xarray ODIM backend¶
In this example, we read ODIM_H5 (HDF5) data files using the xarray odim
backend.
[1]:
import glob
import os
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 import open_odim_dataset
Load ODIM_H5 Volume Data¶
[2]:
fpath = 'hdf5/knmi_polar_volume.h5'
f = wrl.util.get_wradlib_data_file(fpath)
vol = wrl.io.open_odim_dataset(f)
Inspect RadarVolume¶
[3]:
display(vol)
<wradlib.RadarVolume>
Dimension(s): (sweep: 14)
Elevation(s): (0.3, 0.4, 0.8, 1.1, 2.0, 3.0, 4.5, 6.0, 8.0, 10.0, 12.0, 15.0, 20.0, 25.0)
Inspect root group¶
The sweep
dimension contains the number of scans in this radar volume. Further the dataset consists of variables (location coordinates, time_coverage) and attributes (Conventions, metadata).
[4]:
vol.root
[4]:
<xarray.Dataset> Dimensions: (sweep: 14) Coordinates: time datetime64[ns] 2011-06-10T11:40:02 sweep_mode <U20 'azimuth_surveillance' longitude float64 4.79 altitude float64 50.0 latitude float64 52.95 Dimensions without coordinates: sweep Data variables: volume_number int64 0 platform_type <U5 'fixed' instrument_type <U5 'radar' primary_axis <U6 'axis_z' time_coverage_start <U20 '2011-06-10T11:40:02Z' time_coverage_end <U20 '2011-06-10T11:43:54Z' sweep_group_name (sweep) <U8 'sweep_0' 'sweep_1' ... 'sweep_13' sweep_fixed_angle (sweep) float64 0.3 0.4 0.8 1.1 ... 12.0 15.0 20.0 25.0 Attributes: version: None title: None institution: None references: None source: None history: None comment: im/exported using wradlib instrument_name: None fixed_angle: 0.30000001192092896
Inspect sweep group(s)¶
The sweep-groups can be accessed via their respective keys. The dimensions consist of range
and time
with added coordinates azimuth
, elevation
, range
and time
. There will be variables like radar moments (DBZH etc.) and sweep-dependend metadata (like fixed_angle
, sweep_mode
etc.).
[5]:
display(vol[0])
<xarray.Dataset> Dimensions: (azimuth: 360, range: 320) Coordinates: * azimuth (azimuth) float32 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 elevation (azimuth) float32 0.3 0.3 0.3 0.3 0.3 ... 0.3 0.3 0.3 0.3 0.3 rtime (azimuth) datetime64[ns] 2011-06-10T11:40:17.361118208 ... 20... * range (range) float32 500.0 1.5e+03 2.5e+03 ... 3.185e+05 3.195e+05 time datetime64[ns] 2011-06-10T11:40:02 sweep_mode <U20 'azimuth_surveillance' longitude float64 4.79 latitude float64 52.95 altitude float64 50.0 Data variables: DBZH (azimuth, range) float32 ... Attributes: fixed_angle: 0.30000001192092896
Goereferencing¶
[6]:
swp = vol[0].copy().pipe(wrl.georef.georeference_dataset)
Plotting¶
[7]:
swp.DBZH.plot.pcolormesh(x='x', y='y')
pl.gca().set_aspect('equal')
[8]:
fig = pl.figure(figsize=(10,10))
swp.DBZH.wradlib.plot_ppi(proj='cg', fig=fig)
[8]:
<matplotlib.collections.QuadMesh at 0x7f859c526b90>
[9]:
import cartopy
import cartopy.crs as ccrs
import cartopy.feature as cfeature
map_trans = ccrs.AzimuthalEquidistant(central_latitude=swp.latitude.values,
central_longitude=swp.longitude.values)
[10]:
map_proj = ccrs.AzimuthalEquidistant(central_latitude=swp.latitude.values,
central_longitude=swp.longitude.values)
pm = swp.DBZH.wradlib.plot_ppi(proj=map_proj)
ax = pl.gca()
ax.gridlines(crs=map_proj)
print(ax)
< GeoAxes: +proj=aeqd +ellps=WGS84 +lon_0=4.7899699211120605 +lat_0=52.953338623046875 +x_0=0.0 +y_0=0.0 +no_defs +type=crs >
[11]:
map_proj = ccrs.Mercator(central_longitude=swp.longitude.values)
