towerpy.calib.calib_zdr

Towerpy: an open-source toolbox for processing polarimetric radar data.

Classes

ZDR_Calibration

A class to calibrate the radar differential reflectivity.

Module Contents

class towerpy.calib.calib_zdr.ZDR_Calibration(radobj=None)

A class to calibrate the radar differential reflectivity.

Attributes

elev_anglefloat

Elevation angle at where the scan was taken, in degrees.

file_namestr

Name of the file containing radar data.

scandatetimedatetime

Date and time of scan.

site_namestr

Name of the radar site.

zdr_offsetdict

Computed \(Z_{DR}\) offset

zdr_offset_statsdict

Stats calculated during the computation of the \(Z_{DR}\) offset.

varsdict

Offset-corrected \((Z_{DR})\) and user-defined radar variables.

elev_angle = None

file_name = None

scandatetime = None

site_name = None

offsetdetection_vps(pol_profs, mlyr=None, min_h=1.1, zhmin=5, zhmax=30, rhvmin=0.98, minbins=2, stats=False, plot_method=False, rad_georef=None, rad_vars=None)

Calculate the offset on \(Z_{DR}\) using vertical profiles.

Parameters

pol_profsdict

Profiles of polarimetric variables.

mlyrclass

Melting layer class containing the top and bottom boundaries of the ML. Only gates below the melting layer bottom (i.e. the rain region below the melting layer) are included in the method. If None, the default values of the melting level and the thickness of the melting layer are set to 5 and 0.5, respectively.

min_hfloat, optional

Minimum height of usable data within the polarimetric profiles. The default is 1.1.

zhminfloat, optional

Threshold on \(Z_{H}\) (in dBZ) related to light rain. The default is 5.

zhmaxfloat, optional

Threshold on \(Z_{H}\) (in dBZ) related to light rain. The default is 30.

rhvminfloat, optional

Threshold on \(\rho_{HV}\) (unitless) related to light rain. The default is 0.98.

minbinsfloat, optional

Consecutive bins of \(Z_{DR}\) related to light rain. The default is 2.

statsdict, optional

If True, the function returns stats related to the computation of the \(Z_{DR}\) offset. The default is False.

plot_methodBool, optional

Plot the offset detection method. The default is False.

rad_georefdict, optional

Used only to depict the methodolgy. Georeferenced data containing descriptors of the azimuth, gate and beam height, amongst others. The default is None.

rad_varsdict, optional

Used only to depict the methodolgy. Radar variables used for plotting the offset correction method. The default is None.

Notes

1. Based on the method described in [1]_ and [2]

References

[1]

Gorgucci, E., Scarchilli, G., and Chandrasekar, V. (1999), A procedure to calibrate multiparameter weather radar using properties of the rain medium, IEEE T. Geosci. Remote, 37, 269–276, https://doi.org/10.1109/36.739161

[2]

Sanchez-Rivas, D. and Rico-Ramirez, M. A. (2022): “Calibration of radar differential reflectivity using quasi-vertical profiles”, Atmos. Meas. Tech., 15, 503–520, https://doi.org/10.5194/amt-15-503-2022

offsetdetection_qvps(pol_profs, mlyr=None, min_h=0.0, max_h=3.0, zhmin=0, zhmax=20, rhvmin=0.985, minbins=4, zdr_0=0.182, stats=False)

Calculate the offset on \(Z_{DR}\) using QVPs, acoording to [1]_.

Parameters

pol_profsdict

Profiles of polarimetric variables.

mlyrclass

Melting layer class containing the top and bottom boundaries of the ML.

min_hfloat, optional

Minimum height of usable data within the polarimetric profiles. The default is 0.

max_hfloat, optional

Maximum height of usable data within the polarimetric profiles. The default is 3.

zhminfloat, optional

Threshold on \(Z_{H}\) (in dBZ) related to light rain. The default is 0.

zhmaxfloat, optional

Threshold on \(Z_{H}\) (in dBZ) related to light rain. The default is 20.

rhvminfloat, optional

Threshold on \(\rho_{HV}\) (unitless) related to light rain. The default is 0.985.

minbinsfloat, optional

Consecutive bins of \(Z_{DR}\) related to light rain. The default is 3.

zdr_0float, optional

Intrinsic value of \(Z_{DR}\) in light rain at ground level. Defaults to 0.182.

statsdict, optional

If True, the function returns stats related to the computation of the \(Z_{DR}\) offset. The default is False.

Notes

1. Based on the method described in [1]

References

[1]

Sanchez-Rivas, D. and Rico-Ramirez, M. A. (2022): “Calibration of radar differential reflectivity using quasi-vertical profiles”, Atmos. Meas. Tech., 15, 503–520, https://doi.org/10.5194/amt-15-503-2022

offset_correction(zdr2calib, zdr_offset=0, data2correct=None)

Correct the ZDR offset using a given value.

Parameters

zdr2calibarray of float

Offset-affected differential reflectiviy \(Z_{DR}\) in dB.

zdr_offsetfloat

Differential reflectivity offset in dB. The default is 0.

data2correctdict, optional

Dictionary to update the offset-corrected \(Z_{DR}\). The default is None.