"""Towerpy: an open-source toolbox for processing polarimetric radar data."""
import datetime as dt
from zoneinfo import ZoneInfo
import numpy as np
from ..georad import georef_rdata as geo
[docs]
class Rad_scan:
"""
A Towerpy class to store radar scan data.
Attributes
----------
elev_angle : float
Elevation angle at which the scan was taken, in deg.
file_name : str
Name of the file containing radar data.
scandatetime : datetime
Date and time of scan.
site_name : str
Name of the radar site.
georef : dict
Georeferenced data containing descriptors of the azimuth, gates
and beam height, amongst others.
params : dict
Radar technical details.
vars : dict
Radar variables.
"""
def __init__(self, filename, site_name=None):
[docs]
self.file_name = filename
[docs]
self.site_name = site_name
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def ppi_emptylike(self, nrays=360, ngates=425, elev=0.5,
rad_vars='default', scandt=None, tz='Europe/London'):
r"""
Create an empty object listing different radar parameters.
Parameters
----------
nrays : int
Number of rays on the radar sweep. The default is 360.
ngates : int, optional
Number of bins comprising the radar rays. The default is 425.
elev : float, optional
Elevation angle of the radar scan. The default is 0.5.
rad_vars : list, optional
Polarimetric variables to add to the object. The default are:
:math:`Z_{H} [dBZ]`, :math:`Z_{DR} [dB]`,
:math:`\rho_{HV} [-]`, :math:`\Phi_{DP} [deg]`, :math:`V [m/s]`
The default is 'default'.
scandt : datetime, optional
Date and time of the scan. If not provided, datetime.now is used.
The default is None.
tz : str
Key/name of the radar data timezone. The given tz string is then
retrieved from the ZoneInfo module. Default is 'Europe/London'
"""
# add aditional pol vars defined by the user
if rad_vars == 'default':
radvars = ['ZH [dBZ]', 'ZDR [dB]', 'PhiDP [deg]', 'rhoHV [-]',
'V [m/s]']
else:
radvars = rad_vars
# create dicts to store the empty arrays
# poldata = {i: np.empty([nrays, ngates],dtype=float) for i in radvars}
poldata = {i: np.nan for i in radvars}
parameters = {'nvars': len(radvars), 'ngates': int(ngates),
'nrays': int(nrays), 'gateres [m]': np.nan,
'rpm': np.nan, 'prf [Hz]': np.nan,
'pulselength [ns]': np.nan, 'avsamples': np.nan,
'wavelength [cm]': np.nan,
'latitude [dd]': np.nan, 'longitude [dd]': np.nan,
'altitude [m]': 0, 'easting [km]': np.nan,
'northing [km]': np.nan, 'radar constant [dB]': 0,
'elev_ang [deg]': elev,
'beamwidth [deg]': 1.}
if scandt is None:
parameters['datetime'] = dt.datetime.now(tz=ZoneInfo(tz))
nowdt = [dt.datetime.now(tz=ZoneInfo(tz)).year,
dt.datetime.now(tz=ZoneInfo(tz)).month,
dt.datetime.now(tz=ZoneInfo(tz)).day,
dt.datetime.now(tz=ZoneInfo(tz)).hour,
dt.datetime.now(tz=ZoneInfo(tz)).minute,
dt.datetime.now(tz=ZoneInfo(tz)).second]
parameters['datetimearray'] = nowdt
else:
parameters['datetime'] = scandt.replace(tzinfo=ZoneInfo(tz))
udt = list(parameters['datetime'].timetuple())[: -3]
parameters['datetimearray'] = udt
self.vars = poldata
self.params = parameters
self.elev_angle = parameters['elev_ang [deg]']
self.scandatetime = parameters['datetime']
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def ppi_create_georef(self, polarc_exist=True, elev=0.5, gate0=0,
gateres=250):
"""
Create a georeferenced grid for the empty object.
Parameters
----------
polarc_exist : bool
If True, polar coordinates (range, azimuth, elevation) are
read directly from the georef attribute. If False,
synthesise elevation, azimuth, and range.
The default is True
elev : float
Elevation angle in degrees (used if `polarc_exist=False`).
The default is 0.5
gate0 : float
Starting range gate in metres (used if `polarc_exist=False`).
The default is 0
gateres : float
Gate resolution in metres (used if `polarc_exist=False`).
The default is 250
Notes
-----
1. Polar coordinates (azimuth, elevation) are expected to be in radians, and range values are expected to be in metres.
2. Some radar technical details are read from Rad_scan.params
3. This method wraps :func:`geo.ppi_georef` and updates the object's `georef` attribute with computed Cartesian grids and beam heights.
"""
if polarc_exist:
geogrid, _ = geo.ppi_georef(self.params, georef=self.georef)
else:
geogrid, geopolc = geo.ppi_georef(
self.params, polarc_exist=False, elev=elev, gate0=gate0,
gateres=gateres)
# Update resolution in params
self.params['gateres [m]'] = gateres
if hasattr(self, 'georef'):
self.georef.update(geogrid)
else:
self.georef = {'azim [rad]': geopolc['azim [rad]'],
'elev [rad]': geopolc['elev [rad]'],
'range [m]': geopolc['range [m]']}
self.georef.update(geogrid)
