkprogress.org/the-most-important-thing-you-can-do-right-now-to-fight-climate-change-according-to-science/

The AIDS campaigners pegged it - Silence is death.  Politicians have told me they'd do more on climate crisis but they just don't hear about it from constituents.  I think the tide is changing on that in U.S.   With 2020 election ramping up, climate is getting some respect for the first time.  Still only 14 minutes in first 4 hours of Dem candidate debates.  But that 14 minutes is more than TOTAL discussion of climate during all of the 2016 debates. 

Social change studies show that things don't change, and don't change, and don't change, until... seemingly in a flash, for no obvious reason, they do change very quickly.  But that slow incremental process from 1 to 2 to 3% etc. was what made it possible.  Gay marriage in the U.S. is a striking example.

Studies also show that only 10% of population needs to adopt an idea before it catches like wildfire.   While much more than 10% are already aware and concerned about climate, we need to get over the 10% hump of population ready to take on the large scale systemic change needed -- that WWII type mobilization often cited as the model for what needs to happen.  So yes, 95% may act like they aren't listening, but having it in conversation over and over is the way we get to that 10% threshold IMHO.  We gotta try. 

311
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 11, 2019, 08:18:52 PM »
BOE-year: "aaaah, blue ocean" "oh, nothing happens, it just refreezes"
BOE-year+1: "oh, again blue ocean" and we will have some weird weather, but those are just 'incidents'
BOE-year+2: "that's weird, 3rd BOE in a row and too early" and weather patterns become unpredictable in northern hemisphere with lots of extreme weather and reality finally sinks in

 :) Yup, human adaptability is huge with both good and bad consequences.

    Wipneus monthly volume chart ...
 https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png?attachauth=ANoY7crjDWOoXxuYh--3XZJMMEyECWySrgq9Q6TOUN13dC9ljMI_ZkqhIWoNNcgTFYxBjLxvMe3STZLbt3k6bd0GwBpqzGkzohemPAA3GvfzG6SssxfZyFH-g31mVYUi2ry5mVuUDXgqskqLyP-DxntNev3GJXMUYPhCqQkciQp6wMWdg2ZwozcLhLTUP5cobWGW4oqexYFgcc5c_0LIY1S59DGxmZW-Fjn61fUNUVGaZPJ2bmTzGpCSJLsnGmLbSmB9feyuhBT_&attredirects=0

    ... shows that August (and October) only trail September by about 2 years.  Since September is pretty flat on the volume curve, it doesn't seem like it would take too many years for a BOE day in September to lead to a full month September BOE.  Then, with the usual annual variations adding a few years of noise, we might have a BOE for much of August.  And that would create some serious albedo change and create a new "melting momentum" that might not be polite enough to stop by the time we notice. 

     In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.  I don't know if that is at all realistic, but if it did happen it would seem to be like Jennifer Francis thesis on steroids, with potential drastic changes in weather patterns, or just weather chaos until new patterns emerged.  I guess there's always a pattern, but if there was a complete loss of polar jet stream steering of weather systems that just seems like crazy town.

312
Arctic sea ice / Re: The 2019 melting season
« on: July 11, 2019, 07:41:03 PM »
But it seems that after Slater's death in 2016, someone else has taken over, and the Slater map has been oversimplified.  The map is now lumping together grid points with the same concentration and does NOT take into account the location of the grid points (e.g. whether they are in Hudson Bay or rather in the Central Arctic).

This was discussed last year too:
https://forum.arctic-sea-ice.net/index.php/topic,2278.msg158317.html#msg158317

Wow, if that is the case, they should pull the plug on the Slater model, or at least take his name off of it.  Failing to differentiate between Hudson Bay and CAB grid points seems like malpractice and an insult to Slater's legacy. 

313
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 11, 2019, 07:35:06 PM »
A cautionary tale
So I had a look to see if ESS area was lowest in the satellite record. It is not.
So I had a look to see in which year on this day was area lowest.
The answer?1990, 29 years ago.[/i]

Thanks for all the great number crunching gerontocrat, Juan C. Garcia, Alphabet Hotel, Killian, uniquorn, Aluminum and others. 

gerontocrat --  any insight on what caused the ESS crash in 1990?  That was a tremendous anomaly esp. for its time (oh no, I'm starting to talk like Trump).  Was there a storm, a heat wave, or did the USSR get rid of leftover nukes over the ESS?

314
Arctic sea ice / Re: The 2019 melting season
« on: July 10, 2019, 03:16:41 PM »
One question about this graph on Karsten Haustein's website.
Does this mean the GFS model is underestimating temperatures, or is it the other way around?
See chart at https://forum.arctic-sea-ice.net/index.php/topic,2591.msg212351.html#msg212351

    Non-expert talking, but I've been tracking GFS prediction vs. GISTEMP finalized values for several years.  Looking at the chart and my monthly comparisons indicates that the chart is saying that for Jan, Feb, Mar and Apr the GFS forecast turned out to be lower than the subsequent GISTEMP observations (by 0.06 C averaged across those 4 months).  For May, the GFS forecast turned out to be slightly (0.01 C) above the reported GISTEMP observation. 
   
    June forecasts were running above verification until mid-June.  On June 12 NOAA switched to new FV3-GFS model that so far has been underestimating global surface temperature when compared to verification.

      As of July 10, based on observed GISTEMP for Jan-May, and GFS forecasts for June and July 1-17, the estimate for end of year 2019 average is ca. 1.17 C above 1850-1900.  2019 will be first or second place (85% chance) relative to all other years in 1880-2019 GISTEMP record.  2019 is near record warm with only moderate El Nino effect, and on downward side of solar cycle which has a real but smaller influence.

    Bottom line: The planet continues to warm.  IPCC projections are based on straight line 30-year average projection of  0.2 (+/- 0.1) C per decade.  But a closer look shows that the rate of increase is increasing, e.g. 2009-2019 (11 years to includes a full solar cycle) change in GISTEMP is 0.36 C per decade.  We will be lucky not to pass 1.5C by 2032.  God bless the folks who AFAIK mostly donate their time to create IPCC reports.  But any report that requires consensus of 1500 scientists and 200 governments is bound to be conservative.  If you think IPCC is alarmist, read https://www.researchgate.net/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks
     

     OK, done preaching to the choir.  Not completely on topic for 2019 melting thread, but obviously related.  The energy that is melting the ASI is relentlessly increasing because of our choices.  Being aware means being alarmed, and better yet activated in pursuing solutions that are already available. 