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, projection=map_proj)
pm = swp.DBZH.wradlib.plot_ppi(ax=ax)
ax.gridlines(draw_labels=True)
[11]:
<cartopy.mpl.gridliner.Gridliner at 0x7f8598ded900>
[12]:
import cartopy.feature as cfeature
def plot_borders(ax):
borders = cfeature.NaturalEarthFeature(category='physical',
name='coastline',
scale='10m',
facecolor='none')
ax.add_feature(borders, edgecolor='black', lw=2, zorder=4)
map_proj = ccrs.Mercator(central_longitude=swp.longitude.values)
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, projection=map_proj)
DBZH = swp.DBZH
pm = DBZH.where(DBZH > 0).wradlib.plot_ppi(ax=ax)
plot_borders(ax)
ax.gridlines(draw_labels=True)
[12]:
<cartopy.mpl.gridliner.Gridliner at 0x7f8598e63fd0>
[13]:
import matplotlib.path as mpath
theta = np.linspace(0, 2*np.pi, 100)
center, radius = [0.5, 0.5], 0.5
verts = np.vstack([np.sin(theta), np.cos(theta)]).T
circle = mpath.Path(verts * radius + center)
map_proj = ccrs.AzimuthalEquidistant(central_latitude=swp.latitude.values,
central_longitude=swp.longitude.values,
)
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, projection=map_proj)
ax.set_boundary(circle, transform=ax.transAxes)
pm = swp.DBZH.wradlib.plot_ppi(proj=map_proj, ax=ax)
ax = pl.gca()
ax.gridlines(crs=map_proj)
[13]:
<cartopy.mpl.gridliner.Gridliner at 0x7f859c3cd270>
[14]:
fig = pl.figure(figsize=(10, 8))
proj=ccrs.AzimuthalEquidistant(central_latitude=swp.latitude.values,
central_longitude=swp.longitude.values)
ax = fig.add_subplot(111, projection=proj)
pm = swp.DBZH.wradlib.plot_ppi(ax=ax)
ax.gridlines()
[14]:
<cartopy.mpl.gridliner.Gridliner at 0x7f85a47c0430>
[15]:
swp.DBZH.wradlib.plot_ppi()
[15]:
<matplotlib.collections.QuadMesh at 0x7f85a474d780>
Inspect radar moments¶
The DataArrays can be accessed by key or by attribute. Each DataArray has dimensions and coordinates of it’s parent dataset. There are attributes connected which are defined by ODIM_H5 standard.
[16]:
display(swp.DBZH)
<xarray.DataArray 'DBZH' (azimuth: 360, range: 320)> array([[ 22. , 17. , -8. , ..., -31.5, -31.5, -31.5], [ 24. , 24.5, -9. , ..., -31.5, -31.5, -31.5], [ 35.5, 42. , 12. , ..., -31.5, -31.5, -31.5], ..., [ 23. , 14. , -13. , ..., -31.5, -31.5, -31.5], [ 23. , 14. , -9. , ..., -31.5, -31.5, -31.5], [ 22. , 18.5, -11.5, ..., -31.5, -31.5, -31.5]], dtype=float32) Coordinates: (12/15) * azimuth (azimuth) float32 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 elevation (azimuth) float32 0.3 0.3 0.3 0.3 0.3 ... 0.3 0.3 0.3 0.3 0.3 rtime (azimuth) datetime64[ns] 2011-06-10T11:40:17.361118208 ... 20... * range (range) float32 500.0 1.5e+03 2.5e+03 ... 3.185e+05 3.195e+05 time datetime64[ns] 2011-06-10T11:40:02 sweep_mode <U20 'azimuth_surveillance' ... ... x (azimuth, range) float32 4.363 13.09 ... -2.777e+03 -2.786e+03 y (azimuth, range) float32 500.0 1.5e+03 ... 3.183e+05 3.193e+05 z (azimuth, range) float32 53.0 58.0 64.0 ... 7.691e+03 7.734e+03 gr (azimuth, range) float32 500.0 1.5e+03 ... 3.183e+05 3.193e+05 rays (azimuth, range) float32 0.5 0.5 0.5 0.5 ... 359.5 359.5 359.5 bins (azimuth, range) float32 500.0 1.5e+03 ... 3.185e+05 3.195e+05 Attributes: _Undetect: 0.0 standard_name: radar_equivalent_reflectivity_factor_h long_name: Equivalent reflectivity factor H units: dBZ
Create simple plot¶
Using xarray features a simple plot can be created like this. Note the sortby('rtime')
method, which sorts the radials by time.
