Still Trying To Make Sense Of The NSIDC Ice Age Maps

As I have been discussing, NSIDC shows a sharp drop in multi-year ice since the end of July, but very little drop in 1-2 year ice. It makes little sense to me how this selective loss could happen. The video below shows this as a smoother transition :

Julienne suggested that I make a comparable animation of the UIUC concentration maps.

As you can see, there was low concentration ice “above” the pole for a few days in early September – in a region of July multi-year ice. Some of it probably melted out. But why did MYI selectively melt and leave younger ice behind?

Also, it appears that there was a lot of MYI loss north of Canada, in a region where the ice remained high concentration all summer.

I guess we will ses what happens this winter….

About stevengoddard

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21 Responses to Still Trying To Make Sense Of The NSIDC Ice Age Maps

  1. Anything is possible says:

    I follow the ice charts issued daily by the Canadian Ice Service fairly closely, and they give a more detailed breakdown of the ice content.

    Link :

    They show that the ice, in the Canadian Arctic at least, is often composed of a complex mixture of old, second year and new ice, something that the highly simplistic charts issued by the NSIDC fail to represent.

    In short, I would suggest that the devil is in the detail….

  2. Julienne Stroeve says:

    Steve, circulation continued to move ice north of Canada towards the Beaufort Sea, so part of the reduction in MYI is from transport in that region. Additionally, it’s important to remember that the FYI could have been heavily ridged/rafted in the region around the pole, and therefore could have been thicker than the MYI in the same region. Substantial thinning occurred following the 2007 minimum, with buoy data showing 2 meters of basal melt in some regions, and ICESat and ERS SAR data showing thinner ice thickness in the MYI regions in spring 2008 than in any other year in their data records. It would not be surprising that MYI was thin enough to melt out compared to more heavily ridged/rafted FYI.

    • Julienne,

      Does that imply that the turquoise ice – which turns green over the winter – will be thicker than this years MYI was?

      • Julienne Stroeve says:

        that’s too simple a way to view it. Thermodynamic ice growth of FYI is around 1.6 m. But depending on ice motion, i.e. a stronger Beaufort Gyre that transports ice from the western Arctic to the eastern Arctic and causes ice to thicken by ridging and rafting on the Siberian coast before returning to the central Arctic can cause regionally much thicker ice. That doesn’t mean all FYI is ridged/rafted, but that processes can happen that cause heavily ridged/rafted ice in certain locations of the Arctic basin. While I do not know if the ice around the pole that was FYI was heavily ridged or rafted, it certainly could have been under the strongly negative AO from this past winter that strengthened the Beaufort Gyre.

        Without knowing the physical properties of the ice you are concerned about, nor the direction of the ice transport between the two time-periods you are looking at, you cannot blindly conclude that the ice age maps are wrong. The ice age maps are based on weekly ice motion vectors that are used to track each individual ice parcel in a 25 sq-km pixel. Errors in the ice motions from comparisons with buoy data show monthly errors of less than 1 pixel. The movies of ice age from this summer show open water areas developed near the pole that contained some of this MYI, the movies also show transport out of Fram Strait and from the Canadian Archipelago toward the Beaufort Sea.

      • But we do know (if the maps are correct) that 1-2 ice survived immediately adjacent to MYI which didn’t.

        That implies that the 1-2 ice was thicker than the MYI.

    • Julienne, you say: “Substantial thinning occurred following the 2007 minimum, with buoy data showing 2 meters of basal melt in some regions, and ICESat and ERS SAR data showing thinner ice thickness in the MYI regions in spring 2008 than in any other year in their data records.”

      OK, but… what about the real measurements of thickness in 2009?: Lange 2010 ( or Haas 2010 (

      • Julienne: “Errors in the ice motions from comparisons with buoy data show monthly errors of less than 1 pixel. ”

        I`ve looked the buoy 5312 of the IABP:

        I`ve drawn its last two months drift with a red line in the map of the end of july from Maslanik.
        I`ve drawn with a red cross its final position in the map of september from Maslanik.
        I have highlited a black box around the buoy, in both maps. I suppose the overall drift of that black box is quite similar to the drift of the buoy 5312.

        In that black box, at the end of july we had preponderance of green pixels (multiyear ice, at least 3 years old) . Now the black box is dominated by pink and blue pixels. And I don´t understand why.

      • intrepid_wanders says:

        Thank you diablobanquisa!

        I was not aware of this site.

        This does have the “transport mechanism” with the buoy tracks (buoys getting shoved around during compacting). Interesting data.

  3. intrepid_wanders says:

    I am with Steven on this. The boundaries show no movement, they “just fade” in their brightness or intensity. I see no transport mechanism to create the MYI melting into crushed (rafts or ridges) FYI ice. Besides, how is it that FYI is even created in the middle of the “third highest” melt season.

    I have worked with light scattering instruments and when I move the saturation (or noise) threshold up, I see the same behavior. Auto or manual saturation threshold adjustment is the most probable cause of the MYI to FYI change.

    • Julienne Stroeve says:

      Ice age is derived by following each individual ice parcel around the Arctic throughout the year. There is no threshold applied except to require the ice concentration to exceed 40%.

  4. Brendon says:

    Hmmm .. who to believe? The expert in their field with a good explanation based upon detailed observations, or Steve with his continued inability to understand based on a limited amount of data.

    • I am always overwhelmed by the intelligence behind posts like this.

      • bbttxu says:

        Haha. As far as I’ve seen Steve, you are the only one writing posts for this site, though others may write comments on your posts.

        Tell us how you really feel about yourself :p

      • Amino says:


        comments are commonly called posts

        as in, “posting comments”, “comment posted”, “I posted a comment”, “What did you post as a comment?”, “will you post a comment?”, “how many comments were posted on the site?”, “I will post a comment later”, “That was an interesting comment you posted”, “You should think more before you post on that web site”. etc.

        You were quick to laugh. My advice to you is to slow down. But I think there are people that go on the internet just to criticize. Probably not you though.

      • bbttxu says:


        No worries, emoticons are used to show that you are just having a bit of fun.

      • Brendon says:

        I am underwhelmed by the amount of posts you make …

        But I’m a quality over quantity sort of guy – no offense. 😉

  5. Julienne Stroeve says:

    Steve, another thing that can make FYI thicker than some MYI. Depending on when FYI forms, there could be significantly less snow accumulation on the ice. FYI with no snow grows thicker thanFYI with snow on top (up to 25% more) and could therefore result in FYI being thicker than MYI (especially since the MYI was thinned during the summer melt season).

  6. Pingback: Look For A Record Gain In Multi-Year Ice This Autumn | Real Science


    Walt Meier provides use an animation of the ice age from September 2009 through September 2010 (courtesy of Maslanik et al.)

    But… there is something unclear in that animation…

    – Maslanik eta al., sea ice age, week 17, 2010 (

    Maslanik et al., sea ice age, week 17, 2010, as showed in the frame used in the animation above:

    Look the changes from green (MYI) to blue (FYI and younger MYI) in the area near the Pole, north Greenland and Svalbard… ??????
    Reanalysis of the past months???

    Is that the animation that had to explain the extrange changes between the map at the end of july and at the minimum in september??????

    Something remains unclear…

  8. Sea ice age at the week 30, end of july 2010. Then ( and now (in the animation provided by Walt Meier):

    The same week, and the ice a lot younger…


  9. My question is: all this data measure sea ice. What about land ice? Apparently the magnetic north pole is shifting toward Russia, and that would lead one to believe more ice would be developing in Siberia, and away from Canada. Is there date tracking that?

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