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(warning) The last sentence above is not correct; The canonical MIR parameters are in lowercase + hyphens, always sanitized before passing in. The underscore is not a good recommendation, a space is better and an hyphen even better.

The Regrid Editor

Data input

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Input data may be specified either by giving a path in the Source parameter or by giving a GRIB-based data object in the Data parameter. Note that you should specify either Source or Data, not both.

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Drop a MARS Retrieval or a GRIB file icon inside this icon field. In Python or Macro, supply a Fieldset object.

Output grid definition

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Grid Definition Mode

Select a method for specifying the output grid.

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Code Block
languagepy
t01 = mv.regrid(
    grid     = [0.1,0.1],
    area     = [31,-17,64,38],
    data     = t_2m
    )

mv.plot(t01)


Frame

Specifies the width of a frame within a given sub-area. The width of the frame is specified as an integer number of grid points inwards from a given area. See also frame - keyword in MARS/Dissemination request.

The following plots show a sub-area with Frame=10.

Image Added

Image Added

Rotation

Position of the South Pole of the intended rotated grid as lat/lon in degree, as described here: rotation - keyword in MARS/Dissemination request.

This is applicable to regular lat/lon or regular/reduced Gaussian grids. Enter lat/lon in degree, or in Macro or Python, enter [lat, lon]; alternatively, use the  assist button to select the point graphically.

Output Lambert grid definition

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These parameters are available if Grid Definition Mode is set to Lambert Conformal or Lambert Azimuthal Equal Area. The names follow the naming convention in the descriptions of these projections here:

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Code Block
languagepy
regrid_lambert_azimuthal = mv.regrid(
    grid_definition_mode         = "lambert_azimuthal_equal_area",
    first_point                  = [50.88,-1.66],
    dx_in_metres                 = 2500,
    dy_in_metres                 = 2500,
    nx                           = 739,
    ny                           = 949,
    standard_parallel_in_degrees = 0,
    central_longitude_in_degrees = 0,
    data                         = t_2m_rgg
    )


Spectral to grid transform

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If the input files are spectral, the following parameters are used to fine-tune the conversion to grid points.

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  • Automatic: regular Gaussian grid, with N given as linear spectral order relation to output grid latitude increments
  • Source: octahedral reduced Gaussian grid, with N given as cubic spectral order relation to output grid latitude increments (mimics dissemination)
  • None: no intermediate grid, spectral inverse transform target is the user's intended output (costly if many different outputs are intended)
  • name of the desired intermediate grid

Extra processing parameters

Frame

Specifies the width of a frame within a given sub-area. The width of the frame is specified as an integer number of grid points inwards from a given area. See also frame - keyword in MARS/Dissemination request.

The following plots show a sub-area with Frame=10.

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Image Removed

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Image Removed

  • intended)
  • name of the desired intermediate grid

Wind processing

Wind Processing

Activates processing that is particular to wind fields. Possible options are:

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By default, this module will assume there are no wind fields in the input, and it will not automatically scan for pairs of U/V fields - it is up to the user to know that their input consists of wind fields and to use this setting in order to perform the correct processing.

Extra processing

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Nabla

Activates a nabla (differential) operator processing on the fields. Possible functions are:

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Available for any of the 'nearest' interpolation methods; Supports Interpolation K-Nearest Neighbours or Nearest LSM. Possible values are:

  • Distance
input points with radius (option Distance) of output point
  • Nclosest
n-closest input points (option Nclosest) to output point (default 4)
  • Distance and nclosest
input points respecting Distance ∩ Nclosest
  • Distance or nclosest
input points respecting Distance U Nclosest
  • Nclosest or nearest
n-closest input points (option Nclosest), if all are at the same distance (within option Distance Tolerance) return all points within that distance (robust interpolation of pole values)
  • Nearest neighbour with lowest index
nearest input point, if at the same distance to other points (option Nclosest) chosen by lowest index 
  • Sample
Sample of n-closest points (option Nclosest) out of input points with radius (option Distance) of output point
  • Sorted sample
as above, sorted by distance

Associated options supporting Nearest Method (described above):

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Only available if Interpolation is K Nearest Neighbours. General way on how to interpolate input neighbouring point values to output points, including the Inverse Distance Weighting (IDW) class methods (see Wikipedia), which operates over input points returned by Nearest Method. Possible values are:

  • Climate Filter
filter for processing topographic data (see IFS documentation, Part IV: Physical Processes, 11.3.1 Smoothing operator)
  • Inverse Distance Weighting
IDW of the form distance-1; If input points match output point, only that point's value is used for output
  • Inverse Distance Weighting Squared
IDW of the form (1 + distance2)-1
  • Shepard
IDW of the form distance-p (option Distance Weighting Shepard Power, default 2.)
  • Gaussian
IDW of the form exp(- distance2 / (2 σ)2) (option Distance Weighting Gaussian Stddev, default 1.)
  • Nearest Neighbour
Emulate Interpolation Nearest Neighbour by picking first point (note that, when Nearest Method is Sample, a random nearest point is picked)
  • No
no distance weighting, average input values (irrespective of distance)

On multiple input points, weights are normalised linearly to unity. Associated options supporting Distance Weighting (described above):

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For GRIB-based LSM (this excludes '1km' and '10min'), the threshold for condition (value ≥ threshold) to distinguish land (true) from sea (false).

Output GRIB

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Accuracy

Specifies the output GRIB bitsPerValue. If left empty, this will take the value from the input fields. This option can also be used to simply change the number of bits per value in a Fieldset if no other processing options are given. Note that if Packing  is set to ieee, then the only valid values for this parameter are 32 and 64.

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