pyart.correct.dealias_unwrap_phase

pyart.correct.dealias_unwrap_phase(radar, unwrap_unit='sweep', nyquist_vel=None, check_nyquist_uniform=True, gatefilter=False, rays_wrap_around=None, keep_original=False, set_limits=True, vel_field=None, corr_vel_field=None, skip_checks=False, **kwargs)

Dealias Doppler velocities using multi-dimensional phase unwrapping [1] and [2].

Parameters:

• radar (Radar) – Radar object containing Doppler velocities to dealias.

• unwrap_unit ({‘ray’, ‘sweep’, ‘volume’}, optional) – Unit to unwrap independently. ‘ray’ will unwrap each ray individually, ‘sweep’ each sweep, and ‘volume’ will unwrap the entire volume in a single pass. ‘sweep’, the default, often gives superior results when the lower sweeps of the radar volume are contaminated by clutter. ‘ray’ does not use the gatefilter parameter and rays where gates ared masked will result in poor dealiasing for that ray.

• nyquist_velocity (array like or float, optional) – Nyquist velocity in unit identical to those stored in the radar’s velocity field, either for each sweep or a single value which will be used for all sweeps. None will attempt to determine this value from the Radar object. The Nyquist velocity of the first sweep is used for all dealiasing unless the unwrap_unit is ‘sweep’ when the velocities of each sweep are used.

• check_nyquist_uniform (bool, optional) – True to check if the Nyquist velocities are uniform for all rays within a sweep, False will skip this check. This parameter is ignored when the nyquist_velocity parameter is not None.

• gatefilter (GateFilter, None or False, optional.) – A GateFilter instance which specified which gates should be ignored when performing de-aliasing. A value of None created this filter from the radar moments using any additional arguments by passing them to moment_based_gate_filter(). False, the default, disables filtering including all gates in the dealiasing.

• rays_wrap_around (bool or None, optional) – True when the rays at the beginning of the sweep and end of the sweep should be interpreted as connected when de-aliasing (PPI scans). False if they edges should not be interpreted as connected (other scan types). None will determine the correct value from the radar scan type.

• keep_original (bool, optional) – True to retain the original Doppler velocity values at gates where the dealiasing procedure fails or was not applied. False does not replacement and these gates will be masked in the corrected velocity field.

• set_limits (bool, optional) – True to set valid_min and valid_max elements in the returned dictionary. False will not set these dictionary elements.

• vel_field (str, optional) – Field in radar to use as the Doppler velocities during dealiasing. None will use the default field name from the Py-ART configuration file.

• corr_vel_field (str, optional) – Name to use for the dealiased Doppler velocity field metadata. None will use the default field name from the Py-ART configuration file.

• skip_checks (bool) – True to skip checks verifing that an appropiate unwrap_unit is selected, False retains these checked. Setting this parameter to True is not recommended and is only offered as an option for extreme cases.

Returns:

corr_vel (dict) – Field dictionary containing dealiased Doppler velocities. Dealiased array is stored under the ‘data’ key.

References

[1]

Miguel Arevallilo Herraez, David R. Burton, Michael J. Lalor, and Munther A. Gdeisat, “Fast two-dimensional phase-unwrapping algorithm based on sorting by reliability following a noncontinuous path”, Journal Applied Optics, Vol. 41, No. 35 (2002) 7437,

[2]

Abdul-Rahman, H., Gdeisat, M., Burton, D., & Lalor, M., “Fast three-dimensional phase-unwrapping algorithm based on sorting by reliability following a non-continuous path. In W. Osten, C. Gorecki, & E. L. Novak (Eds.), Optical Metrology (2005) 32–40, International Society for Optics and Photonics.