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pyart.retrieve.gecsx#

pyart.retrieve.gecsx(radar, radar_specs, dem_grid, fill_value=None, terrain_altitude_field=None, bent_terrain_altitude_field=None, terrain_slope_field=None, terrain_aspect_field=None, elevation_angle_field=None, visibility_field=None, min_vis_elevation_field=None, min_vis_altitude_field=None, incident_angle_field=None, effective_area_field=None, sigma_0_field=None, rcs_clutter_field=None, dBm_clutter_field=None, dBZ_clutter_field=None, visibility_polar_field=None, az_conv=0, dr=100, daz=0.012, ke=1.3333333333333333, atm_att=0.2, mosotti_kw=0.9644, raster_oversampling=1, sigma0_method='Gabella', clip=True, return_pyart_objects=True, verbose=True)[source]#

Estimate the radar visibility and ground clutter echoes from a digital elevation model

Parameters:

  • radar (radar) – Radar object which contains the coordinates on which the visibility will be computed

  • radar_specs (dict) – Dictionary containing the radar specifications. Must have the following keys:

    “frequency” : radar frequenty in GHz “tau” : radar pulsewidth in m “beamwidth” : antenna 3dB beamwidth in deg “loss” : total loss (antenna + radar system) in dB “gain” : total gain (antenna + radar system) in dB “power” : radar total power in W

  • terrain_altitude_field (str, optional) – Field name which represents the terrain altitude class field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • bent_terrain_altitude_field (str, optional) – Field name which represents the terrain altitude after radar refractivity height correction class field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • terrain_slope_field (str, optional) – Field name which represents the terrain slope class field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • terrain_aspect_field (str, optional) – Field name which represents the terrain aspect class field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • elevation_angle_field (str, optional) – Field name which represents the elevation angle class field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • visibility_field (str, optional) – Field name which represents the Cartesian visibility field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • min_vis_elevation_field (str, optional) – Field name which represents the minimum visible elevation angle field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • min_vis_altitude_field (str, optional) – Field name which represents the minimum visible altitude field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • sigma_0_field (str, optional) – Field name which represents the ratio between rcs and backscattering area field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • incident_angle_field (str, optional) – Field name which represents the incidence angle at the topography field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • effective_area_field (str, optional) – Field name which represents the effective backscattering area. A value of None will use the default field name as defined in the Py-ART configuration file.

  • rcs_clutter_field (str, optional) – Field name which represents the backscattering cross section. A value of None will use the default field name as defined in the Py-ART configuration file.

  • dBm_clutter_field (str, optional) – Field name which represents the ground clutter power signal field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • dBZ_clutter_field (str, optional) – Field name which represents the ground clutter reflectivity field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • visibility_polar_field (str, optional) – Field name which represents the polar visibility field. A value of None will use the default field name as defined in the Py-ART configuration file.

  • az_conv (float, optional) – If larger than zero assumes that the antenna moves in azimuth direction (PPI) and averages the rx signal over the angle given by this keyword

  • dr (float, optional) – Range discretization used when computing the Cartesian visibility field the larger the better but the slower the processing will be

  • daz (float, optional) – Azimuth discretization used when computing the Cartesian visibility field, the larger the better but the slower the processing will be

  • ke (float(optional)) – Equivalent earth-radius factor used in the computation of the radar beam refraction

  • atm_att (float, optional) – One-way atmospheric refraction in db / km

  • mosotti_kw (float, optional) – Clausius-Mosotti factor K, depends on material (water) and wavelength for water = sqrt(0.93)

  • raster_oversampling (int, optional) – The raster resolution of the DEM should be smaller than the range resolution of the radar (defined by the pulse length). If this is not the case, this keyword can be set to increase the raster resolution. The values for the elevation, sigma naught, visibility are repeated. The other values are recalculated. Values for raster_oversampling: 0 or undefined: No oversampling is done 1: Oversampling is done. The factor N is automatically calculated such that 2*dx/N < pulse length 2 or larger: Oversampling is done with this value as N

  • sigma0_method (string, optional) – Which estimation method to use, either ‘Gabella’ or ‘Delrieu’

  • clip (bool, optional) – If set to true, the provided DEM will be clipped to the extent of the polar radar domain. Increases computation speed a lot but Cartesian output fields will be available only over radar domain

  • return_pyart_objects (bool, optional) – If set to true, the generated products will be directly added to the input DEM Grid object (for Cartesian products) and the input Radar object (for polar products). Otherwise all products will be output separately

  • verbose (bool, optional) – If set to true, the program will display info about the current progress

Returns:

  • bent_terrain_altitude_dic (dict) – Terrain altitude corrected for radar beam height data and metadata

  • terrain_slope_dic (dict) – Terrain slope data and metadata

  • terrain_aspect_dic, (dict) – Terrain aspect data and metadata

  • elevation_dic, (dict) – Elevation angle at topography data and metadata

  • min_vis_elevation_dic, (dict) – Minimum visible elevation data and metadata

  • min_vis_altitude_dic, (dict) – Minimum visible altitude data and metadata

  • visibility_dic, (dict) – Visibility over a Cartesian domain data and metadata

  • incident_angle_dic, (dict) – Incidence angle at topography data and metadata

  • effective_area_dic, (dict) – Effective backscattering area data and metadata

  • sigma_0_dic, (dict) – Ratio between RCS and backscattering area data and metadata

  • rcs_clutter_dic, (dict) – Radar cross-section data and metadata

  • dBm_clutter_dic, (dict) – Ground clutter power data and metadata

  • dBZ_clutter_dic, (dict) – Ground clutter reflectivity data and metadata

  • visibility_polar_dic, (dict) – Visibility over the polar radar domain data and metadata

References

Gabella, M., & Perona, G. (1998). Simulation of the Orographic Influence on Weather Radar Using a Geometric–Optics Approach, Journal of Atmospheric and Oceanic Technology, 15(6), 1485-1494.

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