315
Arctic sea ice / Re: 2019 vs 2012
« on: July 09, 2019, 09:55:06 PM »

From NSIDC archive of daily Arctic sea ice concentration images

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/images/2012/07_Jul/N_20120708_conc_v3.0.png
vs.
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/images/2019/07_Jul/N_20190708_conc_v3.0.png

FWIW - Some amateur opinions for consideration and feedback:
1) to my eye July 8 2019 ASI concentration looks more vulnerable than same date 2012.  The few areas where 2019 has more ice are doomed by Sept. anyway.

2) I don't think the extent and area metrics we use to compare between years fully reflect the degraded ice condition in 2019.  Volume has a better chance of reflecting actual situation, but of course it has its own issues.

3) There is still a lot of melt season weather left to go, and as reported in the forum, late July-August 2012 weather was conducive to melt.  While June 2019 was blistering, it remains to be seen what remainder of 2019 melt weather will be like, but it will be hard for 2019 to match late-season 2012.  So that's gives an edge to 2012 in terms of the Sept. minimum extent/area/volume.

4)  And 2012 had the Great Arctic Cyclone. I have to assume that an event of that impact is unlikely in 2019.  But 2019 may bring its own events -- perhaps a couple of less intense events will have cumulatively equal impact as the 2012 GAC.  A return of an Arctic dipole hinted at in the 10-12 day forecast yesterday is an example of hits 2019 could yet deliver to the weakened ice fortress.
   
 5) Of greatest importance -- 2019 includes 7 additional years of a) continued decline of anchoring multi-year sea ice, b) what appears to be qualitative functional changes in ocean heat incursion, c) increased ice pack mobility, d) polar vortex weakening, e) higher atmospheric CO2e, and f) higher global SAT -- by about 0.3C increase between 2012 to 2019.  That's a huge amount of extra energy in the surface layer of the climate system (not even counting the energy buried in the ocean, some of which could affect Arctic sea ice melting this year).  There is a lot of additional heat embedded in the Arctic and surrounding system in 2019 vs. 2012.
   
   6)  Because of #5, I think we really can't know how close to the cliff we are.  But we can be sure that we are getting closer to that cliff every subsequent year of not only persistent elevated GHG level, and not just year-on-year additions, but increases in the rate of increase of GHG loading. 
 
   7) So... 2019 vs. 2012?  A toss up for Sept minimum only because 2012 was such a blow out.  But on the current trajectory it's just a question of when, not if, cumulative progression will push the system below 2012 and make every year below 2012. 

  8) It's natural to focus on  landmarks like Sept. minimum extent/area/volume, but in case you missed it, see the 365-day running average extent the industrious and appreciated gerontocrat posted at https://forum.arctic-sea-ice.net/index.php/topic,2533.msg211770.html#msg211770.  And the even more dramatic 365-day running average volume posted at https://forum.arctic-sea-ice.net/index.php/topic,119.msg211798.html#msg211798.
     More than the ASI status on a single September day, those trends show the larger story of what we are doing to a critical part of our climate system. 

     The world needs the people informed by this forum to spread the news of this existential threat to family, friends, neighbors, colleagues, and politicians.  Please talk about it, that is the essential first step.       


316
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 04:55:15 AM »
Even if 2019 does not end up below 2012, the SIPN estimates all hovering just above 4 million km2 are historically low

Walsh, J. E., W. L. Chapman, and F. Fetterer. 2015, updated 2016. Gridded monthly sea ice extent and concentration, 1850 onwards, Version 1.1. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media. http://dx.doi.org/10.7265/N5833PZ5.

As for the horse race with 2012, am I the only one thinking that most of the SiPN estimates, with average of 4.2 km2 extent at minimum, are too high?  Possibly because they are based on historical correlations that no longer apply to a new Arctic sea ice regime where all the ice older than 2 years may be virtually extinct by the end of 2019 (except for nooks and crannies in CAA).

   Perhaps I am overreacting to latest NSIDC Arctic sea ice concentration image.  To me it looks like a pile of slush that could be flushed out through the Fram Strait with the right combination of warmth, clear skies and a couple of storms.  It does not look like an ice pack with enough resistance to withstand the remaining 45% of melt season.


317
Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 08:59:17 PM »
RE Pagphilus post #2776 on Albedo

   - At Reply #55  in "Atmospheric connections, structure, and long range weather forecasting" you can see abstracts of two recent studies on the effect of current (as 2011) and future (ice free summer Arctic Ocean in ?) albedo change from Arctic sea ice decline on global energy balance. 

318
RE post #2751 about albedo in the 2019 Melt Season thread

Radiative Heating of an Ice‐free Arctic Ocean
Kristina Pistone Ian Eisenman V. Ramanathan
First published: 20 June 2019
https://doi.org/10.1029/2019GL082914

"During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years."

Trillion tons CO2, i.e. about 25 years of current annual global emissions.  That's just a theoretical benchmark number of course, we are a long way from Arctic being ice free all summer.  But every portion thereof adds another slice of warming energy. 

Same authors did an earlier, more practical study:
Observational determination of albedo decrease caused by vanishing Arctic sea ice
Kristina Pistone, Ian Eisenman1, and V. Ramanathan
322–3326 | PNAS | March 4, 2014 | vol. 111 | no. 9
www.pnas.org/cgi/doi/10.1073/pnas.1318201111


"The decline of Arctic sea ice has been documented in over 30 y of
satellite passive microwave observations. The resulting darkening
of the Arctic and its amplification of global warming was hypothesized
almost 50 y ago but has yet to be verified with direct
observations. This study uses satellite radiation budget measurements
along with satellite microwave sea ice data to document
the Arctic-wide decrease in planetary albedo and its amplifying
effect on the warming. The analysis reveals a striking relationship
between planetary albedo and sea ice cover, quantities inferred
from two independent satellite instruments. We find that the Arctic
planetary albedo has decreased from 0.52 to 0.48 between 1979
and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar
energy input into the Arctic Ocean region since 1979. Averaged
over the globe, this albedo decrease corresponds to a forcing that
is 25% as large as that due to the change in CO2 during this period,
considerably larger than expectations from models and other less
direct recent estimates. Changes in cloudiness appear to play
a negligible role in observed Arctic darkening, thus reducing
the possibility of Arctic cloud albedo feedbacks mitigating future
Arctic warming."

