pyart.correct.calculate_attenuation_zphi#

pyart.correct.calculate_attenuation_zphi(radar, doc=None, fzl=None, smooth_window_len=5, gatefilter=None, a_coef=None, beta=None, c=None, d=None, refl_field=None, phidp_field=None, zdr_field=None, temp_field=None, iso0_field=None, spec_at_field=None, pia_field=None, corr_refl_field=None, spec_diff_at_field=None, pida_field=None, corr_zdr_field=None, temp_ref='temperature')[source]#

Calculate the attenuation and the differential attenuation from a polarimetric radar using Z-PHI method.. The attenuation is computed up to a user defined freezing level height or up to where temperatures in a temperature field are positive. The coefficients are either user-defined or radar frequency dependent.

NOTE: The base 10 forumulation that uses attenuated radar reflectivity and differential phase that is used in this function can be found in Gu et al (2011).

Parameters:

  • radar (Radar) – Radar object to use for attenuation calculations. Must have phidp and refl fields.

  • doc (float, optional) – Number of gates at the end of each ray to to remove from the calculation.

  • fzl (float, optional) – Freezing layer, gates above this point are not included in the correction.

  • gatefilter (GateFilter, optional) – The gates to exclude from the calculation. This, combined with the gates above fzl, will be excluded from the correction. Set to None to not use a gatefilter.

  • smooth_window_len (int, optional) – Size, in range bins, of the smoothing window

  • a_coef (float, optional) – A coefficient in attenuation calculation.

  • beta (float, optional) – Beta parameter in attenuation calculation.

  • c, d (float, optional) – coefficient and exponent of the power law that relates attenuation with differential attenuation

  • refl_field (str, optional) – Name of the reflectivity field used for the attenuation correction. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file.

  • phidp_field (str, optional) – Name of the differential phase field used for the attenuation correction. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file.

  • zdr_field (str, optional) – Name of the differential reflectivity field used for the attenuation correction. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file. This will only be used if it is available.

  • temp_field (str, optional) – Name of the temperature field used for the attenuation correction. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file.

  • iso0_field (str, optional) – Name of the field for the height above the 0C isotherm for the attenuation correction. A value of None for any of these parameters will use the default field name as defined in the Py-ART configuration file. This will only be used if it is available.

  • spec_at_field (str, optional) – Name of the specific attenuation field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file.

  • pia_field (str, optional) – Name of the path integrated attenuation field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file.

  • corr_refl_field (str, optional) – Name of the corrected reflectivity field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file.

  • spec_diff_at_field (str, optional) – Name of the specific differential attenuation field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file. This will only be calculated if ZDR is available.

  • pida_field (str, optional) – Name of the path integrated differential attenuation field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file. This will only be calculated if ZDR is available.

  • corr_zdr_field (str, optional) – Name of the corrected differential reflectivity field that will be used to fill in the metadata for the returned fields. A value of None for any of these parameters will use the default field names as defined in the Py-ART configuration file. This will only be calculated if ZDR is available.

  • temp_ref (str, optional) – the field use as reference for temperature. Can be either temperature, height_over_iso0 or fixed_fzl

Returns:

  • spec_at (dict) – Field dictionary containing the specific attenuation.

  • pia_dict (dict) – Field dictionary containing the path integrated attenuation.

  • cor_z (dict) – Field dictionary containing the corrected reflectivity.

  • spec_diff_at (dict) – Field dictionary containing the specific differential attenuation.

  • pida_dict (dict) – Field dictionary containing the path integrated differential attenuation.

  • cor_zdr (dict) – Field dictionary containing the corrected differential reflectivity.

References

Gu et al. Polarimetric Attenuation Correction in Heavy Rain at C Band, JAMC, 2011, 50, 39-58.

Ryzhkov et al. Potential Utilization of Specific Attenuation for Rainfall Estimation, Mitigation of Partial Beam Blockage, and Radar Networking, JAOT, 2014, 31, 599-619.