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Messages - Glen Koehler

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51
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 07:00:41 AM »

      While some allowance must be made for possible sensor misinterpretation, the July 21 NSIDC ASI concentration map makes the Beaufort look like a fortress ready to fall.

52
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 03:07:44 AM »
Do you expect a 2nd place, MH?
1st-highly unlikely
2nd- good chance but weather will need a spell of favourable melt conditions at some stage
3rd or lower - quite possible if weather stays favourable for ice retention.

      Given gerontocrat's summary below, I think that "good chance" for 2nd (i.e. 3.96M km2 JAXA Extent) is a very, very good chance:
<snip> In every year from 2007 to 2019 remaining melt results in an extent below 3.96 million km2, which was the 2nd lowest extent in 2019.

     But the ice does not care what we say about it.  It will tell us exactly how much it will melt over the next few weeks. 
     This poem comes to mind:

   Ice asks no questions, 
      presents no arguments,
         reads no newspapers,
           listens to no debates.
     
    It is not burdened by ideology,
       and carries no political baggage
           as it changes from solid to liquid.

    It just melts.

                                 ~ Henry Pollack
------------------
   
  But of course, we like to guess at the future. 
     Here are some measures of our predictive ability:

      Improved Volume prediction accuracy as melt season observations become available.
R-square reduction in variability derived from R values posted by Stephan at https://imgur.com/a/O82kzZZ

      Linear model estimate for 2020 September average PIOMAS Volume before any 2020 observations:
 3.9M km3 (1.2 – 6.6), (95% of cases expected to fall within 1.2 – 6.6M km3, i.e.  +/- 2.7M km3).
   
      With MARCH observation as predictor, confidence interval (CI) reduction for September average Volume estimate: 4%.  Width of 95% CI with March observation: +/- 2.6M km3.
      With APRIL Volume observation, confidence interval reduction: 7%.  Width of 95% CI with April observation: +/- 2.5M km3.
      With MAY Volume observation, confidence interval reduction: 32%.  Width of 95% CI with May observation: +/- 1.9M km3.
      With JUNE Volume observation, confidence interval reduction: 63%.  Width of 95% CI with June observation: +/- 1.0M km3.
      With JULY Volume observation, confidence interval reduction: 83%.  Width of 95% CI with July observation: +/- 0.5M km3.
      With AUGUST Volume observation, conf. interval reduction: 94%.  Width of 95% CI with August observation: +/- 0.2M km3.

      The same approach for Extent shows the R2 reduction by having observations at the end of March, April and May is insignificant.  Estimate error reduction only reaches 22% by the end of June, and 56% at the end of July.

53
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 03:24:39 AM »
Made a table of 2020 extrapolations with some particular dates set as sort of "mile markers" for a quick reference to how the ice is doing. I think these three options bound outcomes pretty well.
   Thanks Killian.  Those are very interesting comparative extrapolations.  I find them more informative than the debate about the degree of compaction.  The fact that your extrapolation from 5 low melt years stills ends up at 3.6 M km2 is remarkable and well below the straight line trend, and rougly 8-10 years ahead of where 2020 "should" be on that trend line (eyeball estimate).

    Taking 2012 out of the "Worst case" scenario yields an estimate similar to the "Bad case" scenario at ca. 3.4-3.5.  That reinforces a final estimate of around 3.5.  That would still leave 2012 in 1st place, but not by much. 

      I wonder how warm water melt momentum in 2020 is still unexpressed in the real time measurements.  And with warmer water the chance of cyclone is also lurking in the wings.  Putting those pieces together suggest that 2020 is heading for a near miss 2nd place without any additional anomalously strong melt weather between now and minimum, and may even replace 2012 without any dramatic melt weather, due to momentum.
     
      While another GAC 2012 is unlikely, if there is a strong storm, then it looks like 2020 has a very good chance of going below 2012.  As other ASIF posters have noted, regardless of the record, the ice condition looks terrible and already has one thinking about what kind of setup 2020 is creating for 2021.  The 2019 + 2 = 2021 tag line used by ASIF member be cause is looking prophetic. 

       But that's next year.  The end game for this year looks to be dramatic and historically significant.  We will have numbers soon.
 

54
     Does anybody care to disabuse me of my conjecture that there is a nonlinear relationship between ice thickness and melt resistance - with decrease in melt resistance curving down faster than the linear % decline in thickness - due to qualitative differences in thinner vs. thicker ice?

     The fact that ice accumulation is radically nonlinear with increasing thickness is accepted as established fact, e.g. the curve published by Thorndike 1975
.

     Earlier this year I pitched the idea that the reverse is true for melting, with 1 meter thick ice melting at twice the rate of 2 meter ice (0.8 cm/day vs. 0.4 in the example shown):  .

     Those who actually understand the physics of ice melt shot down that theory, explaining that the energy flows involved in summer melt are not simply the reverse of winter freeze.  Correction which I gratefully accept, .... but

     ....even if a straight reversal of the thickness-freeze rate curve to estimate thickness-melt rate curve is too simplistic to be valid, that still leaves open the possibility, and (in my mind at least) the near certainty that the melt rate vs. thickness ratio is not a stricltly linear 1:1 ratio.  I have no idea what it would be, but it I'm almost certain that the melt rate for 1 meter vs. 2 meter thick ice has to be greater than 1:1.  And that ratio has to be even greater for 0.9, 0.8, 0.7 etc. meter thick ice vs 2 meter ice. 

      It is well documented and accepted that the chemical and structural characteristics of Arctic sea ice varies with thickness.  Those qualitative differences have to make some difference to the melt rate. 

      This is not merely an academic question.  An accelerating melt rate with declining thickness would have major consequence for acceleration of Extent and Volume losses as average thickness continues to decline as shown on the chart posted by gerontocrat at https://forum.arctic-sea-ice.net/index.php/topic,119.msg275579.html#msg275579  (A chart which I nominate for the ASI Graphical Hall of Fame).

