Load ODIM_H5 Volume data from German Weather Service¶

In this example, we obtain and read the latest 2 hours of available volumetric radar data from German Weather Service available at opendata.dwd.de. Finally we do some plotting.

This retrieves 24 timesteps of the 10 sweeps (moments DBZH and VRADH) of the DWD volume scan of a distinct radar. This amounts to 240 data files which are combined into one volumetric Cf/Radial2 like xarray powered structure.

Exports to single file Odim_H5 and Cf/Radial2 format are shown at the end of this tutorial.

Note

The used open_odim implementation is based on netcdf4, h5py, h5netcdf and Xarray. It claims multiple data files and presents them in a simple structure. See also the notebook wradlib_odim_multi_file_dataset for further details.

[1]:

import wradlib as wrl
import warnings
warnings.filterwarnings('ignore')
import matplotlib.pyplot as pl
import numpy as np
import xarray as xr
try:
    get_ipython().magic("matplotlib inline")
except:
    pl.ion()
from wradlib.io.xarray import open_odim, CfRadial

[2]:

import urllib3
import os
import io
import glob
import shutil
import datetime
from itertools import chain

Download radar volumes of latest 2 hours from server using `wetterdienst`¶

wetterdienst is a neat package for easy retrieval of data primarily from DWD. For further information have a look at their documentation.

[3]:

from wetterdienst.dwd.radar import DWDRadarData, DWDRadarParameter, DWDRadarDate, DWDRadarDataFormat, DWDRadarDataSubset
from wetterdienst.dwd.radar.sites import DWDRadarSite

[4]:

start_date = datetime.datetime.utcnow()

# Horizontal Doppler Velocity
request_velocity = DWDRadarData(
    parameter=DWDRadarParameter.SWEEP_VOL_VELOCITY_H,
    start_date=start_date - datetime.timedelta(hours=2),
    end_date=start_date,
    site=DWDRadarSite.ESS,
    fmt=DWDRadarDataFormat.HDF5,
    subset=DWDRadarDataSubset.POLARIMETRIC,
)

# Horizontal Reflectivity
request_reflectivity = DWDRadarData(
    parameter=DWDRadarParameter.SWEEP_VOL_REFLECTIVITY_H,
    start_date=start_date - datetime.timedelta(hours=2),
    end_date=start_date,
    site=DWDRadarSite.ESS,fmt=DWDRadarDataFormat.HDF5,
    subset=DWDRadarDataSubset.POLARIMETRIC,
)

# Submit requests.
results = chain(request_velocity.collect_data(), request_reflectivity.collect_data())

Acquire data as memory buffer¶

[5]:

# Collect in-memory data
files = []
for item in results:
    files.append(item.data)

Read the data into xarray powered structure¶

[6]:

# Decode data using wradlib.
vol = wrl.io.open_odim(files)

Open: 100%|██████████| 485/485 [00:00<00:00, 520.55 Files/s]
Collecting: 100%|██████████| 10/10 [00:00<00:00, 133.23 Angles/s]

Plot Quasi Vertical Profile¶

[21]:

vol

[21]:

<wradlib.XRadVolume>
Dimension(s): (sweep: 10)
Elevation(s): (5.5, 4.5, 3.5, 2.5, 1.5, 0.5, 8.0, 12.0, 17.0, 25.0)

[22]:

ts = vol[-1]
ts

[22]:

<wradlib.XRadTimeSeries>
Dimension(s): (time: 24, azimuth: 360, range: 60)
Elevation(s): (25.0)

[23]:

fig = pl.figure(figsize=(10, 4))
ax = fig.add_subplot(111)
ts.data.DBZH.median('azimuth').plot(x='time', vmin=-10, vmax=30, ax=ax)
ax.set_title(f"{np.datetime_as_string(ts.data.time[0].values, unit='D')}")
ax.set_ylim(0, 20000)

[23]:

(0.0, 20000.0)

Export to OdimH5¶

This exports the radar volume at given timestep including all moments into one ODIM_H5 compliant data file.

[24]:

vol.to_odim('dwd_odim.h5', timestep=0)

Export to Cf/Radial2¶

This exports the radar volume at given timestep including all moments into one Cf/Radial2 compliant data file.

[25]:

vol.to_cfradial2('dwd_cfradial2.nc', timestep=0)

Import again and check equality¶

Small time differences are possible so drop times before comparison

[26]:

try:
    vol1 = open_odim('dwd_odim.h5')
    vol2 = CfRadial('dwd_cfradial2.nc', dim0='azimuth')
    xr.testing.assert_equal(vol1.root, vol2.root)
    xr.testing.assert_equal(vol1[1][0].data.drop('time').rename({'rtime': 'time'}), vol2['sweep_1'])
    print("Equality Check successful")
except:
    print("Equality Check not successful")

Open: 100%|██████████| 1/1 [00:00<00:00, 51.36 Files/s]
Collecting: 100%|██████████| 10/10 [00:00<00:00, 2144.33 Angles/s]

Equality Check not successful

Load ODIM_H5 Volume data from German Weather Service¶

Download radar volumes of latest 2 hours from server using `wetterdienst`¶

Acquire data as memory buffer¶

Read the data into xarray powered structure¶

Inspect structure¶

Root Group¶

Sweep Groups¶

plot sweeps¶

DBZH¶

VRADH¶

Plot single sweep using cartopy¶

Inspect radar moments¶

Plot Quasi Vertical Profile¶

Export to OdimH5¶

Export to Cf/Radial2¶

Import again and check equality¶

Load ODIM_H5 Volume data from German Weather Service¶

Download radar volumes of latest 2 hours from server using wetterdienst¶

Acquire data as memory buffer¶

Read the data into xarray powered structure¶

Inspect structure¶

Root Group¶

Sweep Groups¶

plot sweeps¶

DBZH¶

VRADH¶

Plot single sweep using cartopy¶

Inspect radar moments¶

Plot Quasi Vertical Profile¶

Export to OdimH5¶

Export to Cf/Radial2¶

Import again and check equality¶

Download radar volumes of latest 2 hours from server using `wetterdienst`¶