wradlib.atten.specific_attenuation_zphi

wradlib.atten.specific_attenuation_zphi#

wradlib.atten.specific_attenuation_zphi(phidp, dbz, alpha, b, rng=2000.0)[source]#

Estimate specific attenuation (\(A_H\) or \(A_V\)) using the ZPHI method.

This implementation follows the ZPHI approach ([Testud et al., 2000], [Ryzhkov et al., 2014], [Diederich et al., 2015]), where the total differential phase shift (\(\Delta \Phi_{DP}\)) is first estimated from a representative range interval, and then used to constrain the attenuation–reflectivity relationship.

Parameters:

  • phidp (xarray.DataArray) – Differential phase field with a range dimension.

  • dbz (xarray.DataArray) – Reflectivity field in decibels (dBZ), same range dimension as phidp.

  • alpha (float or array-like) – ZPHI coefficient(s) controlling the relationship between phase shift and attenuation.

  • b (float) – Exponent in the ZPHI power-law formulation.

  • rng (float, optional) – Physical range (m) used for estimating total differential phase shift. Default is 2000 m.

Returns:

xarray.DataArray – Specific attenuation field with metadata attributes:

  • units: dB/km

  • standard_name: specific_attenuation_h or v

  • long_name: human-readable description

  • short_name: AH or AV

Notes

  • Uses delta_phidp to estimate total differential phase shift.

  • Negative phase shifts are clamped to a small positive value for stability.

  • Reflectivity is converted from dBZ to linear units before integration.

  • Assumes identical range coordinate system for phidp and dbz.

Examples

See Core Features - Attenuation - Specific Attenuation via ZPHI method.