      Which leads to a vision of the near future of the ASI showing accelerated melt to the same weather conditions and energy inputs of previous years, and even more so as continued cumulative global warming, exacerbated by Arctic amplification, increases energy inputs into melt seasons and reduces winter refreeze potential (and greater potential for Arctic cyclones, and jet stream weakening to allow warm air mass incursions, etc.). 

      If so, the drop from 4 million km2 September Extent to 3 million could occur in a shorter time frame than the observed trend for the drop from 5 million to 4 million.  And with average ice thickness in late summer approaching 1 meter, a nonlinear melt response for thinner ice would  accelerate even more for the drop from 3 million to 2 million km2, and even more than that for the drop from 2 million to 1 million km2. 

    (I suspect that dropping below 1 million km2 would complicate things because that final ice has resistance due to protection within bays etc. that would compensate for a thin ice melting effect).

      By extrapolation, the linear Extent decline trend reaches zero decades later than the Volume trend.  But of course that is impossible, because when there is no Volume, there is no ice left to create Exent.  So the Extent trend has to eventually start accelerating to curve downward to catch up with Volume by the date when they both reach zero.  I think that thin ice melt acceleration will be a major contributing factor (along with mobiillty for export, fracturing, surface area and possible others), that will cause that to happen.

     Is there a fallacy in this line of thinking?  What alternative mechanism accounts for the  required unification of Extent and Volume as they approach zero.  Binntho I'm talking to you!  This is right up your alley and I haven't seen you post for a while.

    One more conjecture.  I think that as the average thickness in the High Arctic Seas, as shown in gerontocrat's graph, is approaching 1 meter in September, the accelerated thin ice melt effect, which might have been relatively inconsequential until now, will become an increasingly important influence.  As a result, there will be "Extent goes poof" events of increasing scale and frequency over the next 10 years, resulting in a BOE by the early 2030s if not before.

55
Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 06:23:34 PM »
Here's the year-to-year comparison of the ASI (from AMSR2) maps for 19 July.
This year is unprecedented for the amount of ice cover lost by this date on the Russian side.

     The 2020 heat anomaly and high pressure systems so far this melt year are causing historically low-for-date Extent, with hard to understand not-1st place low Area loss (but I'm not trying to reignite that discussion), and low but not 1st place PIOMAS volume.  Given the conditions, even with the high Extent and Volume at start of season, I am surprised the ice is not in worse shape than it is.

     Looking at the deep purple areas of highest concentration and most likely to survive ice in the link posted by slow wing, July 19, 2020 looks surprisingly strong with a larger area of deep purple  high concentratoin ice than all but 3 of the 15 years displayed at
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0719

     The years with more deep purple being 2005, 2009, and 2017.   With 2020 showing LESS deep purple than 2006, 2007, 2008, 2010, 2011, 2012, 2014, 2015, 2016, and 2018.
 
      Expanding the comparison to deep + light purple gives a less dramatic comparison, but still does not make 2020 stand out like it seems it should.

     How can that be?  I am probably giving too much importance to an eyeball area estimate of deep purple, but this is one the main images we use to track Arctic ice status.  One unaccounted for factor is remaining melt momentum.  My guess is that 2020 at this point has more energy in the system and thinner, more vulnerable ice than prior years, thus greater losses in store for remainder of melt season than most earlier years (2012 excepted).  I also suspect that thickness losses are a hidden weakness in the 2020 ice.

     I think the High Arctic thickness graph posted by gerontocrat at https://forum.arctic-sea-ice.net/index.php/topic,119.msg275579.html#msg275579 says a lot about the trajectory of ASI decline in recent years.

     Compare the thickness for the 2000s vs. 2010s and now 2020.  I think that the effect of the 0.6 meter (25%) thickness reduction between 2000s and 2020 has more importance than the ratio implies.  That would be because there are important qualitative differences between 2.4 meter and 1.8 meter average ice thickness.  The thicker ice is older, has lower salinity and higher density, and thus higer "melt resistance".  If so, then the 25% reduction in thickness could represent a 33% (just to have a number) decrease in melt resistance. 

     (2017 is an exception somewhat, but it was coming off of high melt year in 2016 followed by an extremely warm winter.  By my theory then, 2017 with its thin ice should have been another near record low September Extent and Volume.  2017 ended up above the straight-line trend for Extent, and just below the trend for Volume.  But the thickness factor does not have to overwhelm melt season weather -- which 2017 apparently lacked -- in order to be true as an important influence).

     If this conjecture is correct, then adding the qualitative effect of thicness reduction to the already low Extent/Area/Volume values puts 2020 even lower compared to all prior years.

     I'll go farther out on a limb to propose that there is a break point around 2 meters ice thickness.  That is about the amount that can freeze in one winter or melt out in a melt season.  I have to wonder if going below 2 meters thickness initiates a nonlinear accelerated reduction in melt resistance.  It certainly reflects the shfit from MYI to FYI which we all agree has been one of the big story lines since 2007.  And speaking of 2007, I think that it, not 2012, is the epic year that should get more attention in terms of understanding the effects of melt season weather and the modern progession of ASI decline.  No disrespect to 2012, but 2007 was a knockout punch that came out of nowhere.  The MYI ice loss that year set the stage for all that has happened since.

56
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 05:49:21 PM »
   Climate Reanalyzer got stuck by a power blip yesterday.  Some of the Arctic forecast animations are already updated to July 19, the rest will be back online in few hours by 1800 UTC July 19.  The updated pressure forecast no longer shows a sub-990 low pressure system.

57
Arctic sea ice / Re: Glossary ... for newbies and others
« on: July 19, 2020, 04:30:42 PM »
Thanks for the correction - Conterminous United States (the lower 48)

National Weather Service - Table of Commonly Used Acronyms and Abbreviations
https://www.weather.gov/mdl/about_acronyms

58
Arctic sea ice / Re: Glossary ... for newbies and others
« on: July 19, 2020, 04:03:05 AM »
CONUS - Continental U.S.  Frequently used acronym in meteorology.

