pyart.filters.moment_based_gate_filter#

pyart.filters.moment_based_gate_filter(radar, ncp_field=None, rhv_field=None, refl_field=None, min_ncp=0.5, min_rhv=None, min_refl=-20.0, max_refl=100.0)[source]#

Create a filter which removes undesired gates based on moments.

Creates a gate filter in which the following gates are excluded:

  • Gates where the instrument is transitioning between sweeps.

  • Gates where the reflectivity is outside the interval min_refl, max_refl.

  • Gates where the normalized coherent power is below min_ncp.

  • Gates where the cross correlation ratio is below min_rhi. Using the default parameter this filtering is disabled.

  • Gates where any of the above three fields are masked or contain invalid values (NaNs or infs).

  • If any of these three fields do not exist in the radar that fields filter criteria is not applied.

Parameters:

  • radar (Radar) – Radar object from which the gate filter will be built.

  • refl_field, ncp_field, rhv_field (str) – Names of the radar fields which contain the reflectivity, normalized coherent power (signal quality index) and cross correlation ratio (RhoHV) from which the gate filter will be created using the above criteria. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file.

  • min_ncp, min_rhv (float) – Minimum values for the normalized coherence power and cross correlation ratio. Gates in these fields below these limits as well as gates which are masked or contain invalid values will be excluded and not used in calculation which use the filter. A value of None will disable filtering based upon the given field including removing masked or gates with an invalid value. To disable the thresholding but retain the masked and invalid filter set the parameter to a value below the lowest value in the field.

  • min_refl, max_refl (float) – Minimum and maximum values for the reflectivity. Gates outside of this interval as well as gates which are masked or contain invalid values will be excluded and not used in calculation which use this filter. A value or None for one of these parameters will disable the minimum or maximum filtering but retain the other. A value of None for both of these values will disable all filtering based upon the reflectivity including removing masked or gates with an invalid value. To disable the interval filtering but retain the masked and invalid filter set the parameters to values above and below the lowest and greatest values in the reflectivity field.

Returns:

gatefilter (GateFilter) – A gate filter based upon the described criteria. This can be used as a gatefilter parameter to various functions in pyart.correct.