Source code for radarx.fundamentals.reflectivity
"""
Reflectivity-Based Retrievals
=============================
Functions for reflectivity-based rainfall estimation, attenuation correction,
and reflectivity conversions. These functions are based on established
meteorological principles and are commonly used in radar meteorology.
References:
- Marshall, J. S., & Palmer, W. M. (1948). The distribution of raindrops with size. Journal of Meteorology, 5(4), 165-166.
- Bringi, V. N., & Chandrasekar, V. (2001). Polarimetric Doppler Weather Radar: Principles and Applications. Cambridge University Press.
.. autosummary::
:nosignatures:
:toctree: generated/
z_to_r_marshall_palmer
z_to_r_custom
dbz_attenuation_correction
"""
import numpy as np
[docs]
def z_to_r_marshall_palmer(dbz):
"""
Estimate rain rate [mm/hr] from reflectivity [dBZ] using Marshall-Palmer Z-R relation.
Parameters
----------
dbz : float or array-like
Reflectivity in dBZ.
Returns
-------
float or array-like
Rain rate [mm/hr]
References
----------
Marshall, J. S., & Palmer, W. M. (1948). The distribution of raindrops with size. Journal of Meteorology, 5(4), 165-166.
"""
z = 10.0 ** (0.1 * np.asarray(dbz))
return (z / 200.0) ** (1.0 / 1.6)
[docs]
def z_to_r_custom(dbz, a=200.0, b=1.6):
"""
Custom Z-R relation to estimate rain rate [mm/hr].
Parameters
----------
dbz : float or array-like
Reflectivity in dBZ.
a : float
Z-R coefficient (default: 200)
b : float
Z-R exponent (default: 1.6)
Returns
-------
float or array-like
Rain rate [mm/hr]
"""
z = 10.0 ** (0.1 * np.asarray(dbz))
return (z / a) ** (1.0 / b)
[docs]
def dbz_attenuation_correction(dbz, alpha=0.01, beta=0.85):
"""
Simple attenuation correction using a power-law fit.
Parameters
----------
dbz : float or array-like
Observed reflectivity [dBZ]
alpha : float
Attenuation coefficient scale factor (unitless)
beta : float
Attenuation exponent (unitless)
Returns
-------
float or array-like
Attenuation-corrected reflectivity [dBZ]
"""
att = alpha * (np.maximum(0, dbz) ** beta)
return dbz + att
__all__ = [
"dbz_attenuation_correction",
"z_to_r_custom",
"z_to_r_marshall_palmer",
]
