# Data Transformation#

Module <trafo> transforms data e.g. from RVP-units to dBZ-values to Z-values and vice versa.

 rvp_to_dbz Calculates dBZ-values from DWD RVP6 values as given in DX-product files. decibel Calculates the decibel representation of the input values idecibel Calculates the inverse of input decibel values r_to_depth Computes rainfall depth (mm) from rainfall intensity (mm/h) kdp_to_r Estimating rainfall intensity directly from specific differential phase. si_to_kmh Conversion from SI wind speed units to km/hr. si_to_mph Conversion from SI wind speed units to miles/hr si_to_kts Conversion from SI wind speed units to knots kmh_to_si Conversion from km/hr to SI wind speed units mph_to_si Conversion from miles/hr to SI wind speed units kts_to_si Conversion from knots to SI wind speed units KuBandToS Class to hold coefficients for Radar Reflectivity Conversion KuBandToX Class to hold coefficients for Radar Reflectivity Conversion SBandToKu Class to hold coefficients for Radar Reflectivity Conversion TrafoMethods wradlib xarray SubAccessor methods for DualPol.

Calculates dBZ-values from DWD RVP6 values as given in DX-product files.

Parameters

x (float or numpy.ndarray) – a number or an array

Examples

>>> from wradlib.trafo import rvp_to_dbz
>>> print(rvp_to_dbz(65.))
0.0


Calculates the decibel representation of the input values

$$dBZ=10 \cdot \log_{10} z$$

Parameters

x (float or numpy.ndarray) – (must not be <= 0.)

Examples

>>> from wradlib.trafo import decibel
>>> print(decibel(100.))
20.0


Calculates the inverse of input decibel values

$$z=10^{x \over 10}$$

Parameters

Examples

>>> from wradlib.trafo import idecibel
>>> print(idecibel(10.))
10.0


Computes rainfall depth (mm) from rainfall intensity (mm/h)

Parameters
Returns

output (float or numpy.ndarray) – rainfall depth (mm)

Estimating rainfall intensity directly from specific differential phase.

The general power law expression has been suggested by .

The default parameters have been set according to .

Note

Please note that this way, rainfall intensities can become negative. This is an intended behaviour in order to account for noisy $$K_{DP}$$ values.

Parameters
Returns

output (numpy.ndarray) – array of rainfall intensity

Conversion from SI wind speed units to km/hr.

Note

Parameters

vals (float or numpy.ndarray) – Speed in SI units (m/s)

Returns

output (float or numpy.ndarray) – Speed in km/hr

Examples

>>> from wradlib.trafo import si_to_kmh
>>> print(si_to_kmh(1.))
3.6


Conversion from SI wind speed units to miles/hr

Note

Parameters

vals (float or numpy.ndarray) – Speed in SI units (m/s)

Returns

output (float or numpy.ndarray) – Speed in miles per hour

Examples

>>> from wradlib.trafo import si_to_mph
>>> print(np.round(si_to_mph(1.), 3))
2.237


Conversion from SI wind speed units to knots

Note

Parameters

vals (float or numpy.ndarray) – Speed in SI units (m/s)

Returns

output (float or numpy.ndarray) – Speed in knots

Examples

>>> from wradlib.trafo import si_to_kts
>>> print(np.round(si_to_kts(1.), 3))
1.944


Conversion from km/hr to SI wind speed units

Note

Parameters

vals (float or numpy.ndarray) – Wind speed in km/hr

Returns

output (float or numpy.ndarray) – Wind speed in SI units (m/s)

Examples

>>> from wradlib.trafo import kmh_to_si
>>> print(np.round(kmh_to_si(10.), 3))
2.778


Conversion from miles/hr to SI wind speed units

Note

Parameters

vals (float or numpy.ndarray) – Wind speed in miles per hour

Returns

output (float or numpy.ndarray) – Wind speed in SI units (m/s)

Examples

>>> from wradlib.trafo import mph_to_si
>>> print(np.round(mph_to_si(10.), 2))
4.47


Conversion from knots to SI wind speed units

Note

Parameters

vals (float or numpy.ndarray) – Wind speed in knots

Returns

output (float or numpy.ndarray) – Wind speed in SI units (m/s)

Examples

>>> from wradlib.trafo import kts_to_si
>>> print(np.round(kts_to_si(1.), 3))
0.514