Note that study period ended in 2011.  After 2019 easy to think that 25% could be up to 30%.


319
Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 12:39:02 AM »
+1 Steerpike.

   No need for arguments about the 2019 minimum, having a different opinion doesn't make you a denier.  We will all have our hunches confirmed or refuted soon enough. 

    The next 6 weeks will be interesting no matter what happens.
For those of you keeping score at home.


320
     Has anyone come up with a numerical relationship between Arctic sea ice compactness and average pack rotation speed, or amount of export out the Fram Strait? 

     I'm spooked by the idea that decades of  cumulative thinning and removal of old ice as anchors has led to a functionally new state in the CAB ice pack making it more vulnerable to wind or current driven transport. 

   During the GAC in 2012 there were comments that if the ice had been thicker the cyclone damage to the ice would have been much less, but the average thickness by then had been reduced enough to allow much more wave damage.  Since 2012 the trend towards thinner and more rotten ice has had another 7 years to make the remaining ice even more vulnerable today.  Any observations about average pack rotation 2019 vs. earlier years much appreciated. 

   Wipneus's Farm Strait export chart doesn't show increasing export trend, so my logic may be missing key factor.  And I don't know of any other measure of export loss or pack mobility.  It just seems to be rotating more this year.  If there was a correlation of mobility or transport with compactness that would at least provide a measure to track this issue and indicate I'm not making all this up in my head. 

321
Arctic sea ice / Re: The 2019 melting season
« on: June 24, 2019, 06:30:58 PM »
I don't have the experience to be convinced of my hunches.  Looking at cavitycreep's animation post #2393, makes me wonder what others think about two observations:

1.  It seems that multi-year trend towards thinning and rotten ice has reached a tipping point.  The effect being that when combined with the destructive current and near term weather forecast, the indicator measures (Extent, Area, Volume) are primed to go off a cliff in the next week, are likely to reach 2012 level even without an August cyclone, and below it if there is one.  Of course it all depends on July weather, but from what the weather gurus on this forum are saying there is no apparent weather relief for the ice in sight.  The persistence of the northern Siberia roasting for week after week is searing my memory as well as the permafrost.   

Except for nooks and crannies left in the CAA, it looks like by October 2019 the extinction of 4- and 5- year old ice could be largely complete. 

2.  Is the CAB pack rotation more mobile this year?  Wind speeds do not seem abnormal which makes me wonder if enhanced mobility of weaker, fractured ice  is another reinforcing feedback driving the 2019 melt season.  Or (if mobility is indeed higher) is the positioning of the High and Low cells and resultant wind orientation the only factor that really matters?   

322
Fish - Is there precedent for Atlantic ocean heat intrusion meeting up with Pacific side?  Any chance of that happening this year?

323
Arctic sea ice / Re: The 2019 melting season
« on: June 18, 2019, 07:34:09 PM »
RE wdmn
And how long until open water all the way around to Eastern Greenland? It's not much further off.

Newbie question - Is there modern precedence for open water all the way to Eastern Greenland?

324
RE Nanning #1886
     The guy who built and runs Climate Reanalyzier (CR) (Sean Birkel) is precise with his terminology.  While I can't be 100% certain since I have not asked him, I'm pretty sure if it was using median he would labeled it "median", not average.  So I can almost guarantee that "average" indeed is the average (mean) for both for 2M temperatures and for anomaly. 

     Furthermore, he says this in an explanatory note on multiple CR pages
"2m Temperature refers to air temperature at 2 meters above the surface. 2m Temperature Anomaly refers to the departure of the current day (or hour) forecasted temperature from a long-term mean for the same day (and hour) of the year. The anomalies here are based on a 1979-2000 reference climatology derived from the NCEP Climate Forecast System Reanalysis (CFSR). This 22-year baseline is used instead of the more common 1981-2010 climate normal because 1979-2000 represents conditions prior to rapid Arctic warming and sea-ice loss."

   Speaking of CR, note that it uses GFS, and that last week after the June 12 transition to the new version of GFS there was an issue with temperature values.   CR had a cautionary note to that effect last week, but now I can't find it, so perhaps the issue has been resolved.  But as of June 17 there is still a cautionary notice on Karsten Haustein's 2M temperature anomaly graph at http://www.karstenhaustein.com/climate.php

325
RE Lefty Larry "I will keep lurking and keep asking questions."
"I want to know more."

    While ASIF community is great and appreciated, and THE best place to watch the Arctic ice melt, there are better places to understand the big picture regarding scientific consensus and implications of the climate crisis.  Instead of having to figure it out ourselves with limited time, resources, and expertise, wouldn't it be great to convene a bunch of experts in every arena of climate, meteorology, impacts on agriculture, health, economy etc. to look into these very questions?

     Yes, it would.  And it has already been done, repeatedly, by many countries and of course, by the U.N. too (IPCC).  A great example, updated only 6 months ago in fall of 2018 is the U.S. National Climate Assessment at
https://nca2018.globalchange.gov/.  It is written from/for a U.S. perspective of course, but I sense that is your residence and thus of most immediate concern.  The report website provides nice summaries and graphics so you can quickly get to the bottom line.  You don't have to guess at what's going on. 

     People who study this stuff every day for entire careers have given their time to tell us what's going on.  Just because politicians who are ideologically blinded by fossil fuel interest and status quoism ignore blatant facts does not mean you have to be as willfully ignorant as they are.  Indeed U.S. polling shows that despite wildly successful programs to delay response to the crisis by sowing confusion and doubt, a majority of U.S. residents are coming to understand that yes humans can, and are, interfering with the climate system we depend upon for life support on spaceship Earth. 

