From: Dennis Shea (shea AT XXXXXX)
Date: Mon Jan 27 2003 - 09:45:26 MST

  • Next message: Mary Haley: "New capabilities in reading GRIB files with NCL"

    >I am trying to read JMA forecast files in GRIB format with NCL.
    >The number of longitudinal grids reduced toward the poles
    >thus grids are not rectilinear.
    >These files do not follow NCL's convection and
    >does not provide gridx and gridy.
    >Longitude grid arrays are problematic as below.
    >Is there anything I can do in the script?
    >Otherwise I will preprocess the files with other tools.

    Hello Takeshi,

    The new version of NCL [a028] will handle these GRIB
    "quasi-regular" grids (ie: reduced grids). It autonatically
    unpacks the grid into 1.25 x 1.25 degree grids.

    The "lat_37" and "lon_37" variables will look like:

    printVarSummary (lon_37)

    Variable: lon_37
    Type: float
    Total Size: 292 bytes
                73 values
    Number of Dimensions: 1
    Dimensions and sizes: [lon_37 | 73]
                lon_37: [-30..60]
    Number Of Attributes: 8
      GridType : Cylindrical Equidistant Projection Grid (Quasi-Regular)
      units : degrees_east
      Dj : 1.25
      Di : 1.25
      Lo2 : 60
      La2 : 90
      Lo1 : -30
      La1 : 0

    ncl 5> printVarSummary (lat_37) 

    Variable: lat_37 Type: float Total Size: 292 bytes 73 values Number of Dimensions: 1 Dimensions and sizes: [lat_37 | 73] Coordinates: lat_37: [ 0..90] Number Of Attributes: 8 GridType : Cylindrical Equidistant Projection Grid (Quasi-Regular) units : degrees_north Dj : 1.25 Di : 1.25 Lo2 : 60 La2 : 90 Lo1 : -30 La1 : 0 ----

    Fot those interested, more information on these resuced grids is available at:

    If you are interested in helping us to beta test these new capabilities, please send email to Mary Haley [ haley AT ] and let her know what kind of system you have. She will send you more information about these new capabilities and a binary to try.

    Regards Dennis Shea

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