Potential of mm-Wave Doppler-Polarimetric Profiler Observations for Quality Assessment of Hydrometeor Classification Schemes

Journal Article (2025)
Author(s)

Linda Bogerd (Wageningen University & Research, Royal Netherlands Meteorological Institute (KNMI))

H. Leijnse (Royal Netherlands Meteorological Institute (KNMI))

Aart Overeem (TU Delft - Water Systems Monitoring & Modelling, Royal Netherlands Meteorological Institute (KNMI))

Christine M. H. Unal (TU Delft - Atmospheric Remote Sensing)

Remko Uijlenhoet (TU Delft - Water Systems Monitoring & Modelling)

S. van der Veen (Royal Netherlands Meteorological Institute (KNMI))

Research Group
Water Systems Monitoring & Modelling
DOI related publication
https://doi.org/10.1029/2024JD042398
More Info
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Publication Year
2025
Language
English
Research Group
Water Systems Monitoring & Modelling
Issue number
11
Volume number
130
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Abstract

Dual-polarization weather radars have improved the accuracy of precipitation estimates. However, challenges persist in evaluating hydrometeor classification (HMC) algorithms, thereby impacting the accuracy of precipitation estimates. This study proposes to use full Doppler spectra in both polarizations from a Ka- and W-band Doppler-polarimetric profiler with a 45° elevation angle to provide insights into hydrometeor characteristics. A novel methodology was developed to link the observed spectra with the output of an HMC scheme. We applied the wradlib HMC scheme using C-band weather radar data from the Netherlands for six cases (2021–2022). The HMC scheme output is used to calculate mixing ratios that are combined with the corresponding scattering properties using the Atmospheric Radiative Transfer Simulator microwave single scattering properties database (frozen hydrometeors) and T-matrix calculations (liquid hydrometeors) to simulate Doppler spectra of polarimetric variables that would be measured by the profiler. Comparing these simulations with actual profiler measurements enables a quality assessment. The method works in stratiform cases, but convective cases reveal the influence of turbulence and wind variability. Uncertainty arises from the selection of specific parameterizations for the particle size distribution and the relationship between hydrometeor size and terminal fall velocity as well as from the derived mixing ratios. Additionally, the 45° angle complicates separating horizontal wind from hydrometeor fall velocities, although the Mie notch in the dual-wavelength ratio can be effectively used to remove the radial wind component. Our results underline limitations that must be addressed but also show that integrating spectral and dual-frequency observations could yield valuable insights into hydrometeor characteristics.