[17]:
swp.DBZH.sortby('rtime').plot(x="range", y="rtime", add_labels=False)
[17]:
<matplotlib.collections.QuadMesh at 0x7f8598b88eb0>
[18]:
fig = pl.figure(figsize=(5,5))
pm = swp.DBZH.wradlib.plot_ppi(proj={'latmin': 33e3}, fig=fig)
Mask some values¶
[19]:
swp['DBZH'] = swp['DBZH'].where(swp['DBZH'] >= 0)
swp['DBZH'].plot()
[19]:
<matplotlib.collections.QuadMesh at 0x7f859c284490>
Export to ODIM and CfRadial2¶
[20]:
vol.to_odim('knmi_odim.h5')
vol.to_cfradial2('knmi_odim_as_cfradial.nc')
Import again¶
[21]:
vola = wrl.io.open_odim_dataset('knmi_odim.h5')
[22]:
volb = wrl.io.open_cfradial2_dataset('knmi_odim_as_cfradial.nc')
Check equality¶
[23]:
xr.testing.assert_allclose(vol.root, vola.root)
xr.testing.assert_equal(vol[0], vola[0])
xr.testing.assert_allclose(vol.root, volb.root)
xr.testing.assert_equal(vol[0], volb[0])
xr.testing.assert_allclose(vola.root, volb.root)
xr.testing.assert_equal(vola[0], volb[0])
More ODIM loading mechanisms¶
Use xr.open_dataset
to retrieve explicit group¶
[24]:
swp = xr.open_dataset(f, engine="odim", group="dataset14")
display(swp)
<xarray.Dataset> Dimensions: (azimuth: 360, range: 240) Coordinates: * azimuth (azimuth) float32 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 elevation (azimuth) float32 25.0 25.0 25.0 25.0 ... 25.0 25.0 25.0 25.0 rtime (azimuth) datetime64[ns] 2011-06-10T11:43:48.763874560 ... 20... * range (range) float32 250.0 750.0 1.25e+03 ... 1.192e+05 1.198e+05 time datetime64[ns] 2011-06-10T11:43:45 sweep_mode <U20 'azimuth_surveillance' longitude float64 4.79 latitude float64 52.95 altitude float64 50.0 Data variables: DBZH (azimuth, range) float32 -31.5 -0.5 0.0 ... -31.5 -31.5 -31.5 Attributes: fixed_angle: 25.0
Use xr.open_mfdataset
to retrieve timeseries of explicit group¶
[25]:
fpath = os.path.join(wrl.util.get_wradlib_data_path(), "hdf5/71*.h5")
f = glob.glob(fpath)
ts = xr.open_mfdataset(f, engine="odim", concat_dim="time", combine="nested", group="dataset1")
display(ts)
<xarray.Dataset> Dimensions: (time: 2, azimuth: 360, range: 1200) Coordinates: * azimuth (azimuth) float32 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 elevation (azimuth) float32 dask.array<chunksize=(360,), meta=np.ndarray> rtime (time, azimuth) datetime64[ns] 2018-12-20T06:12:41.009703424 ... * range (range) float32 125.0 375.0 625.0 ... 2.996e+05 2.999e+05 * time (time) datetime64[ns] 2018-12-20T06:12:28 2018-12-20T06:06:28 sweep_mode <U20 'azimuth_surveillance' longitude float64 151.2 latitude float64 -33.7 altitude float64 195.0 Data variables: DBZH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> DBZH_CLEAN (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> VRADDH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> VRADH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> WRADH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> TH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> ZDR (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> RHOHV (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> PHIDP (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> KDP (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> SNRH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> Attributes: fixed_angle: 0.5
Use wrl.io.open_odim_mfdataset
to retrieve volume timeseries¶
[26]:
fpath = os.path.join(wrl.util.get_wradlib_data_path(), "hdf5/71*.h5")
f = glob.glob(fpath)
ts = wrl.io.open_odim_mfdataset(f)
display(ts)
100%|██████████| 14/14 [00:02<00:00, 5.38it/s]
<wradlib.RadarVolume>
Dimension(s): (sweep: 14)
Elevation(s): (0.5, 0.9, 1.3, 1.8, 2.4, 3.1, 4.2, 5.6, 7.4, 10.0, 13.3, 17.9, 23.9, 32.0)
[27]:
display(ts[0])
<xarray.Dataset> Dimensions: (time: 2, azimuth: 360, range: 1200) Coordinates: * azimuth (azimuth) float32 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 elevation (azimuth) float32 dask.array<chunksize=(360,), meta=np.ndarray> rtime (time, azimuth) datetime64[ns] 2018-12-20T06:12:41.009703424 ... * range (range) float32 125.0 375.0 625.0 ... 2.996e+05 2.999e+05 * time (time) datetime64[ns] 2018-12-20T06:12:28 2018-12-20T06:06:28 sweep_mode <U20 'azimuth_surveillance' longitude float64 151.2 latitude float64 -33.7 altitude float64 195.0 Data variables: DBZH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> DBZH_CLEAN (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> VRADDH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> VRADH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> WRADH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> TH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> ZDR (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> RHOHV (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> PHIDP (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> KDP (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> SNRH (time, azimuth, range) float32 dask.array<chunksize=(1, 360, 1200), meta=np.ndarray> Attributes: fixed_angle: 0.5