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Messages - Glen Koehler

Pages: [1]
1
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 14, 2019, 07:23:27 PM »
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.

2
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

3
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.

 

4
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 11, 2019, 04:49:20 PM »
     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?

5
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.

6
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)

7
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?

8
     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."

9
    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. 





10
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

11
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?


12
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.
 

13
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. 

14
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..."

15
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.

16
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

17
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."

18
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).
   

19
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.

20
     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.

21
Arctic sea ice / Re: "Stupid" Questions :o
« on: May 28, 2019, 02:14:00 AM »
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.

22
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.

23
Arctic sea ice / Re: "Stupid" Questions :o
« on: May 27, 2019, 06:04:31 AM »
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?

24
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

25
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 11:06:26 PM »
AGW?

<Yup; N.>

26
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 11:00:55 PM »
     Bottom melting is a known driver but seems to get little monitoring.

    1)  In addition to temperature, cloud cover, insolation, wind, ice extent/area, ice thickness, ice age, ice condition, melt pond momentum, and land attachment, does the amount and temperature of Atlantic current inflow act as a driving factor for melt? 

    2)  Are there tracking and forecast maps/summaries for Atlantic inflow volume and temperature to use as predictors?  Known historical patterns or correlations with September minimum.
     
    3) Ditto Pacific inflow, but my understanding is that Atlantic inflow is a stronger influence.

    4)  Exploring my ignorance out to its edge, it seems like there might be a trend for cloudier Arctic summer weather with increased open water.   To the extent that there is skill, multi-month June-September Arctic weather outlook would be interesting.
 
PS #1088 JDAllen - interesting point about melt ponds not just changing albedo but also serving to conduct air temperature into ice.  Never heard that before but it makes sense.

Test question "What is causing Arctic Sea Ice loss" - 3 letter acronym.  Stumped me.



   

27
Arctic sea ice / Re: Glossary ... for newbies and others
« on: May 24, 2019, 08:12:55 PM »
to add DMI - Danish Meteorloglical Institute, usually referring to their chart of average temperature north of 80N.  My understanding is that those temperatures are not area-weighted.  So small circle at 89N gets as much weight as much larger area at 80N.

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