Quick-view a sweep in polar coordinates

import numpy as np
import matplotlib.pyplot as plt
import wradlib as wrl
import wradlib_data
import warnings
import xarray as xr
import cmweather

warnings.filterwarnings("ignore")
try:
    get_ipython().run_line_magic("matplotlib inline")
except:
    plt.ion()

/home/docs/checkouts/readthedocs.org/user_builds/wradlib/conda/stable/lib/python3.13/site-packages/tqdm/auto.py:21: TqdmWarning: IProgress not found. Please update jupyter and ipywidgets. See https://ipywidgets.readthedocs.io/en/stable/user_install.html
  from .autonotebook import tqdm as notebook_tqdm

Read a polar data set in ODIM_H5 from the Koninklijk Nederlands Meteorologisch Instituut (KNMI)

filename = wradlib_data.DATASETS.fetch("hdf5/knmi_polar_volume.h5")
print(filename)

Downloading file 'hdf5/knmi_polar_volume.h5' from 'https://github.com/wradlib/wradlib-data/raw/main/data/hdf5/knmi_polar_volume.h5' to '/home/docs/.cache/wradlib-data'.

/home/docs/.cache/wradlib-data/hdf5/knmi_polar_volume.h5

swp = xr.open_dataset(filename, engine="odim", group="sweep_0")

Inspect the data set a little

display(swp)

<xarray.Dataset> Size: 468kB
Dimensions:            (azimuth: 360, range: 320)
Coordinates:
  * azimuth            (azimuth) float32 1kB 0.5 1.5 2.5 ... 357.5 358.5 359.5
    elevation          (azimuth) float32 1kB ...
    time               (azimuth) datetime64[ns] 3kB ...
  * range              (range) float32 1kB 500.0 1.5e+03 ... 3.185e+05 3.195e+05
    longitude          float32 4B ...
    latitude           float32 4B ...
    altitude           float32 4B ...
Data variables:
    DBZH               (azimuth, range) float32 461kB ...
    sweep_mode         <U20 80B ...
    sweep_number       int64 8B ...
    prt_mode           <U7 28B ...
    follow_mode        <U7 28B ...
    sweep_fixed_angle  float32 4B ...
    nyquist_velocity   object 8B ...
Attributes:
    Conventions:  ODIM_H5/V2_2

xarray.Dataset

• Dimensions:
  • azimuth: 360
  • range: 320
• Coordinates: (7)
  • azimuth
    (azimuth)
    float32
    0.5 1.5 2.5 ... 357.5 358.5 359.5

    standard_name :

    ray_azimuth_angle

    long_name :

    azimuth_angle_from_true_north

    units :

    degrees

    axis :

    radial_azimuth_coordinate

    array([  0.5,   1.5,   2.5, ..., 357.5, 358.5, 359.5],
          shape=(360,), dtype=float32)

  • elevation
    (azimuth)
    float32
    ...

    standard_name :

    ray_elevation_angle

    long_name :

    elevation_angle_from_horizontal_plane

    units :

    degrees

    axis :

    radial_elevation_coordinate

    [360 values with dtype=float32]

  • time
    (azimuth)
    datetime64[ns]
    ...

    standard_name :

    time

    [360 values with dtype=datetime64[ns]]

  • range
    (range)
    float32
    500.0 1.5e+03 ... 3.195e+05

    units :

    meters

    standard_name :

    projection_range_coordinate

    long_name :

    range_to_measurement_volume

    axis :

    radial_range_coordinate

    meters_between_gates :

    1000.0

    spacing_is_constant :

    true

    meters_to_center_of_first_gate :

    500.0

    array([   500.,   1500.,   2500., ..., 317500., 318500., 319500.],
          shape=(320,), dtype=float32)

  • longitude
    ()
    float32
    ...

    long_name :

    longitude

    units :

    degrees_east

    standard_name :

    longitude

    [1 values with dtype=float32]

  • latitude
    ()
    float32
    ...

    long_name :

    latitude

    units :

    degrees_north

    positive :

    up

    standard_name :

    latitude

    [1 values with dtype=float32]

  • altitude
    ()
    float32
    ...

    long_name :

    altitude

    units :

    meters

    standard_name :

    altitude

    [1 values with dtype=float32]

• Data variables: (7)
  • DBZH
    (azimuth, range)
    float32
    ...

    _Undetect :

    0.0

    units :

    dBZ

    standard_name :

    radar_equivalent_reflectivity_factor_h

    long_name :

    Equivalent reflectivity factor H

    [115200 values with dtype=float32]

  • sweep_mode
    ()
    <U20
    ...

    [1 values with dtype=<U20]

  • sweep_number
    ()
    int64
    ...

    [1 values with dtype=int64]

  • prt_mode
    ()
    <U7
    ...

    [1 values with dtype=<U7]

  • follow_mode
    ()
    <U7
    ...

    [1 values with dtype=<U7]

  • sweep_fixed_angle
    ()
    float32
    ...

    [1 values with dtype=float32]

  • nyquist_velocity
    ()
    object
    ...

    standard_name :

    nyquist_velocity

    units :

    m s-1

    [1 values with dtype=object]

• Attributes: (1)

  Conventions :

  ODIM_H5/V2_2

The simplest plot

swp = swp.wrl.georef.georeference()
swp = swp.set_coords("sweep_mode")
pm = swp.DBZH.wrl.vis.plot()
txt = plt.title("Simple PPI")