59
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 19, 2020, 03:35:48 AM »
Vox_mundi posted a Navy Arctic Roadmap https://forum.arctic-sea-ice.net/index.php/topic,3183.msg275158.html#msg275158
   That document has an interesting graphic showing projected of ASI Extent in 2030 vs 2012. 
    A rough eyeball comparison of the area for their 2030 area suggests that it is about 30% of the 2012 area. 
    Given that 2012 JAXA & NSIDC Exent minimums were 3.18 and 3.41 million km2, respectively, the 2030 Navy projection at ~30% of 2012, is a pretty close fit to what a 1 million km2 September minimum BOE event would look like.

     When that happens, it will be a headline for a day, and the ice will begin winter increase shortly thereafter, and humanity will go back to ignoring planetray climate disruption.  Or perhaps we will be wiser by then.  A lot can happen in 10 years.  It certainly will for the Arctic ice.  The question is whether human response will evolve accordingly.  Vote Climate as if your life depended on it.  Annoy your famiy and friends by harping on it.  They will love you for it later.


60
Arctic sea ice / Re: Shift in timing of ice minimum over the years
« on: July 19, 2020, 02:24:30 AM »
   Previoius chart is solar radiation at top of atmosphere.  Tealight posted a chart of insolation at surface.  The low sun angle in the Arctic increases the amount of atmosphere through which solar radiation must pass which reduces the level reaching the surface.  Chart posted by Tealight shows values for latitude in 10 degree increments so you don't have to guess where 80N falls between 60 and 90.
    Based on comment in 2020 Melt thread by GoSouthYoungins
https://forum.arctic-sea-ice.net/index.php/topic,3017.msg274806.html#msg274806
that insolation driven melt essentially ends in last week of August (which I have not verified from other sources, but seems reasonable) I added estimated dates for start and end of insolation melt season.  Residual melt from warm water melt would account for the remainder of melt season until September minimum.
    Caveat:  I don't know any of this stuff, just making back of the envelope estimates.  Corrections encouraged.


61
Arctic sea ice / Re: The 2020 melting season
« on: July 18, 2020, 05:23:22 PM »
mercator 0m (ocean) temperature with amsr2uhh overlaid at 80% transparency. amsr2 0% concentration has been set to fully transparent. jun1-jul17
    Up thread I asked if pack ice disconnecting from continental and large island shores might lead to increase in ASI pack rotation.  Near the end of uniquorn's animation, just as the periperhal ice detaches from shorelines, the whole pack starts rotating.  Example of cause and effect, or just selective observation of a random correlation?
 
    The animation also shows active export from Lincoln Sea via the Nares Strait, which seems especially significant as it could be reducing what little is left of MYI.       

62
Arctic sea ice / Re: The 2020 melting season
« on: July 18, 2020, 06:29:53 AM »
<snip>  Many of the great weather forecasters here on ASIF have already mentioned this, but a head Met at an agency in the UK seems to agree.
    James Peacock is a great meteorologist who follows sea ice closely. He watches the ASIF, and might even have an account here.
    Today he posted what might be some scary news for the ice if it comes true. His model runs support what others have said that we might see a strong low over the Beaufort in about a week. Since the Beaufort is the last remaining hold out for the ice, that will be bad if it happens. It will churn up warm water and cause mechanical breakup of existing floes.
   Peacock - "...like putting the sea ice into a washing machine...'
     ... and set to warm rinse cycle.

GFS has pressure going down to 984 not a cataclysmic 965, and the storm lasting about two days, but still bad news for the ice...
 
GFS surface temp forecast for July 24



GFS cumulative precip forecast for July 17-24


63
Arctic sea ice / Re: The 2020 melting season
« on: July 18, 2020, 05:59:44 AM »
NSIDC July 16 update
https://nsidc.org/arcticseaicenews/2020/07/siberian-downward-slide/
"Through the first half of July 2020, sea ice extent declined by an average of 146,000 square kilometers (56,400 square miles) per day, considerably faster than the 1981 to 2010 average rate of 85,900 square kilometers (33,200 square miles) per day."

"Air temperatures at the 925 mb level (about 2,500 feet above sea level), as averaged over the first half of July, were unusually high over the central Arctic Ocean—up to 10 degrees Celsius (18 degrees Fahrenheit)"


64
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: July 18, 2020, 12:44:19 AM »
Just a reminder, to really damage the ice a bomb cyclone not only needs low pressure, it has to be relatively long-lived and positioned so as to create long fetches. Right now I’m more concerned about the low earlier in the forecast bringing excessive heat and moisture from Siberia.
I agree 100%.
Phoenix - was telling us that worth a post?  I don't mind your willingness to poke at consensus understanding (as long as you stick to facts and don't cherry pick)... and my kvetching about your post is equally off-topic. 
   I'm just asking for a bit more discretion in sharing your musings.

65
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 11:35:16 PM »
Anyone who knows what the most intensive Arctic cyclone in July is? Have there been any cases below 970 hpa in July?
I've seen them appear in forecasts ; I remember noting once that there were several in a forecast on gfs .. 2017 or 18. They didn't materialize . b.c.
     be cause's caution about forecast verification is duly noted, but if that beast actually occurs (965?!) we are into twilight zone strangness for ASI.

    I think the answer to Lord Vader's question must be 'not since accurate modern monitoring began'.  There has only been a total of 3 below 970 in August since 1979, and August is a much bigger cyclone month than July.  Those three events were in 2012 (all time lowest at 966.4, 1995 at 966.9 in 2nd place, 1991 at 969.2 in 3rd place, and 4th place also in 1991 at 970.5.
(A younger and less temperate Friv must have been freaking out in 1991!)

      The frequncies in graph are from a population of 1618 August Arctic cyclones.  Graph title is "Frequency distribution of August (1979–2012) Arctic cyclone properties for (a) central pressure".  It is from The great Arctic cyclone of August 2012 by Ian Simmonds and Irina Rudeva.  GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L23709, doi:10.1029/2012GL054259, 2012. 
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL054259


66
Arctic sea ice / Re: Latest PIOMAS update (July 2020)
« on: July 16, 2020, 07:21:51 AM »
   Even though it is a short range of dates comparison between, it is surprising to see the 2007 value lower than the others (except for 2014). 