Bases: object

Class to hold coefficients for Radar Reflectivity Conversion

From Ku-band (13.8 GHz) to S-band (2.8 GHz)

See for reference.

snow = array([[ 4.78e-02,  4.12e-02,  8.12e-02,  1.59e-01,  2.87e-01,  4.93e-01,          8.16e-01,  1.31e+00,  2.01e+00,  2.82e+00,  1.74e-01],        [ 1.23e-02,  3.66e-03,  2.00e-03,  9.42e-04,  5.29e-04,  5.96e-04,          1.22e-03,  2.11e-03,  3.34e-03,  5.33e-03,  1.35e-02],        [-3.50e-04,  1.17e-03,  1.04e-03,  8.16e-04,  6.59e-04,  5.85e-04,          6.13e-04,  7.01e-04,  8.24e-04,  1.01e-03, -1.38e-03],        [-3.30e-05, -8.08e-05, -6.44e-05, -4.97e-05, -4.15e-05, -3.89e-05,         -4.15e-05, -4.58e-05, -5.06e-05, -5.78e-05,  4.74e-05],        [ 4.27e-07,  9.25e-07,  7.41e-07,  6.13e-07,  5.80e-07,  6.16e-07,          7.12e-07,  8.22e-07,  9.39e-07,  1.10e-06,  0.00e+00]])#
hail = array([[ 4.78e-02,  1.80e-01,  1.95e-01,  1.88e-01,  2.36e-01,  2.70e-01,          2.98e-01,  2.85e-01,  1.75e-01,  4.30e-02,  8.80e-02],        [ 1.23e-02, -3.73e-02, -3.83e-02, -3.29e-02, -3.46e-02, -2.94e-02,         -2.10e-02, -9.96e-03, -8.05e-03, -8.27e-03,  5.39e-02],        [-3.50e-04,  4.08e-03,  4.14e-03,  3.75e-03,  3.71e-03,  3.22e-03,          2.44e-03,  1.45e-03,  1.21e-03,  1.66e-03, -2.99e-04],        [-3.30e-05, -1.59e-04, -1.54e-04, -1.39e-04, -1.30e-04, -1.12e-04,         -8.56e-05, -5.33e-05, -4.66e-05, -7.19e-05,  1.90e-05],        [ 4.27e-07,  1.59e-06,  1.51e-06,  1.37e-06,  1.29e-06,  1.15e-06,          9.40e-07,  6.71e-07,  6.33e-07,  9.52e-07,  0.00e+00]])#

Bases: object

Class to hold coefficients for Radar Reflectivity Conversion

From Ku-band (13.8 GHz) to X-band (9.4 GHz)

See for reference.

snow = array([[ 1.91e-01, -1.20e-01],        [-7.83e-02,  6.80e-02],        [ 1.12e-02, -4.55e-03],        [-6.17e-04,  1.18e-04],        [ 1.25e-05, -6.60e-07],        [-8.43e-08,  0.00e+00]])#
hail = array([[ 1.91e-01,  5.57e-02],        [-7.83e-02,  1.80e-02],        [ 1.12e-02,  1.91e-03],        [-6.17e-04, -6.64e-05],        [ 1.25e-05,  8.18e-07],        [-8.43e-08,  0.00e+00]])#

Bases: object

Class to hold coefficients for Radar Reflectivity Conversion

From S-band (2.8GHz) to Ku-band (13.8GHz)

See for reference.

snow = array([ 0.185074  ,  1.01378   , -0.00189212])#
rain = array([-1.50393e+00,  1.07274e+00,  1.65393e-04])#

Bases: XarrayMethods

wradlib xarray SubAccessor methods for DualPol.

decibel()[source]#

Calculates the decibel representation of the input values

$$dBZ=10 \cdot \log_{10} z$$

Parameters

x (float or numpy.ndarray) – (must not be <= 0.)

Examples

>>> from wradlib.trafo import decibel
>>> print(decibel(100.))
20.0

idecibel()[source]#

Calculates the inverse of input decibel values

$$z=10^{x \over 10}$$

Parameters

Examples

>>> from wradlib.trafo import idecibel
>>> print(idecibel(10.))
10.0

r_to_depth(interval)[source]#

Computes rainfall depth (mm) from rainfall intensity (mm/h)

Parameters
Returns

output (float or numpy.ndarray) – rainfall depth (mm)