     Or go to https://skepticalscience.com/  to find scientifically reviewed and credible responses to flawed arguments and bogus "evidence" that have been used in attempts to contradict the scientific consensus.  Read up, think about those grandkids, and decide what is the defensible reply you can give to them, and to yourself, 10 years from now when they ask you what you were doing with your political activity when the climate crisis emerged as a clear and present danger back in 2019.   

     (BTW, the denier industry used the same methods and in some cases even the same consultants as was done in fighting the tobacco smoking - cancer connection, this is not innuendo, but fact.  One of the consultant agency's motto, actually written in a memo: "Doubt is our product." )

326
RE:  LeftyLarry
1.   .... "ice comes and goes naturally and man adjusts"
2.  ..."ice been slowly declining since the end of the ice age"   
3.  ...."could a volcanic eruption, bring enough cooling to regrow the lost ice and stop the long term patterns of continued loss"
4. "If all the ice melted and the oceans rose , wouldn’t there still be a huge net gain of habitable land overall?"

    Whether trolling or not, these are questions/assumption many people have, including the U.S. Secretary of State, who recently suggested that people will just move to accomodate a change climate, that climate has always changed, etc.
    What is missing in those perspectives is a sense of scale for time and impacts, along with some basic misunderstandings.

My take on 1-4.
    1.  As others here have noted here and elswhere, it's one thing for a nomadic society of let's say 7,000 humans to move their tents inland in response to millenial rates of change.  Quite another for 7 billion humans with massive infrastructure investments and needs to react to rates of change 10x to 100x faster, thus decadal changes as large as what happend across a 1,000 years in the past. 

     2.  Others here have commented here in more detail.  I'll just add that the "natural" trend has been a gradual cooling since the Holocene peak a few thousand years ago.  Gradual because that cooling was due primarily to natural, = very slow, shift in orbital cycle.  What humans are doing to atmosphere, starting with use of coal as energy source starting ca. 1750, and esp. since 1970 with global increase in fossil fuels, is orders of magnitude more intense and faster than even the most radical climate shifts that led to mass extinctions (90+% of species) in the geologic record.

    3.  Even another Tambora eruption (which caused the "Year without a summer" in New England in 1816) won't protect us from our radical heating of the Earth.  While some climate scientists say the temperature effect is discernible longer than the usually cited 'couple of years', it is temporary nonetheless.  A cooling caused by volcanic emissions into the stratosphere, or a synthetic version through geoengineering, also does nothing to reduce ocean acidification.  Geoengineering to reduce solar energy also introduces major risk of disrupting monsoon and other weather patterns.  "Let's try this, what could go wrong?"  Lots.

    4.  Moving from recently inundated coastlines to newly exposed land formerly under ice caps would bring with it economic and humanitarian destruction of unprecedented scale in the history of human civilization since 4000 B.C.E..  But in addition, just moving the crop belts north isn't going to work.  The temperature bands will move north, but the amount of solar radiation for photosynthesis isn't changing, and the glaciated soil types in central Canada, for example, are not the same as Iowa which used to have 10 feet of top soil in places.  It's going to be tough enough to feed 10 billion people in 2050.  Doing that with degraded ag productivity, which is the consensus projection for global average temperature beyond +1.5-2C (mixed results for lower temp. change) could be impossible. 
      And don't let anybody fool you with the "CO2 fertilization" smoke screen. Increasing CO2 can indeed increase plant growth under controlled conditions where everything else is supplied at optimum (water, fertility, temperature).  Raise CO2 to 450-500ppm in the real world and you won't get any plant growth benefit because those other inputs are not optimized.  Major world food crops are near their thermal maximum now.  Increased temperatures would/will take them over the top of the curve and onto the declining production side even if water supply wasn't an issue.  Moreover, studies find that for the plants that we eat, aka "crops", while they can be grown bigger under higher CO2 with those perfect conditions I talked about above, the density for key nutrients goes down, so a person would have to consume more to get the same amount of nutritional benefit.

    Bottom line - climate disruption is going to kill people.  Lots of them.  The brown and poor people will get hit first, but nobody will escape the consequences of altering the basic life support system of planet Earth.  And by the way, we can't go to Mars.  Think about how many people on Earth it would take to support a colony of a dozen people living inside canisters on Mars.

    So if you love your grandkids (and how could you not) then do everything you can to raise awareness and alarm because this really is a crisis.  It is an unnecessary and avoidable crisis, because we already have the technical capability to produce the energy we need without suicidal continuation of fossil fuel addiction.  The real issue is one of character, long-term wisdom vs. short sighted fear, political will, and mobilization.  Start by refusing to vote for anyone who puts the lives of you, your children, and your grandchildren in mortal danger.

   Sorry for long post.  But you asked and this is the most important issue of human existence.  We have to get this right.  Failure is not an option.

327
Arctic sea ice / Re: The 2019 melting season
« on: June 14, 2019, 06:27:48 PM »
To you GFS watchers (which include Climate Reanalyzer) -- note there is a significant temperature issue with the switch to new FV3 GFS model core on Tue. June 12.  Be wary of temperature values until this gets cleared up.  I don't know if it affects other variables. :-X

328
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: June 13, 2019, 12:43:27 AM »
RE #279   Are there full season versions of this video available from past years?  Would be very interesting for comparison.  I hope we have future updates of this video, it's the best thing I've seen for representing pack rotation and export.   

     Apart from the recent high temperature weather forecasts, it seems that low extent on the Pacific side; recent rapid and accelerating deterioration along the Siberian coast; and ice condition and mobility are the three big stories so far this melting season. 

     But I also see on Wipneus chart that Fram Strait export as measured by ice Extent was at normal level for May.  So I may be overeacting to the pack motion. 

    The video in Uniquorn's post shows the Nares Strait as a nasty leak shuttling ice out of the Lincoln Sea at a rapid pace.  Since Nares opening was early this year, that makes me think that overall export is an increased source of ice loss this year, and may be disproportionately removing what little 4 and 5 year old ice was left.