   2007 was a true blow-out year, especially for MYI ice reduction, from which the Arctic has never really recovered.  It would stand out above 2012 except the freakish GAC that pushed 2012 into new territory. 

    As for 2020, if this year's May and June melt pond conditioning and the current July roast-a-dome don't produce a 1400 km3 drop, it seems like that could only be because there is less ice to melt.

67
Arctic sea ice / Re: The 2020 melting season
« on: July 16, 2020, 07:08:21 AM »
     It looks like soon all the ice abutting continental coasts and major islands will be melted out.
How much difference does that make to Arctic-wide ice pack rotation? 
Does that free up the pack to rotate faster with consequences for transport into Barents, Fram Strait,  ESS, and Laptev melting zones, with possible addition of Ekman uplift of warmer subsurface water?

68
Arctic sea ice / Re: The 2020 melting season
« on: July 16, 2020, 06:56:04 AM »
Meanwhile, the Beaufort is dragging its feet and is almost highest in the AMSR2 record..
     The July 22 HYCOM thickness forecast posted by Milwen at
https://forum.arctic-sea-ice.net/index.php/topic,3017.msg274198.html#msg274198
and the HYCOM concentration forecast posted by OfftheGrid at
https://forum.arctic-sea-ice.net/index.php/topic,3017.msg274287.html#msg274287
both indicate that the Beaufort is unlikely to serve as a defensive wall for much longer, as it is beginning its own period of rapid retreat.




69
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 16, 2020, 12:51:36 AM »
Let's not get bogged too much in definitions.
    At the cost of adding one more distracting message, I feel compelled to congratulate and thank Oren for superb moderator service during what is turning out to be quite a rodeo this year as the ASI appears to enter the next phase.  You've handled the usual food fights, occassional personality disorders, and the inevitable cases of topic drift with a diplomatic and effective aplomb.

70
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 09:02:20 PM »
Also HYCOM 7 day forecast. Whole CAA is basically gone.  :o
  ...plus ice retreat along north coast of Greenland.

71
Arctic sea ice / Re: Albedo-Warming Potential
« on: July 08, 2020, 08:07:41 PM »
Thanks Comradez, that provides a much better understanding of the AWP situation.  I was looking at the AWP graph as actual energy input.  Clear vs cloudy sky cover radically changes that interpretation.

72
Arctic sea ice / Re: Temperatures at Eureka, Nunavut, Canada
« on: June 29, 2020, 04:24:22 PM »
    My speculations were for non-professional weather stations.  NOAA or Env. Can. ownership and the photos indicate professional-grade weather stations with technical support, so far less likely to have issues with low-quality sensors, improper placement etc. that not infrequently occur at non-professional stations.

73
Arctic sea ice / Re: Temperatures at Eureka, Nunavut, Canada
« on: June 29, 2020, 02:56:01 AM »
could be be an elevation difference?
They are both down as 10m. Still showing a difference of 7 C beteeen the 2 stations.
       Alternate possibility.  May sound too simple to be true, but it wouldn't be the first time to have incorrect readings from improperly operated weather sensors.  If one of the sensors is missing a radiation shield or does not have an aspiration fan to move ambient air across the sensor, then it can report much higher temperatures than a properly protected sensor.  Or if the sensor is placed near a building, pavement, or (God forbid, but it happens) on a roof, it will give falsely high warnings during sunlight hours.  Did the two sensors agree until direct sunlight returned?

      And there is always the possibility of a sensor for which everything was done right, i.e. properly shielded, aspirated, located and calibrated --- but then it just goes bad.  Temperature sensors are robust, but anything can break.
     When did temperature readings from the two stations begin to diverge?  An abrupt change in readings for one of the sensors could indicate equipment malfunction.

74
That's an interesting diagram, oren!  The one thing that isn't intuitive for me, though, is why the initial longwave energy emitted from the surface is 110 units.  Where does that come from? 
      Way outside my lane and just my understanding, but in case it's useful:  It is counterintuitive to see 110 emitted when only 89 were supplied, and thus a -29 deficit.  Everything has to balance in the end, so who makes up for those -29?  My guess is that shortwave energy that reaches the surface, is absorbed and converted to longwave (infrared), and then reemitted upward from the surface, makes up that difference. 

      That means that the Earth receives more shortwave than it emits, and emits more longwave than it receives.  The net energy has to balance, but within the total energy budget, energy from one wavelength bucket can translate into energy in another wavelength bucket, i.e. from shortwave to longwave. 

      A black tar road receives a lot of downward shortwave and a lesser amount of downward longwave radiation.  The shortwave is absorbed and converted to longwave, and the tar road emits a lot of longwave back up (the road gets hot in the sunshine).

      My objection to Walrus' statements is not so much about the unsupported statements about a specific mechanism that this discussion has evolved into, but conflating the "warmest temperatures of the year" to overall cooling, and using the comparison of 1986-2015 vs 1900--1960 observations to conclude that the current change is towards cooling, esp. when the projections looking forward show increased warming for all measures, including for warmest day of the year. 

      The original question was about why a specific location would be warming less than the rest of the planet.  The Tamino article addresses that very question with his usual superb skill, including a discussion of and links to recent peer-reviewed studies for anybody who wants to go into it at depth.  I assume that if Walrus' hypothesis had any credence, then the articles that investigated the southeastern U.S. "warmhole" would have included discussion of that as a factor, and that it would have thus shown up in Tamino's summary of the findings of those studies.  But it does not appear in that discussion, which is not surprising because if it were true it would apply everywhere and would not be a localized regional influence.

       I have not confirmed that assumption and not interested enough to do so.  But if somebody wants to, that would one way to close the book on Walrus' hypothesis.

75
     Thanks binntho.  A simple "Like" wasn't enough gratitude for your taking the time to stand up for fact-based evidence. 
      Nobody needs to get their feelings hurt.  Some ideas are correct and hold up, some not.  You don't know until you ask a question or propose an answer.  That is core to the scientific method.  It can't answer every question but it is the best method we have, esp. for addressing objective, physical questions.  Tamino provides the definitive discussion of the "warmhole" question.  I hope the Stupid Questions thread can move on. 

