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This icon interpolates irregularly spaced point data (in Geopoints format) into a GRIB field, which can then be plotted, saved or combined with other GRIB data. The method used to compute the values of the grid points from the input data depends on the Interpolation Method parameter. The resulting GRIB field can be a regular lat/lon grid of defined size, or else based on a template GRIB file supplied by the user. Note that only the first parameter of a double-valued geopoints vector will be used in the calculations.

For the reverse computation, see Grib To Geopoints.The macro language equivalent is

Info

From Macro/Python this icon can be called as geo_to_grib()



The Geopoints To GRIB Editor

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Specifies the input data, which must be in Geopoints format (e.g. a geopoints data icon or an Observation Filter icon returning geopoints).

The Bufr Picker Editor

Data

Drop any icon containing or returning BUFR data. This may be, for example, a MARS Retrieval (of observations) icon, a BUFR file icon or an Observation Filter icon (provided it outputs BUFR, not geopoints).

Grib Definition Mode

If set to User, the output grid will be a regular lat/lon matrix defined by the parameters Area and Grid; if set to Grib, an example GRIB file should be specified by the parameter Template Grib.

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  • Reciprocal: the mean of the values, weighted by the inverse of their distance from the target point. If one of the geopoints lies exactly on the target point then its value is used directly and the rest of the values discarded.

  • Exponential Mean: computes the mean of the values weighted (multiplied) by the following:

    • if Tolerance is not zero:

      Mathinline
      e^{-distance/tolerance^2}


    • if Tolerance is zero: 1 if the point is on the target point, 0 otherwise
    • note that this method, combined with setting Tolerance to zero computes the proportion of points which lie exactly on the target point
  • Exponential Sum: performs the same computation as Exponential Mean, but does not finally divide by the total weight. With a Tolerance of zero, this method will compute the number of input points that lie exactly on each target point.
  • Nearest Gridpoint Mean: for each target grid point, computes the unweighted mean value of the geopoints for whom this is the closest grid point; any grid point which is not the closest to any geopoints will be given a missing value
  • Nearest Gridpoint Sum: for each target grid point, computes the unweighted sum of the values of the geopoints for whom this is the closest grid point; any grid point which is not the closest to any geopoints will be given a missing value
  • Nearest Gridpoint Count:  for each target grid point, computes the number of geopoints for whom this is the closest grid point. Note that for a regular target grid, this essentially produces a 'heat map', where the value of a grid point will be the number of geopoints within its grid box. This is not necessarily true for quasi-regular grids, e.g. reduced Gaussian, reduced lat/lon or octahedral (which is just a specific type of reduced Gaussian).

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