 

329
     Instead of extent, area & volume, has anyone ever calculated a total Arctic Sea Ice thermal mass index?

     Such a value could incorporate all three of the current measures (E, A, V), along with an average salinity % of the ice to estimate how many megajoules of melt energy would be required to transition it all from ice to water. 

      It might also include a measure of fracturing or average floe size to represent the surface area of remaining ice.  A square meter of ice as a separate little chunk surround by ocean water has a lot more exposure to warm water (and a tiny bit more to solar energy) than a square meter of ice embedded in a solid pack. 

     Going even farther, it might be possible to add in the average transport speed relative to floe size, and use that to include an estimate of exposure to loss by export into the Fram Strait or another ice killing zone.  It seems to me that as ASI decline continues, a point will be reached where mobility will become a huge factor.  But neither E, A, or V will reflect that as it happens, only after the effect of increased mobility leading to increased export losses occurs.     

     With so many levels of estimation, the resulting index would have a large noise to signal ratio. But an attempt to include all the relevant factors into one index to rule them all would be interesting for comparison to the standard measures.  Even with internal variability, because it represents a broader range of influences, a long term trend of a thermal mass index might have lower interannual variability than E, A, or V because it accounts for factors they overlook.  And it might be a better indicator and predictor for where we are in the process of losing summer Arctic sea ice.

    The main point is that the existing metrics do not include any measure of the quality of the ice beyond thickness.  A thermal mass index would represent the fact that the ice that remains has a much higher portion of "rotten ice".  Volume by itself represents the thin vs. thick ice factor, but not the fact that thin ice not only has less volume, but has higher salinity and lower melt temperature, which in addition to structural aspects, makes it qualitatively different and less resistant to melt, i.e. has less thermal mass per unit volume. 

       So the index would be S (avg. salinity) * M (avg. mobility, due to fracturing and floe size vs. continuity of ice cover) * X (avg. exposure to melt energy through solar energy on top and ocean water on the side) = Q (qualitative measure of ice quality).  That cumulative value Q * the Volume would be the Thermal Mass Index.  Hey it's the "Stupid Question" forum, right?

330
Arctic sea ice / Re: Fram Export
« on: June 11, 2019, 04:28:26 PM »
Thanks Oren, exactly what I was looking for.  I had seen that before just couldn't remember where.
johnm33 - ice only.  Just trying see how much export is contributing to "melt" season relative to other years.

331
Arctic sea ice / Re: The 2019 melting season
« on: June 11, 2019, 02:03:51 AM »
     Just guessing, but i have to wonder if the CAB number is distorted by fractured mobile ice from peripheral seas getting pushed into the middle.  If so, then the higher CAB value is not necessarily an argument against new record low extent, area or volume this year.  In any case, it will be interesting to see status update after the heat forecast for Siberian coast over the next 10 days.  In other words, I think all bets are still on the table for 2019 melt season. 

     Again, just half-informed guessing, (but if the U.S. President can spew word salad without bothering to read, I should get a shot having at least read up on the topic  -- Don, if your listening I will pay for your subscription to the Arctic Sea Ice Forum). 

    What has me spooked about the Arctic sea ice this year in particular is that the "structural fundamentals" seem to falling apart - dramatic cumulative reduction of multi-year ice; apparent loss of the Beaufort Gyre as a nursery, and potentially it becoming a new killing zone; consistently mild (for the Arctic) winters for most of the years since 2004, and every year starting with 2014; apparently high ice mobility this year; suspicious indications that the polar cell is weakening and that weather patterns that bring warm air into the Arctic may be increasing etc.

   Thus, the threat is much broader and deeper than a temporarily warm forecast.  If I'm wrong about all or any of these, let me know.  I like to be an informed worrier. 

   (PS Slightly off topic, but the June 12-13 GFS shows potential GIS surface melt not far behind the epic July 11 and Aug. 6, 2012 blasts)

332
Arctic sea ice / Re: Fram Export
« on: June 11, 2019, 01:00:38 AM »
Maybe this belongs in "Stupid Questions", but... given the importance of Farm Strait export, there must be a daily updated graph showing estimates of how much is moving out the Arctic and into the Atlantic ice killing zones.  Any suggestions of where to see that?

333
     Stepping away from the feedback discussion (I'm still hoping for more suggestions or critques), here is an abstract I bumped into today that is entirely in sync with the thread topic.

Multiweek Prediction Skill Assessment of Arctic Sea Ice Variability in the CFSv2
Liu, Yanyun; Wang, Wanqiu; Kumar, Arun. Weather and Forecasting; Boston Vol. 33, Iss. 5,  (Oct 2018): 1453-1476. DOI:10.1175/WAF-D-18-0046.1
Publisher logo. Links to publisher website, opened in a new window.

Abstract
     "Skillful Arctic Sea ice prediction is becoming increasingly important because of its societal, industrial, and economic impacts over the polar regions and potential influence on lower-latitude weather and climate variability. In this work, we evaluate the multiweek forecast skill of Arctic sea ice using the Climate Forecast System, version 2 (CFSv2). To the authors’ knowledge, this is the first effort to diagnose and assess the skill of multiweek Arctic sea ice prediction from a coupled atmosphere-ocean model. Analysis of a suite of retrospective 45-day forecasts spanning 1999-2015 shows that CFSv2 captures general features of sea ice concentration (SIC) variability.

    Total SIC variability is dominated by interannual variability, which accounts for more than 60% of the total variance. Submonthly variability accounts for 29% of the total variance in December, 20% in March and June, and 12.5% in September. We assess the ability of CFSv2 to predict the pan-Arctic SIC, as well as regional SIC in nine Arctic regions. Results show that the SIC prediction skill is highly region dependent (e.g., higher prediction skill for Kara/Barents Seas and lower for the Canadian Archipelago). Overall, the maximum anomaly correlation coefficient (ACC) of SIC for both melt and freeze-up seasons is near the marginal zones, and their spatial distribution shows a relationship with the distribution of the variance. If the ACC of 0.5 is taken as the critical value for skillful prediction, the predictability of weekly SIC near the marginal zones is about 5-6 weeks. Prediction skill for Arctic sea ice extent is above 0.6 for the entire six target weeks and has a large contribution from interannual variability."

