Evaluation of convective cloud microphysics in numerical weather prediction models with dual-wavelength polarimetric radar observations: methods and examples
<p>The representation of cloud microphysical processes contributes substantially to the uncertainty of numerical weather simulations. In part, this is owed to some fundamental knowledge gaps in the underlying processes due to the difficulty of observing them directly. On the path to closing th...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/15/1033/2022/amt-15-1033-2022.pdf |
| Summary: | <p>The representation of cloud microphysical processes contributes substantially
to the uncertainty of numerical weather simulations. In part, this is owed to
some fundamental knowledge gaps in the underlying processes due to the
difficulty of observing them directly. On the path to closing these gaps, we present
a setup for the systematic characterization of differences between numerical
weather model and radar observations for convective weather situations. Radar
observations are introduced which provide targeted dual-wavelength and
polarimetric measurements of convective clouds with the potential to provide
more detailed information about hydrometeor shapes and sizes. A convection-permitting regional weather model setup is established using five different
microphysics schemes (double-moment, spectral bin (“Fast Spectral Bin
Microphysics”, FSBM), and particle property
prediction (P3)). Observations are compared to hindcasts which are created with
a polarimetric radar forward simulator for all measurement days. A
cell-tracking algorithm applied to radar and model data facilitates comparison
on a
cell object basis. Statistical comparisons of radar observations and numerical
weather model runs are presented on a data set of 30 convection days. In
general, simulations show too few weak and small-scale convective cells.
Contoured frequency by altitude diagrams of radar signatures reveal deviations
between the schemes and observations in ice and liquid phase. Apart from the P3
scheme, high reflectivities in the ice phase are simulated too frequently.
Dual-wavelength
signatures demonstrate issues of most schemes to correctly represent ice
particle size distributions, producing too large or too dense graupel particles.
Comparison of polarimetric radar signatures reveals issues of all schemes except
the FSBM to correctly represent rain particle size distributions.</p> |
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| ISSN: | 1867-1381 1867-8548 |