76
     My statement about a "minority of U.S." was with respect to and true for the summer temperatures graphic, it was not referring to the warmest days graphic.   

      RE "The warmest temperatures of the past two decades in the U.S. are below those of the first two decades of the 20th century.  That precedes the dust bowl!"
     Not true.  The comparison for the warmest days image is 1986-2016 vs 1901-1960.  Thus the comparison to earlier years includes all of the dust bowl years. 

     The reason for my objections to your argument is your assumption that "just because the warmest temperatures are not increasing."   Yes they have increased if the reference point is warmest temperatures of the day, i.e. average daily max.  Only looking at the extreme warmest day of the year leads to a distorted impression.  That is why folks are giving you grief about this. 
   
      And by putting it in the present tense you imply that those warmest day of the year temperatures are not increasing at present.  But you have not shown data to support that. The data you cite are observations over two extended periods, not the current rate of change.  To the contrary, the trend forecast estimates that the warmest temperature of the year will be higher in the future. 

      Neither of us have shown data about the current rate of change for warmest temperature of the year.  I am saying that a) we need a comparison of more recent data to evaluate that question and b) that the warmest temperature of the year is not the real story anyway, and focusing on that narrow measure obscures the larger issue.  Your stance seems to be that past observations for warmest temperature of the year represent their current rate of change, which they do not.  And that the warmest temperature of the year deserves more attention than broader measures, with which I simply disagree.

77
<snip> The data supports the hypothesis.
     Only in a narrow cherry-picking view.  Your narrow focus on the extreme events in one region is misplaced. 

 
     The observed summer-only temperature observations show only slightly cooler in a minority of U.S. (note: even the light peach-colored areas in the Southeast were warmer, only the areas in blue were cooler relative to earlier in the century)


     Moreover, the narrow focus on the warmest days of the year is temporary.  All areas are expected to show higher temperatures on the warmest days of the year going forward.
   

     
    The focus on observed extreme high temps in one region misses that point that AGW is making the planet hotter in ways that are not good for human civilization and most other existing species. 

    A wider view that does not focus on the exceptional case is more accurate.  Here are the observed regional U.S. changes in max and min daily temperatures.  All the regions show increase for both daily average Max and Min temperatures.



      And that slightly wider view is still narrowly focused on one country.  The global picture is even more compelling.

78
What's causing Arctic amplification? https://www.skepticalscience.com/print.php?r=67

      Thanks KiwiGriff.  Your post deserves more prominence than the "Stupid Questions" thread. 
   
       It speaks to the centrality of the ASI to the future habitability of our planet... sooner than most people realize.  What happens when we start hitting BOE in September, then BOE in August and October a couple of years later?  With July (with near peak insolation) next up on the stove.  And before each month reaches BOE, EVERY month trends toward more open water and lower albedo. 

      IMHO we are very close to even more dramatic ASI loss acceleration.  That in turn poses major risk of systemic shifts in the weather patterns that we depend upon for agriculture and everything else.  By soon I mean that 2030 is looking bad.  Even that is an understatement given that we have already lost >75% of the September ASI volume, so 2020 is already bad.  But the situation is likely to get much worse in the next 10 years unless we act forcefully in the right direction.  I hope we all vote and act as if we are in a planetary crisis, because we are.
 

79
Arctic sea ice / Re: The 2020 melting season
« on: June 19, 2020, 03:48:56 PM »
June 14-18.2019.
The CAA is simply swamped with melt water.
Nares also
As we reach peak insolation...

Source: www-grida-no—graphicslib

80
       RE June 17 pressure system forecast at http://204.197.0.55/MEmodel/ArcticSnowCover18Z2020-06-17.png

Questions for those with meteorological knowledge: 
      What keeps those multiple adjacent low pressure systems on the Russian side from converging into one big low pressure system? 
   
      Or the multiple high pressure systems on the North American /GIS side from converging into one big high pressure system? 
     
      If either set did converge, would the intensity of the resulting combined system be more or less intense? 
     
      And if both the Russian/low and North American/high groups consolidated, would that create a Titanic dipole?

81
Arctic sea ice / Re: The 2020 melting season
« on: June 13, 2020, 03:29:05 AM »
      Alternate views of GFS snow depth forecast:  June 12, 18Z
http://204.197.0.55/MEmodel/ArcticSnowCover18Z2020-06-12.png


      Poof!  June 17, 18Z
http://204.197.0.55/MEmodel/ArcticSnowCover18Z2020-06-17.png

 
      The June 17 image also shows good view of dipole.  The positioning looks conducive for clear sky over Pacific side and some ice movement away from the ESS and Laptev Sea into the CAB.  But neither the high pressure or the low pressure system are very strong so wind speed where they meet should not be very strong, thus fairly wide spacing between isobar lines.  (My attempt to interpret the image for those even less familiar with pressure maps than me.  Caveat: I am not a meteorologist, I just play one on the internet). 

82
Arctic sea ice / Re: The 2020 melting season
« on: June 13, 2020, 02:56:59 AM »
        GFS cloud cover forecasts.  Granted these are 9 and 10 day forecasts, but the near-term forecast images show almost as much clear sky.  I just wanted to see what it looked like at peak solstice insolation.  Light blue is clear sky over ice.

         2 hours past solstice hour June 21 at 0Z
http://204.197.0.55/MEmodel/ArcticClouds0Z2020-06-21.png
           Lots of clear sky and insolation over much of the Pacific side and ca. 33% of the entire Arctic Ocean (eyeball estimate).

42 hours later June 22 at 18Z
http://204.197.0.55/MEmodel/ArcticClouds18Z2020-06-22.png
           Even larger area of clear sky, covering ca. 60% of Arctic Ocean.


