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    Gfs upgrade v16.3

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    • J
      jamalas1 last edited by

      Good evening everyone
      It is known that there is a gfs update with v16.3 with an accuracy of 0.25 and a horizontal accuracy of 13 km on 29/11/2022. Is there an update on the gfs maps in windy as it is now with an accuracy of 22 km as the site mentions?

      idefix37 1 Reply Last reply Reply Quote 0
      • idefix37
        idefix37 Sailor Moderator @jamalas1 last edited by idefix37

        @jamalas1
        Hi, afaik GFS v16 is computed at a 13km resolution but displayed for each with 23km resolution. You say 0.25°, a quarter of 1° which is 111km. It is therefore not less than 23km. Nothing is changed for horizontal resolution and GFS was always been computed at 13km but displayed at 23km.
        What has been improved is the vertical resolution.

        Gkikas LGPZ 1 Reply Last reply Reply Quote 0
        • Referenced by  idefix37 idefix37 
        • Gkikas LGPZ
          Gkikas LGPZ Moderator @idefix37 last edited by

          @idefix37
          O.25° = 0.25x60nm = 15 nm =27.8 km

          idefix37 2 Replies Last reply Reply Quote 0
          • idefix37
            idefix37 Sailor Moderator @Gkikas LGPZ last edited by idefix37

            @Gkikas-LGPZ
            Yes Mate, you are right or in another way
            1° = 111.1km
            0.25° = 1°/4 = 111.1 / 4 = 27.8km
            which is not 13km as said above.

            1 Reply Last reply Reply Quote 0
            • idefix37
              idefix37 Sailor Moderator @Gkikas LGPZ last edited by idefix37

              @Gkikas-LGPZ
              Then, the question is why does Windy say the GFS resolution is 22km, not 27km?
              The NOAA gives the resolution as measured on the parallel of Washington (39°N) which is about the parallel in the middle of USA. But parallels are not great circles.
              0.25° measured on this parallel is not 27km, it is 22km as shown by this sketch.

              D3D335EF-6926-4C33-8BA4-90AB7DDEDF56.jpeg

              This way of specifying the resolution of a global model seems to be a sort of standard now. The ECMWF center says that its model (IFS) has a resolution of 0.1° or 9km. It is obviously measured also on 39° parallel (which is not however in the middle of Europe).

              BEC3311F-349C-4E5F-846A-BBDCE2D91A8C.jpeg

              Hope my sketches are clear.

              1 Reply Last reply Reply Quote 2
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