uvwind

../../_images/DIVROT.png

Computes the wind from spectral (shperical harmonics) divergence and vorticity GRIB fields.

Note

This function performs the same task as the Rotational or Divergent Wind icon in Metview’s user interface. It accepts its parameters as keyword arguments, described below.

uvwind(**kwargs)

Computes the wind from spectral (spherical harmonics) divergence and vorticity GRIB fields.

Parameters

  • data (Fieldset) – Specifies the divergence and vorticity GRIB fields. Must be spectral (spherical harmonics) data.

  • divergence_param (number, default: 155) – Specifies the ecCodes paramId that identifies the divergence in data. New in Metview version 5.13.0.

  • vorticity_param (number, default: 138) – Specifies the ecCodes paramId that identifies the vorticity in data. New in Metview version 5.13.0.

  • truncation (number, default: 216) – Specifies the triangular truncation to be applied to the spherical harmonics input data prior to conversion to lat/lon.

  • smoothing ({"yes", "no"}, default: "no") –

    Specifies whether to apply spatial smoothing to the spherical harmonics prior to transformation to grid points. This operation is performed after the truncation specified in truncation. The smoothing filter is of the form:

    \[exp^{(-\frac {n(n+1)}{fltc(fltc+1)})^{mfltexp}}\]

    where:

    • n: is the wavenumber

    • fltc, mfltexp: see below

    This is roughly equivalent to a \(\nabla^{2 \times mfltexp}\) operator in grid point space.

  • fltc (number, default: 19.4) – Specifies the value of the parameter fltc to be used in the smoothing filter. Only available if smoothing set to “yes”.

  • mfltexp (number, default: 2) – Specifies the value of the parameter mfltexp to be used in the smoothing filter. Only available if smoothing is set to “yes”. The default value is 2, roughly equivalent to a \(\nabla^{4}\) operator in grid point space.

Return type

Fieldset