83
      From NSIDC September 2012 seasonal summary:
http://nsidc.org/arcticseaicenews/2012/10/poles-apart-a-record-breaking-summer-and-winter/

      'Weather conditions prevailing over the summer of 2012 were quite different from those in 2007.  The summer of 2007 featured unusually high sea level pressure centered north of the Beaufort Sea and Greenland, and unusually low pressure along northern Eurasia, bringing in warm southerly winds along the shores of the East Siberian and Chukchi seas (3 to 5 degrees Celsius, or 5 to 9 degrees Fahrenheit above normal), favoring strong ice melt in these sectors and pushing the ice away from the coast, leaving open water.  The pressure pattern also favored the transport of ice out of the Arctic Ocean and into the North Atlantic through Fram Strait.

     In contrast, the summer of 2012 saw unusually low pressure along the Eurasian coastal seas and extending eastward into the Beaufort sea, most prominently over the East Siberian Sea, with unusually high pressure centered over Greenland and the northern North Atlantic. Air temperatures for summer 2012 were above average over most of the Arctic Ocean (1 to 3 degrees Celsius, or 2 to 5 degrees Fahrenheit), most prominently over the Beaufort Sea, where, because of the pressure pattern, winds were anomalously from the south.

     Melt began two to three weeks earlier than average in the Barents and Kara seas, leading to earlier retreat of sea ice in the region; however, air temperatures remained below average during summer in this region. This points to the impact the continued loss of old, thick ice is having on the ability of the sea ice cover to survive summer melt. Other than the August storm, the pressure pattern in 2012 does not appear to have been as favorable in promoting ice loss as was the case in 2007, and yet a new record low occurred."

(Siberia on left side, Greenland on right, Bering Strait at the bottom)

84
     I do not have a clear understanding of why a dipole weather pattern over the Arctic is so influential for ice melt.  Here are my guesses:

     1.  High pressure system over the Pacific side of the Arctic creates clear skies and thus higher insolation and thus greater direct exposure of ice surface to solar radiation and thus greater surface melt.

     2.  High pressure over Arctic results in downward moving air mass with warming temperatures reaching the surface.

     3.  Low pressure system paired with high pressure system creates a wind tunnel where the two systems meet.  When oriented to create a strong Pacific to Atlantic wind field, this pulls ice away from the Pacific side and into the Atlantic side where it is closer to export out of the Arctic.
Ice already on the Atlantic side is pushed toward exit via the Barents Sea and out the Fram Strait into rapid melt zones?

      4.  Strong wind field disrupts (what is left) of the Beaufort Gyre nursery for growth of multi-year ice. 

      5.  A strong coherent wind field caused by a dipole creates more Ekman pumping, reduces thermocline layering, and brings heat from deeper levels to the surface?

      6.  Strong winds in any direction move the ice around more, creates more wave action, increases fracturing, and thus more surface area exposed to melt through direct contact with sea water?

      7.  Dipole pattern brings in large volume of warmer air from the lower latitudes into the Arctic, displacing normally colder Arctic air mass?

      8.  Dipole pattern also brings in large volume of moist air that has higher heat carrying capacity?

     These are questions, not statements.  Which of them are accurate?
       

85
Arctic sea ice / Re: MOSAiC news
« on: June 11, 2020, 03:49:24 PM »
   Thanks uniquorn.  The May 15 Fram export event shows as a very brief pulse, but what was going on from mid-March though ca. April 5?  The buoys were moving fast for several weeks.  I don't remember any dramatic weather at that time.

86
Hi FG - My guess (and that is all it is) is that aerosol reduction could also cause increased radiation losses out to space during the winter as the aerosols can also add to the insulating effect of the atmosphere, thus fewer particles = less insulation = more winter heat loss. 

      During the 24 hour nights of polar winter there is no counteracting cooling effect of aerosol particles reflecting incoming shortwave radiation.  So the cooling effect, which dominates during summer is not active during winter.

      But I don't pretend to understand the details of these interactions, just thought I'd take a shot it since you asked.  It would be great to get an answer from somebody who studies this stuff.
 

87
     Inside Climate News article on aerosol drop impact on Arctic sea ice
https://insideclimatenews.org/news/08062020/sulfate-emissions-coronavirus-arctic-heatwaves

     "Overall, this winter wasn't particularly warm, but now that's flipped around in the last month and we're really seeing the effects," says Mark Serreze, director of the National Snow and Ice Data Center (NSIDC). "Big holes are opening up along the Siberian coast where it's been the warmest."

     "This Central Arctic heatwave may not be a one-off event only occurring in spring 2020, researchers suggest. Rather, if levels of global industrial air pollutants continue to fall due to the Covid-19 pandemic, the current Arctic warmth could be a bellwether of what's to come later this summer when sea ice melt annually kicks into high gear."

     "Indeed, in a 2017 study, scientists posited that the sulfate aerosols released due to human activity masked the decline in Arctic sea ice in the mid-20th century, before the Clean Air Act went into effect, and actually led to periods of ice growth."

     "Using earth system computer modeling, his simulations showed that sulfate aerosol reductions in Europe since 1980 could potentially explain a significant fraction of Arctic warming over that period. Specifically, the Arctic received approximately 0.3 watts per meter squared of energy, warming by 0.9 degrees Fahrenheit on average as Europe's sulfur emissions declined."

     " "We conclude that air quality regulations in the Northern Hemisphere, the ocean and atmospheric circulation, and the Arctic climate are inherently linked," his 2016 Nature Geoscience study stated. "

88
Arctic sea ice / Re: The 2020 melting season
« on: June 09, 2020, 07:58:15 PM »
      Based on Climate Reanalyzer graphs of GFS, the Beaufort Sea ice is in for a rough week with surface temps, clear skies and precipitable water incursions all pointing towards accelerated melt. 
https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2
https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-tcld-topo (light blue = clear sky above ice)
https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.pwtr

89
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 09, 2020, 02:44:37 PM »
    Thanks Uniquorn.  I think the animated 2010-2020 thickness map is the single best tracking tool we have.  I hope you keep doing them.  The timings were perfect for watching repeatedly.

