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Arctic Sea ice 2015

Discussion in 'Environmental Discussion' started by bwilson4web, Mar 27, 2015.

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  1. tochatihu

    tochatihu Senior Member

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    Wanted to mention this:

    Josefino C. Comiso and Dorothy K. Hall
    Climate trends in the Arctic as observed from space
    WIREs Clim Change 2014, 5:389–409. doi: 10.1002/wcc.277

    This journal publishes useful and accessible reviews. Publisher Wiley hopes to be paid though, so off to the library with you.
     
    #21 tochatihu, Apr 9, 2015
  2. tochatihu

    tochatihu Senior Member

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    If a WIRES review is not really what you're after, how about this?

    Race - Sailing The Arctic Race

    Anybody who explains what are "high performance volcanic-fiber offshore yachts" gets an automatic 'like'.
     
    #22 tochatihu, Apr 9, 2015
  3. fuzzy1

    fuzzy1 Senior Member

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    Basalt fiber? That had completely escaped my attention, until this thread, despite living atop it a good portion of my life.
     
    #23 fuzzy1, Apr 9, 2015
    Last edited: Apr 9, 2015
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Beautiful charts associated with the above research:
    http://science.gsfc.nasa.gov/sed/content/uploadFiles/scihi_hydrobio_ppt/2014_1_highlights.pdf

    Abstract: The surface temperature in the Arctic increased at a rate that is 3.5 times larger than that of global temperature from 1981 to 2012. The amplified warming is manifested in many cryospheric parameters. Among the most visible is the 13.5% per decade decline in the extent of the multiyear ice cover since 1979 and the 2.1% per decade retreat of the snow cover since 1967. Moreover, the temperature of the active layer of permafrost has increased while glaciers worldwide and the Greenland ice sheet have been losing mass at the rate of 275 and 228 Giga-tons per year, respectively, in recent years. These results suggest that profound changes in the ecology, environment and climate of the Arctic are imminent.​

    Bob Wilson
     
    #24 bwilson4web, Apr 9, 2015
  5. tochatihu

    tochatihu Senior Member

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    #25 tochatihu, Apr 17, 2015
    bwilson4web likes this.
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    New bookmark: CryoSat Operational Monitoring - Overview

    Switching from area to volume is easy for me. Today's satellites are so much better than what we had before. I was a little surprised that melt water remains a problem. Just another puzzle to work out.

    Bob Wilson
     
    #26 bwilson4web, Apr 17, 2015
  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Interesting May, 2015:
    [​IMG]

    Bob Wilson
     
    #27 bwilson4web, Jun 20, 2015
  8. bwilson4web

    bwilson4web BMW i3 and Model 3

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    [​IMG]
    • We had several weeks of warm weather in the Huntsville and the SE in early June when Tropical Storm "Bob" ran a loop around us.
    • I understand Europe is suffering a heat wave too: Historic Heat Scorches Europe - International Weather Blog Weather Blog
    • There appears to be a pattern:
      • Miiddle latitudes get hot and Arctic melting slows
      • Middle latitudes get cool and Arctic melting accelerates
    I'm getting the impression that monitoring the cool/heat of the middle latitudes gives a good indication of whether the Arctic is going to suffer greater/lessor melting. In effect, as the polar cold air travels south, it is replaced by warmer southern air masses that reduce freezing in the winter or accelerate melting in the summer.

    Another source:
    [​IMG]

    Bob Wilson
     
    #28 bwilson4web, Jul 5, 2015
    Last edited: Jul 6, 2015
  9. austingreen

    austingreen Senior Member

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    #29 austingreen, Jul 6, 2015
  10. austingreen

    austingreen Senior Member

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    Think carbon fiber, but these use crushed basalt, which is cheaper than typical carbon fiber. basalt is created when lava cools, so they call it volcanic as a marketing term.
     
    #30 austingreen, Jul 6, 2015
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  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I was looking at the data last night because I noticed one of the NSIDC charts had not been updated since June 1. Thanks to a clue from 'liar liar' mojo, I found the Danes had kept theirs current:
    [​IMG]
    Sure enough, the less rapid rate of melting coincided with a slug of warm air over Huntsville and CONUS when tropical storm 'Bob' did the big loop through Texas, Oklahoma and then points East. I was looking because I knew Alaska has been in some fairly high temperatures. The reason has to do with the northern coast of Alaska:
    [​IMG]
    A sliver of clear water on the coast was evident but something else. What caught my eye was the dark, cob-web, ice areas . . . the signature of decompressed ice. Solid ice does not have that cob-web, blackish areas. It looks like in another week or so, the Arctic navigation routes will open. Only the northwest passage appears to have solid, compressed ice. Regardless, the Danish surface chart shows 2015 is in the same general area as 2014 and 2013.