334
    I just read about yet another feedback mechanism I was not previously aware of:
      ' Freshly melted ice ... creates a layer of cold water that protects sea ice above from more melting.   "It isolates the ice from the hot devil water sitting at the bottom waiting to come up" Wagner explains.  Less sea ice means there will be less of that protective cold layer, leading to even more melting. '
https://www.cnn.com/2019/06/08/world/arctic-beneath-ice-intl/index.html

     Which got me thinking it would be useful to have an inventory of all the significant reinforcing ("positive") and suppressive ("negative") feedbacks that affect Arctic sea ice.

    I did not find any forum title where this would fit, but this section seems to be the most closely related topic.  It could require its own thread, similar to the Glossary.

Here is the kind of list I have in mind:

Reinforcing feedbacks:
1. Melted ice creates cold layer that insulates remaining ice from warmer subsurface water.  Less ice to melt reduces this insulating layer.  Which leads to even less insulating cold layer water.

2. Less ice leaves darker ocean water with lower albedo, thus energy from solar radiation is absorbed into water instead of reflected.  Warmer water leads to less ice.

3.  Overall, fractured ice is more mobile and thus more susceptible to being exported via Fram Strait or Nares Strait.  There is chance of an ice bridge to block export via Nares Strait with fractured, reduced ice cover.  Increased export results in less multi-year thick ice, and more mobile young ice the next year.

4.  Fractured or thin sea ice floes have more surface area per unit volume and therefore melt at lower temperatures than thicker ice, or larger ice floes.  This leads to less surviving ice the summer to become thicker multi-year ice.

5.  Fractured vs. contiguous ice allows more wave action that interferes with freezing of ice and allows wave action to break ice into smaller pieces less resistant to melt.  Resulting in more fracturing of the remaining ice and even more wave action.

6.  Albedo reduction by replacing ice with dark water leads to warmer water and more energy in the Arctic Ocean system.  That in turn increases frequency, intensity, or both, of cyclones causing wave action that break up ice. Which reduces albedo even further.

7.  Weakening of the Polar Cell results in more frequent occurrence of Arctic Dipole, that increases export of ice out of the Arctic, which lowers Arctic sea ice, which leads to warm Arctic Ocean water, which leads to further weakening of the Polar Cell.  (whew, that's a long chain)

8.  Loss of ice cover weakens the polar cell which in turn allows more incursion of of warm moist air masses from the south into the Arctic, which leads to more weakening of the polar cell.

9.  Weakening of the polar cell allows more cyclonic systems to move into the Arctic.  Those cyclones disrupt the Arctic sea ice, and in doing so further weaken the polar cell.

10.  Younger, thinner ice has higher salt content and thus lower melt temperature.  Therefore it has less chance of surviving the summer melt to become more resistant, thicker multi-year ice.

11.  Reduced snow cover allows earlier spring warm up of Arctic land mass, which results in warmer air flowing onto the Arctic Ocean. This warms the system as a whole, leading to reduced snow cover and earlier snow loss the following year. 

12.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the fall and winter.  More extensive or thicker cloud cover in fall and winter reduces heat loss thus reduces winter refreezing.

13.  Earlier spring warm up of Arctic land mass, results in increased permafrost and land ice thaw, resulting in earlier and more melt water flowing from land into the Arctic Ocean. The meltwater warms the Arctic Ocean and reduces Arctic sea ice.  Which leads to more open water with lower albedo to absorb solar radiation in the summer, increasing summer heat content of the system  More open water allows this heat to escape to moderate winter air temperatures and earlier spring warm up.

14.  Reduction of Arctic sea ice allows increased flow of warmer Pacific or Atlantic water into the Arctic, leading to further decline of Arctic sea ice, leading to more Pacification and Atlantification of the Arctic Ocean.

***
Compensatory or Suppressive feedbacks:
1.  Ice cover insulates the Arctic Ocean in winter.  With less sea ice cover there is faster energy loss and winter cooling, and thus faster winter ice increase after a lower September minimum extent.

2.  Thin ice grows much faster than thick ice.  Thus faster winter ice increase compensates for thinner ice after a strong melt season. 

3.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the summer.  More extensive or thicker cloud cover in summer reflects more solar radiation and thus reduces summer ice melt.

*****************************

     My wording is no doubt less than perfect for many of these.  Some may be just plain wrong.  Some I just made up!  Maybe I should just find a good book or review article with such a list.  Any suggestions?

   If you think a proposed feedback is incorrect or wrongly stated, it would helpful to have that noted.  But I'm not looking to start multiple debates about which feedbacks are most important. 

      I don't get a commission for each new proposed feedback, so there's no need to get heated.  The planet is hot enough as it is.  These are just suggested entries.  There must be suppressive feedbacks missing from the list.

   I just thought a list would be interesting because I keep finding out about feedbacks I had not previously been aware of. 





335
Arctic sea ice / Re: The 2019 melting season
« on: June 08, 2019, 09:50:11 PM »
Good explanation of the Arctic Dipole and its interaction with Arctic Sea Ice
https://en.wikipedia.org/wiki/Arctic_dipole_anomaly

Jeff Masters - Weather Underground - the early June Arctic forecast and prospects for summer
https://www.wunderground.com/cat6/Strong-Arctic-High-Pressure-System-Bringing-Significant-Melting-Sea-Ice

336
Arctic sea ice / Re: The 2019 melting season
« on: June 08, 2019, 07:28:45 AM »
1. RE:  Thicker snow cover on floes.
But with NH hemisphere snow cover low this year, and with snow cover north of Greenland going out earlier than "normal" (not sure what that word means anymore), then why would there be thicker snow cover this year to interfere with melt pond detection?

2.  If snow cover is interfering with melt pond detection, it seems like that situation should turn around quickly with the heat forecast for coming week.

3.  What's the typical date by which information on melt ponds is considered measured and applicable as a predictor for the remainder of the melt season?


337
Arctic sea ice / Re: The 2019 melting season
« on: June 07, 2019, 04:42:40 AM »
Thanks pccp82. 
My bad.  The image I had in mind was August 6, 2012.