90
Arctic sea ice / Re: The 2020 melting season
« on: June 08, 2020, 04:59:24 PM »
http://ocean.dmi.dk/arctic/meant80n.uk.php
The DMI 80N shows the temp curve remaining below 0C. We seem to dodge the bullet of a prolonged peak on the front end.
   DMI 80+N temp chart is observations not forecast.  And a biased one at that.  Moreover, during melt season the surface temperature is essentially capped near the freeze/thaw point as energy goes into melting ice not raising air temperature.  Thus even during a strong period of melt those temps will stay near freezing as long as there is still widespread ice to melt.

925 mb temp anomalies for May 1- June 5 in the selected years 2012, 2016, 2019, 2020. 

     Thanks JayW - the 2020 anomaly is stronger than what I expected.  As Niall cautioned, I don't know how closely the 925hPa correlates with surface impact, but seeing the big dark blob of red for 2020 really makes me wonder about the current preconditioning state of the ice, and what that suggests is coming, as igs noted upthread about a potential cliff. 

     I agree that qualitative condition deserves more attention.  I suppose thickness and concentration serve as qualitative metrics.  But thickness is intermittent and concentration is about relative measures of surface coverage not the physical state of the ice.  I'm wondering if there are other qualitative measures, such as a measure of ice continuity and pack integrity.  Perhaps an index that goes from 1 for completely solid continuous ice to near 0 for completely fractured rubble.  Is there anything like that?  I also haven't seen a melt pond roundup for May yet.   

91
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 07, 2020, 10:12:21 PM »
Another one. This is a forecast for June 30 based on the melting rate in 2019. June 30 is blue, May 31 is red.
    Both versions are great.  I like the second that shows May 31 vs June 30 best.  Also agree that animation would be a nice addition (and more work no doubt!).  Whether comparative or not, animated or not, having some form of these bubble graphs at monthly intervals (or at mid-month if there is a PIOMAS update) would be an informative benchmark for tracking seasonal progression.  Thanks for introducing these.

    Maybe 5 or 10-year average melt rate instead of 2019?

    WOW - both Kara and Laptev GONE by June 30!

92
Arctic sea ice / Re: Arctic energy balance
« on: June 03, 2020, 02:24:42 AM »
Thanks Freegrass.  That Total Precipitable Water video explains a lot of ecosystem/habitat variation around the planet.  In particular the grasslands of central and northern Asia, and why the polar regions are considered deserts despite being dominated by water ice.  It also demonstrates better known moisture habitat relationships like the Amazon and central African rain forests.  And finally it demonstrates the intermittent and somewhat random, but over time, reliable variation between wet and dry that supports agricultural regions in the mid-latitudes.

93
Arctic sea ice / Re: The 2020 melting season
« on: May 29, 2020, 12:54:02 AM »
Again, on the topic of the Kara sea. Here's a zoom in. 24./26./28.05.
       Thanks for those superb and highly informative images blumenkraft.  Am I correct that the reported Extent and Area values for that location on those three days is likely to show virtually no change?  Yet the change is dramatic when ice quality and thickness is considered.  That is the monster hiding under the bed for ASI loss.  It doesn't change much for a long time as it absorbs energy and rots out .... and then it falls prey to some intermittent melting event.

        A similar point (albeit in a far distant context) about smooth model projection tractories vs. the bumpy ups and downs of what actually happens is made in a short video by Peter Sinclair https://climatecrocks.com/2020/05/28/new-video-breaking-bad-news-in-florida-keys/
 
       That may seem off-topic, but my point is that the same principle applies to Arctic melt and is becoming increasingly relevant as 2020 early season conditioning softens up the ice for a potential sucker punch later.  Because of the ways we measure/perceive changes, they don't make an impression until a threshold is exceeded and then change seems to erupt suddenly.  But it was building all along.

       Loss of MYI was strike 1 of 'below the surface' change.  Thickness decline leading to structural weakness, fracturing and increased mobility is strike 2.  Strike 3 is when the rot is no longer hidden.

       As Juan Garcia's tag line says, Extent losses mask the other dimension of Thickness loss which is not as intuitively apparent to our visually based monitoring.  Thus, an entire dimension of ASI decline is essentially hidden, and accumulates with less notice.  Then another GAC (or current forecast for large areas of clear sky within 24-->10 days before solstice, https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-tcld-topo) comes around and Wham!, a whole lot of built-up change potential suddenly becomes manifest, appearing as a dramatic new event even to folks who have been watching all along. 

       I'm preaching to the choir of course, and not revealing anything new to the people who come here.  But those pictures compelled me to comment on ice condition as an under-appreciated dimension, and as the defining characteristic of the 2020 melt season so far.  Call me Chicken-Little, but that ice looks dangerous.  And the records indicate that reaching that condition in May is anomalously early for the Kara Sea.

       All of which is a long-winded way of saying what A-Team (I think) once said.... one of these days... the ice will go "poof."  The nature of complex, interactive, chaotic systems is to not see change coming until it suddenly happens.

94
Arctic sea ice / Re: Nullschool Forecasts
« on: May 28, 2020, 05:32:25 AM »
       FG - I'm not asking for a seminar, or an explanation of the reasoning for your alarm, just the name of the thing that grabbed your attention.  Is it the wind?  The temperature?  Particular locations? Precipitable water?  Is it a strong low-pressure system near the Bering Strait?  Or high pressure dominating the CAB?

       Since the image clips don't show the scale legend to allow interpreting what the colors mean, and since most of us won't bother to go over to NullSchool to find the legend bar, the colors in the images are intriguing but not quantitatively informative.  If you are referring to temperature in a certain region, use your text message to tell us how high they are such that they grabbed your eye.

       If you just say "Oh My God!" with no text to identify what it is you are referring too, and post an image without a legend, it may not be clear to us what has your attention or what the image is representing. 

       Yes, we can watch the clip and get some sense of it, especially if we are used to NullSchool images.  So it's not that the images are useless without some explanation and a legend.  But if you are going to the trouble to make a clip, why not gift wrap it just a little bit to make it more meaningful? 

       When this is all in the history books, and your great grandchildren are looking back at what their 'Oompah' did during the great meltdown of 202?, make them proud.  Until then, thanks for your efforts.  I enjoy the freshness of your wonder and curiosity, and have learned from your queries.  Like you, I am a non-expert tuning into this drama, and just trying to figure out what's going on.  Even though it is a horror show when you consider the larger implications, it is a fascinating process to watch.