    Albedo only counts if the sun is shinning on the surface. Today, the Arctic has nearly 20+ hours of daylight. In contrast, Antarctica is in pretty much darkness, nearly 24 hours.

    There are some other curious things about Antarctica and the earth's orbit. Stuff I'm looking at for sea level changes.

    Bob Wilson
     
    #31 bwilson4web, Jul 6, 2015
  12. austingreen

    austingreen Senior Member

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    yep, that interactive chart I showed had artic and antartic. 6 months from now its dark in the artic but bright in the antartic.

    Not important for sea extent, but grace is measuring loss of antartic thickness. Melting is not from warmer surface temperatures by warmer currents under the ice.
     
    #32 austingreen, Jul 6, 2015
  13. fuzzy1

    fuzzy1 Senior Member

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    Isn't GRACE measuring only the mass of ice resting on solid ground?

    I thought the warm current melting was only under floating ice, where the buoyancy of floating objects means there is no mass difference for GRACE to measure. Floating ice thickness must be measured by other means, instruments on other satellites.
     
    #33 fuzzy1, Jul 6, 2015
  14. austingreen

    austingreen Senior Member

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    errors get greater but it is my understanding that scientist are using GRACE to estimate ice loss in the West antartic ice sheet (WAIS) and East antartic ice sheet (EAIS) Here is a paper talking about errors. Revisiting GRACE Antarctic ice mass trends and accelerations considering autocorrelation
     
    #34 austingreen, Jul 6, 2015
  15. fuzzy1

    fuzzy1 Senior Member

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    This one does mention 'offshore ice', but does that mean floating ice, or ice that is thick enough to reach, and be supported by, the seafloor?

    From previous discussions, I had taken WAIS and EAIS to mean non-floating ice. The wikipedia page on WAIS currently says "The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves."
     
    #35 fuzzy1, Jul 6, 2015
  16. austingreen

    austingreen Senior Member

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    Yes I was talking about ice shelves for ice extent not free sea ice. Part of these ice shelves float. I didn't think that they were counting free floating sea ice for arctic or antarctic ice extent but I could be wrong.
     
    #36 austingreen, Jul 6, 2015
    Last edited: Jul 6, 2015
  17. bwilson4web

    bwilson4web BMW i3 and Model 3

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    My reading indicates ice flows into the ocean remains a significant part of the mass loss. The glaciers are flowing into the seas faster in part because the undercutting, warm water lubricates their motion. The ice shelfs are restraining but not blocking the flow.

    Last night I was looking at CRYOSAT-2 that has suspended Arctic measurements until September because melt-water screws up the sounding. But I've not found their Antarctic data yet (web page under construction.) But there is a much simpler metric: Sea level as a global thermometer | PriusChat

    Bob Wilson
     
    #37 bwilson4web, Jul 7, 2015
  18. fuzzy1

    fuzzy1 Senior Member

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    As far as GRACE is concerned, my understanding was that the portions of the ice shelves that float and can be undermined by warm sea water, are indistinguishable free sea ice and from open seawater. To be seen by GRACE, the ice column mass must be different, i.e. heavier, than the equivalent open water. This heavier column weight will automatically cause it to be grounded, which in turn should prevent the circulation of warm water underneath.
     
    #38 fuzzy1, Jul 7, 2015
  19. austingreen

    austingreen Senior Member

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    The ice is less dense (lighter) than the salt water but this difference in density is smaller than land based ice, so estimates have more margin for error. I was tired when I responded last night, of course sea ice is counted in ice extent. Grace is one of those satelites that allows us to measure that too. We also have more information than grace, gathered though. Here is a paper from last year using radar from planes, that talks about one of the theories of why antarctic ice is thinning.

    Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet
     
    #39 austingreen, Jul 7, 2015
  20. mojo

    mojo Senior Member

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    The warm water is caused by geothermal volcanic melting of the ice from below.
     
    #40 mojo, Jul 7, 2015
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