I guess at that point we were discussing the Great Arctic Cyclone of 2012, and I confused that with the great GIS melt day of July 11, 2012.


Looking at that same view for dates on either side of either event, or July-Aug dates in other years, gives some perspective for how out of bounds both events were.   For example the July 21, 2018 image seems to be typical for recent dates in July-August:     

Trying to save face, I went looking for the average 2meter max temp. forecast for Greenland over the next 3, 5 and 10 days https://climatereanalyzer.org/wx/fcst_outlook/, but those are now not showing anywhere near the extent of GIS surface melt shown in the 2012 images.  Update-as of June 9, GFS forecast on Climate Reanalyer shows majority of GIS above freezing on June 13, not too far behind extensive and record breaking surface melt events on July 11 and August 6, 2012.

    While the updated hourly forecasts have no shortage of positive 2M temp anomalies for Greenland over the next 10 days, the max temp hourly forecast also indicates that the area of GIS surface melt next week won't be anywhere close to the July 11 and August 6, 2012 images.  So either I just blew it with respect to Greenland surface melt coming next week, or the 10-day outlook changed.    ***My mistake in previous post was misunderstanding that the 10-day Greenland surface temp reading was not the average for a 10-day period, but the average of hourly values for the 10th day, i.e. a single day reading not a 10-day average.  As noted above, updated forecast shows that June 13 (which was the 10th day noted in original post) is forecast to have an extent of surface melt similar to record-setting events in 2012.

    That said, the current hourly forecasts still shows the high precipitable water, the persistent crazy high temp. anomalies stretching across long arc of northern Siberia, and for much of the forecast period, also on the North American side.  The forecast shows snow cover depth north of Greenland essentially gone by June 10 2019 (scale is cm).



vs. June 10 in 2018. 


It took until June 22, 2018 for snow depth image to match the June 10, 2019 forecast.  While that does not seem like a cataclysmic difference to my untrained eye, a 12 day earlier loss of snow cover with the sun at near maximum height, combined with many blue sky hours also in the forecast, does seem notable in terms of insolation.   

Enough covering my tracks.  What I definitely did get right and did not exaggerate was an Arctic weather expert ringing the alarm bell about the forecast as it appeared at that time, and the Arctic sea ice situation overall.  Vote climate.
 

338
Arctic sea ice / Re: The 2019 melting season
« on: June 07, 2019, 02:08:20 AM »
    A friend and colleague who is a PhD climate scientist, and whose work is regularly cited in this forum ... (but I'll leave his name out of it, even though Sean said it was OK to cite him... ooops)

    ....and who has watched Arctic weather for many years, brought the subject up at the end of a day-job phone conversation earlier this week.  He said it's hair raising, that he's never seen anything like what (as of Tue. June 4), was forecast for the next 10 days, esp. the latter part of that forecast as we head into mid-June.  One that I was not previously aware of was the amount of precipitable water in the air masses flowing into the Arctic.  e.g. https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.pwtr

  And the story is not limited to the Arctic sea ice.

    One striking example as he walked me through a hall of horrors of forecast images was an image of the infamous ~97% Greenland surface-melt day (edit: days in July & August 2012.  The one that was so bizarre that NASA seriously thought the satellite sensor must have gone bad because such a reading was unprecedented and unfathomable.  (And which my friend on the phone said GFS foresaw at least a week in advance, just to defend the underloved GFS a bit.  BTW - GFS is getting the FV3 upgrade June 24!). 

     Then he took me to the 10-day 10th day Greenland surface temp image for this JUNE   And while not covering the almost the entire GIS as happened in the 2012 blasts, the 2019 forecast image was for a 10-day average, not a single day, and the 2019 image was for mid-June, not July or August.

    Another striking image was the projected very early 2019 timing for loss of ice/snow cover north of Greenland.

    While I'm a long time climate hawk and ASIB watcher, not being a climate scientist and being only a recent ASIF lurker with a post count even smaller then Trump's tiny little extremities (I'm talking about his hands, jeesh, get your mind out of the gutter!), it's been difficult for me to interpret the "contextual significance" for all the recent hubub about the 2019 melt season. 

     So for others of you watching the discussion from that perspective, the point of this post is that a PhD climate scientist with expertise and experience in Arctic weather (while acknowledging that forecasts can change, that June is not the whole summer, and that the Arctic is fickle) is having his own "Holy Cow" moments this week, to put it politely.  Stay tuned.  And vote climate. 

339
According to recent study as described by NSIDC Arctic Sea Ice News & Analysis - June 4 edition:
https://nsidc.org/arcticseaicenews/
 
    "While Arctic sea ice extent is declining sharply, it is also highly variable from one year to the next. Scientists from the Max Planck Institute for Meteorology and the University of Stockholm have proposed that this strong variability is closely related to fluctuations in the air temperature above the Arctic Ocean driven by atmospheric heat transport into the Arctic from lower latitudes.
 
      In contrast to previous assumptions, they argue that other factors, such as the ice-albedo feedback, cloud and water vapor feedbacks, and oceanic heat transported into the Arctic together explain only 25 percent of the year-to-year sea ice extent variations. Most of the sea ice variations are thus directly caused by mid-atmospheric temperature conditions..."

340
Arctic sea ice / Re: What's new in the Arctic ?
« on: May 31, 2019, 02:21:52 AM »
RE Tealight #348
Nice work!  That would be great addition to NSIDC website.

341
As noted by Sedziobs in #1333 of the 2019 Melt Season forum:
A sneak peek at GFS FV3 running in parallel mode is at
https://www.tropicaltidbits.com/analysis/models/?model=fv3p&region=nhem&pkg=T2ma&runtime=2019053012&fh=6

342
Arctic sea ice / Re: Basic questions about melting physics
« on: May 31, 2019, 01:59:15 AM »
Doing some homework by reading the Slow Transition forum. https://forum.arctic-sea-ice.net/index.php/topic,933
    To expedite access to the take home points for others still getting their arms around the original question, here are some selected items from that discussion that provide a plausible explanation.  The quotes are from 2014 and I think they hold up well 5 years later.