95
Arctic sea ice / Re: MOSAiC news
« on: May 28, 2020, 02:38:55 AM »
   I hope somebody is tabulating these direct observations of surface melt with readings from satellite sensors to help calibrate interpretation of signals to distinguish between air moisture vs. surface melt vs. melt ponds vs. open water.  That would add to the knowledge being gained by having the MOSAIC folks present at the scene of the crime during melt season.

96
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 09:14:14 PM »
Slater's model has picked up the current preconditioning  and thinks it is favourable for strong melting way into July.
It predicts 7.34 m km² for July 13th, currently nosediving ...

   Wow, if that forecast verifies, then 2020 would be 600K and 8% below the previous records for July 13 Extent in 2019, 2016, 2012. 

    It is useful to have Phoenix provide a skeptical check on habitual ASIF catastrophism (as in "this year is the big one!"), but it is also true that 2020 has come out of the gate strong, and that the current Extent and Volume numbers do not yet reflect the preconditioning that has occurred.  In addition, the current GFS forecast shows surface temperature for most of the Arctic Ocean above 0C from May 29 - June 3, combined with substantial areas of clear sky and what seems to be high amounts of precipitable water along the Atlantic front and north of Greenland (but I lack the historical perspective to interpret the precipitable water forecast).   

    I worship at the church of the long term linear trend, which has the 2012 volume record remaining intact for 2020 but then a ca. 50% chance of falling in 2021, and increasing each year thereafter.  For Extent, the trend estimate shows the 2012 record being safe for 5-10 years.  While it is far too early to say anything definitive about 2020, considering the recent conditioning, the current GFS forecast, that scary albedo graph posted by Sublime_Rime, and the Slater model forecast (which has been pretty accurate in recent years), 2020 seems to have a greater than 50% chance of going below the 2012 volume record.  The Extent record from 2012 was due to a freak event (the GAC) that is unlikely to be repeated in 2020, so is less likely to be surpassed.  But that is less important anyway, as I also worship at the church of Volume vs Extent with the Rev. Juan C. Garcia.

97
Arctic sea ice / Re: Glossary ... for newbies and others
« on: May 24, 2020, 08:26:02 PM »
CR = Climate Reanalyzer

98
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 03:07:34 AM »
       A while back Stephan calculated the R values for Volume and Extent at the end of each month to the following September minimum.  Accepting a few assumptions (that seem reasonable), squaring those values gives the R2, a measure of the percent of interannual variation that can be explained by knowing those values, and thus reducing the width of the confidence interval for estimating the subsequent September minimum.  https://forum.arctic-sea-ice.net/index.php/topic,2348.msg257955.html#msg257955

Improved Volume prediction accuracy as melt season observations become available. 
R-square reduction in variability derived from R values posted by Stephan at https://imgur.com/a/O82kzZZ

        Linear model estimate for 2020 September average Volume before any 2020 observations:  3.9M (1.2 – 6.6) km3, (95% of cases expected to fall within 1.2 – 6.6M km3, i.e  +/- 2.7M km3).
   
      With MARCH observation as predictor, confidence interval (CI) reduction for September average Volume estimate: 4%.  Width of 95% CI with March observation: +/- 2.6M km3.
      With APRIL Volume observation, confidence interval reduction: 7%.  Width of 95% CI with April observation: +/- 2.5M km3.
      With MAY Volume observation, confidence interval reduction: 32%.  Width of 95% CI with May observation: +/- 1.9M km3.

      With JUNE Volume observation, confidence interval reduction: 63%.  Width of 95% CI with June observation: +/- 1.0M km3.

      With JULY Volume observation, confidence interval reduction: 83%.  Width of 95% CI with July observation: +/- 0.5M km3.

      With AUGUST Volume observation, conf. interval reduction: 94%.  Width of 95% CI with August observation: +/- 0.2M km3.

-----------------------------
      Those values indicate that until we have the end of May, and really the end of June, volume observations, prior observations don't give us much foresight about the September volume minimum.  Which in turn suggests that melt season conditions (temperature, cloudiness, and storms) that take effect in June, July, and August are the primary determinants for the September volume minimum.  (Some of those conditions, such as melt pond formation, may have been established earlier, but do not manifest as changes in volume until after May 31).  Thus, about 68% of the variation in September minimum Volume becomes apparent after May 31 (100% minus 32% = 68%).

     The same approach for Extent shows the R2 at the end of March, April and May at insignificant level, only reaching 22% by the end of June, and 56% at the end of July.  Thus, changes that manifest in July and August account for 78% of the variation in September minimum Extent (100% minus 22% = 78%).   

      An expert analysis by Walt Meier and NSIDC concluded  “Plotting the de-trended maximum versus minimum extent (Figure 2) shows a near-random distribution.”  “The seasonal maximum extent and the September minimum extent are not correlated...“  "because summer weather conditions strongly shape the September minimum.”
     

Figure 2. This plot compares de-trended maximum extent (x-axis) with minimum extent (y-axis). The yearly values shown are calculated by subtracting the linear trend value for that year from the total extent.  Credit: W. Meier, NSIDC.  From “Maximum extent is not predictive of minimum extent” https://nsidc.org/arcticseaicenews/2020/03/

99
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 02:45:30 AM »
      FWIW - Useful to clarify the question and frame of reference.  Phoenix puts more emphasis on conditions that affect the ice in the CAB and along the northern edge of the CAA that is considered likely to be the last to succumb to September melt.  Other folks generally refer to conditions for the Arctic overall. 

       So another question within the discussion is to what degree is the "last to go in September" ice isolated vs connected to conditions in the larger Arctic system.  For example, if the Kara Sea gets roasted early this year, as appears to be the case, how much does that affect the overall ASI September minimum?

100
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: May 23, 2020, 01:01:53 AM »
      Good to see those neighbors keeping a six-foot distance between them as they reconnect after a long winter.

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