Sea Ice UPDATE: JAXA Extent graph for 08/29

August 29, 2012

Compare this product of the Japan Aerospace Exploration Agency to the National Snow and Ice Data Center below.  More perspective on the comparison with recent years.

A correspondent asks:

“Am I wrong to infer a relationship between degree of minimum extent and timing of minima?  It seems that larger ice volumes hit their minimum earlier in the year.  Could we thus expect this year’s ice extent minimum to be later still, perhaps even into October?”

No way I’m going to go out on a limb here. We are thru the looking glass at this point, but just eyeballing the graph (always dangerous) – it  would seem not out of the question.
Experts – I know you’re out there – feel free to weigh in.

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16 Responses to “Sea Ice UPDATE: JAXA Extent graph for 08/29”

  1. rayduray Says:

    Off Topic

    Here’s something I haven’t seen before. A nighttime satellite view of Hurricane Isaac as it approached the Louisiana coast last night:

    http://www.space.com/17355-hurricane-isaac-night-photo-space.html

    Compare to this daytime view of Katrina in all her Cat 5 glory before landfall:

    ***


  2. The slope of the 2012 graph is almost linear since the beginning of June. All the older graphs start to slow melting in early August — but this year doesn’t appear to have slowed at all. It certainly looks like the minimum will be later than ever before.

    More melting means that there is more latent heat in the water, and higher air temperatures and higher levels of GHG means that the rate of cooling is going to be slower, so by definition the minimum will be lower and later; all else being equal. Also, smaller pieces of thinner ice have greater surface area as a ratio to the volume of the ice, so the “giant slushy” will keep melting…

    Neil

  3. rayduray Says:

    Re: “Could we thus expect this year’s ice extent minimum to be later still, perhaps even into October?”

    Highly unlikely. I’ve seen a range from September 7 to September 16 for the date of minimum sea ice extent. It would be extraordinarily unlikely for this to get pushed back by two weeks. Recall from your study of the Earth’s seasons that by September, the Arctic is really just about at the end of the insolation season.

    Another data point is to look, for example, at the climate of Barrow, AK. http://en.wikipedia.org/wiki/Barrow,_AK#Climate

    What we find is that in September, the average daily temperature is 0.1 C. In October, that plunges to -8.0 C. In other words, October is far too late into the season to accommodate further melting.


    • Remember this is seawater — what is the freezing temperature of the Arctic ocean? I wonder how the salinity changes as the ice melts? Is sea ice salty, or does all the salt get left behind in the water? If the sea ice is not salty (which is my assumption), then the seawater gets saltier as the ice freezes, and less salty as it melts. So, the more it melts, the freezing point gets higher, as well.

      Can someone enlighten me on this process?

      Neil

      • rayduray Says:

        Re: “Remember this is seawater — what is the freezing temperature of the Arctic ocean? I wonder how the salinity changes as the ice melts? Is sea ice salty, or does all the salt get left behind in the water? If the sea ice is not salty (which is my assumption), then the seawater gets saltier as the ice freezes, and less salty as it melts. So, the more it melts, the freezing point gets higher, as well. Can someone enlighten me on this process?”

        I’ve not forgotten that the Arctic is salty. :)

        The freezing temperature depends on a number of factors. Obviously water temperature, but also air temp and degree of turbulence in the water. In September, there can be melting of ice in the open ocean due to wave action while the sheltered edges of the ocean start to lock up with new ice.

        As the ice melts, what is being observed is a distinct stratification of the Arctic. There’s more fresher water at the surface and there’s some evidence of less vertical mixing, or increasing stratification. At least that’s what I’ve read.

        No sea ice is salty. As ice is formed, a brine comes off the forming ice and it sinks, increasing the salinity at depth.

        You might address your question on the Arctic Sea Ice blog, where there are many knowledgeable contributors who have studied this topic and are willing to share their wisdom.


  4. I agree with Ray. Insolation is the limiting factor and barring a major shift in our orbit…………………….

  5. jasonpettitt Says:

    At 12 o’clock is a little shy of a million square kilometres of ice breaking free. I gotta say, I’m starting to feel uneasy about this year’s melt. It really is starting to feel like watching the end of the world :(

    • jasonpettitt Says:

      Needless to say, I’m hoping that the melt season ends early, like it did last year.

    • rayduray Says:

      Hi Jason,

      Re: “At 12 o’clock is a little shy of a million square kilometres of ice breaking free.”

      I think you have a misconception of what the various colors represent in this static image. While there was a large “breakaway” of ice in early August’s cyclone, the current situation in the High Arctic is pretty stable right now without much surface wind or current flow moving the ice around. If the Arctic were to lose a mass of ice by migration, it would be flowing down the Fram Strait to the east of Greenland. This is not the case. What you are seeing with the various colorations in that image is the degree of compaction versus the “swiss cheese” effect. The lighter shades the further toward the Bering Strait you see are not migrating. They are simply very unconsolidated. Sort of a big slurpee. That ice will likely melt in place, and not by migration.

      Let me suggest you take a peek at this short animation showing the decline in area and extent of the Arctic sea ice this season:

      http://neven1.typepad.com/blog/2012/08/peeking-th.html

      And here is perhaps an even better animation that I linked to via the Sea Ice Blog: http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html

      What I am seeing here is simply the world’s biggest ice cube melting in place. :)

      • jasonpettitt Says:

        Oh, I hadn’t really got as far as thinking what the exact fate of said ice would be – I only noticed that some very large chunks are becoming disassociated from the main volume of the sea ice as they disintegrate – from where one way or another I only suppose they will be increasingly vulnerable to melt.

        Like I said, I’m hoping the melt season will end early.


  6. Solar hasn’t been the dominant factor for a couple of weeks. It’s the heat in the water that is doing the work. The ice is melting from below.

    The extra heat is probably due to direct heating of open water earlier in the year. It’s also possible there has been some mixing from the Atlantic, which is unusually warm this year compared to normal past conditions.

    Anyway, it seems to me that looking over past years, while there are day to day wiggles, the weekly time scale slope of these curves historically does not change rapidly. So I am going out on a limb and suggesting several more weeks like this, even though the sun has almost set at the pole.

  7. rayduray Says:

    For Jason and other interested souls,

    The question was when can we expect the lowest area/extent of Arctic Sea Ice?

    The best source I’ve got is Neven Acropolis, and herels the answer he’s provided for past seasons:

    CT SI Area:

    2005: Aug. 30
    2006: 16
    2007: 7
    2008: 8
    2009: 9
    2010: 8
    2011: 10

    IJIS SI Extent:

    2005: 22
    2006: 14
    2007: 24
    2008: 9
    2009: 13
    2010: 18
    2011: 9

    All dates for September unless specified.

    ***
    Ray again. As you can see, we do not have a very good record back in time as to the date to minimum extent/area. Certainly we humans have zero capability in this regard prior to 1979 when satellite data first became available.

    Speaking in broad terms, the latest date of minimum extent/area is September 24. That was the IJIS estimate for 2007. NSIDC has a date for 2007 of September 16 on a rolling 5 day average basis. So, the Sept. 24 date is suspect.
    I’d say that the likelihood of an October final minimum is something on the order of a Sigma Five event, Or way less than 1 in 1,000,000: http://en.wikipedia.org/wiki/Standard_deviation

    The likelihood of a minimum in August seems even more remote for 2012, considering the SSTs.

    My intuition is that the minimum extent/area will occur on my birthday, September 17. And it will amount to something on the order of 3.4 MM Sq. Km. The real shocker will be when people understand that the minimum volume of sea ice is a mere 10% of what it was in the 1970s.


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