1. Chris Reynolds #6  July 2014
"...2007 and 2012 saw massive gains in volume despite delays to the onset of melt. This is because the rate of growth of ice for open water and thin ice is extremely fast. The following graphic is from Thorndike 1975."



2. Chris Reynolds #49  July 2014
"…the contention that future April Arctic Ocean volume will be set by ice growing to thermodynamic equilibrium thickness (TET) from September to April, then further volume loss events leading to net thinning of the pack and enabling further increases of melt season losses of volume look unlikely.   Because with a mainly first year ice pack further drops in volume in years like 2012 will be followed by rapid recoveries to the volume implied by the TET around the time of those drops within a few years at most (Tietsche et al)."

3. From Chris Reynolds  Dosbat Blog.  http://dosbat.blogspot.com/2014/07/the-slow-transition.html
    "I am becoming convinced that the approximate levelling of PIOMAS volume over the last few winters is telling us that the pack is becoming dominated by FYI, whose thermodynamic equilibrium thickness is largely setting the peak volume in April."

    "I was persuaded that the loss of MYI represented energy that would then have to go into melting FYI after the MYI had declined. However because FYI regrows in the winter it vents this notional energy. The energy that once went into melting MYI is thus vented into the atmosphere and radiated to space in autumn/winter."

343
Arctic sea ice / Re: Basic questions about melting physics
« on: May 30, 2019, 03:28:47 PM »
     Simpler framing of the original question makes the answer easier to see.
Original mystery (to me at least) was why wasn't PIOMAS volume decreasing in sync  with loss of old think ice?

    My new dope-slap-forehead observation - winter maximums have declined, but not as much as summer minimums (maxima, minima for those of you who remember 7th grade Latin).  Thus it is clear that winter refreeze has increased along with declining summer minima.  Not enough to fully compensate for increased summer losses, but enough to reduce their impact on winter maxima.
 
   As helpfully pointed out by Oren and others, that is indeed the case.  As to why winter ice gain increases with declining summer minima, two mechanisms are
1) thinner ice is able to increase thickness faster, and
2) ice cover acts as an insulator, thus less insulation means faster cooling in the following fall/winter. 
     There may be other mechanisms in addition to 1 and 2 (changes in cloud cover or wind patterns?).  And within 1 and 2 there are more detailed explanations for how/why they work.

   So nothing new here in this post!  I just thought anybody who was also puzzled by the original question, lack of 1:1 correlation between dramatic loss of older, thick ice, and the more subtle (but consistent trend) of PIOMAS ice volumes would find a bit of catch up and summary useful. 

   Two particularly interesting and useful points that arose -
    a) thick ice does not necessarily mean old ice.  Thinner fractured ice floes are more susceptible to being transported by wind or currents into thicker piles.
   b) salinity differences account for why older ice is more resistant to melt; and younger, saltier ice is less resistant to melt (though not everybody seems to agree about the chemistry at the molecular level).
   

344
Arctic sea ice / Re: The 2019 melting season
« on: May 28, 2019, 03:06:34 AM »
https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.snowd-mslp
   
 
     Climate Reanalyzer shows large drop in snow cover between May 27 and June 6, and dominance of high pressure air masses over Arctic on June 6.  PDF attached.

345
     NOAA's new FV3GFS replacement/upgrade for GFS scheduled to go live on June 24.  This is 3rd scheduled operational date, first delayed by shutdown, then they found a temperature bias issue which needed correction.  I think this time they will actually do it. 

     FV3GFS 1.0 not expected to provide better accuracy right away, but the new platform provides a better foundation for development.  Original plan call for extending hourly runs at 13km resolution from current 10 day limit out to 16 days.  (Current GFS runs at 35km resolution and 3-hour time steps for days 11-16).

   New model will make better use of the awesome new GOES East and West satellites.  (Think color TV vs B&W still pictures).

   A version 2.0 of FV3GFS planned for a year after 1.0 version.  2.0 will bring new physics package.  And about a year after that, timeline shows a possible resolution improvement down to 9km.  Improved ensemble forecast system scheduled for FY2020. No mention of seasonal forecasting until at least FY2023. 

   This all driven by playing catch-up with ECMWF that called Superstorm Sandy path change a day earlier than GFS.  Of ECMWF isn't standing still either.  This is the kind of arms race we need.

346
RE #1866 "Because thermodynamics means the new ice grows to 2 meters plus thick across the Arctic Basin over every winter?"

   But that 2 meter new ice growth happens with or without old thick ice.  So it seems that a year with less returning old thick ice from previous year + summer freezing/thickening would result in less volume than an earlier year that had more returning old thick ice and gets the same amount of  summer freezing/thickening.

   The only way I can figure it is that with lower portion of old thick ice, the young ice that replaces it allows faster thickening.  Perhaps the thinner ice cover over water allows more heat loss and thus more thickening, whereas old thick ice is a better insulator and is less dynamic.

347
Arctic sea ice / Re: Glossary ... for newbies and others
« on: May 27, 2019, 06:20:52 AM »
AMOC - Atlantic Meridional Overturning Circulation 
- Atlantic Ocean component of the global thermohaline circulation.  The "Gulf Stream" is a subcomponent of the AMOC.

348
With dramatic loss of old thick sea ice since 2010, I would expect that PIOMAS Sept. minimum would show stronger downward trend for 2010-2019, but while the long term trend is obvious, the last 10 years have been fairly flat.  Why doesn't loss of old thick ice show up more in PIOMAS Sept. minimum volume?

349
Arctic sea ice / Re: The 2019 melting season
« on: May 27, 2019, 12:30:56 AM »
RE 1158 JDAllen,
RE 1160 johnm33
Thank you gentleman. 
    Sorry for not noticing the forecast forum.  Good stuff.

FWIW 2019 GISTEMP global surface temp is heading for 1.18C above 1850-1900 average, number 2 all time rank, still has a shot at #1.
  Globally, even though ENSO is waning, due to ENSO lag effect on temperature, no major cooling in sight for second half of the year. 

RE context for 3-letter acronym was question I had to answer in order to post.
"Cause of Arctic sea ice melt (3 letters)" = AGW Anthropogenic Global Warming

350
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 11:06:26 PM »
AGW?

<Yup; N.>

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