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HOME > Monitoring_and_Data > Oceanic and Atmospheric Data > Reanalysis: Atmospheric Data > wgrib2-new_grid_ipipt

wgrib2: -new_grid_ipopt


The -new_grid option interpolates from one grid into another. The -new_grid_interpolation option selects the interpolation method. The -new_grid_ipopt option modifies the parameters used by the interpolation method. The -new_grid_ipopt option MUST FOLLOW the -new_grid_interpolation option because the latter will overwrite the IPOPT values with the default values for that interpolation method.

  1. bilinear: ipopt is not used
  2. bicubic:
    1. ipopt(1) = 0: straight bicubic
    2. ipopt(1) = 1: constrained to range of 4 neighboring points
    3. ipopt(2) = %data converage for output point, default=50%
  3. nearest neighbor: ipopt is not used
  4. budget: ipopt is not used
  5. spectral: (alpha)
    1. ipopt(1) = 0: triangular truncation
    2. ipopt(1) = 1: rhomboidal truncation
    3. ipopt(2) = N: truncation number
    4. ipopt(2) = -1: sensible truncation number, based on grid (default for now, will be changed)
        note: should specify these values by -new_grid_interpolation
        when ipopt(2) == -1, sensible trunction number
                IROMB = ipopt(1)
                IDRT=4 FOR GAUSSIAN GRID
                IF(IROMB.EQ.0.AND.IDRTI.EQ.4) MAXWV=(JMAXI-1)
                IF(IROMB.EQ.1.AND.IDRTI.EQ.4) MAXWV=(JMAXI-1)/2
                IF(IROMB.EQ.0.AND.IDRTI.EQ.0) MAXWV=(JMAXI-3)/2
                IF(IROMB.EQ.1.AND.IDRTI.EQ.0) MAXWV=(JMAXI-3)/4
                IF(IROMB.EQ.0.AND.IDRTI.EQ.256) MAXWV=(JMAXI-1)/2
                IF(IROMB.EQ.1.AND.IDRTI.EQ.256) MAXWV=(JMAXI-1)/4
        Note: The values are appropriate for the spectral GFS Gaussian grid
              because the grid values were derived from the spherical harmonics.
              The values are not appropriate for the FV3 GFS Gaussian grid
              because the grid values were derived by a bilinear interpolation
              (mostly) from the cubed sphere grid.
              Since NCEP is transitioning to a FV3 model, the grid point values
              are not the exact representation of the model fields but rather
              a bilinear interpolation from the cubed sphere.  So a high-wavenumber
              noise is being added to the grid values.  So the appropriate spectral
              representation will have filter applied to the spectral represenation.
              The math hasn't been worked out.
  6. neighbor-budget: not enabled by wgrib2


-new_grid_ipopt X
    X = integer or integer:integer
See also: -new_grid, -new_grid_winds -new_grid_vectors new_grid usage -if -fi

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Page last modified: Sept 18, 2017
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