New insights into convection-permitting model simulations from a ZDR diagnostic for raindrops

Lo, C. H. B. ORCID: https://orcid.org/0000-0001-7661-7080, Stein, T. H. M. ORCID: https://orcid.org/0000-0002-9215-5397, Westbrook, C. D. ORCID: https://orcid.org/0000-0002-2889-8815, Field, P. R., Furtado, K., Scovell, R. W., Wilkinson, J. M., Darlington, T., Lean, H. W., Neely III, R. R. and Walden, C. J. (2026) New insights into convection-permitting model simulations from a ZDR diagnostic for raindrops. Quarterly Journal of the Royal Meteorological Society. e70237. ISSN 1477-870X doi: 10.1002/qj.70237

Abstract/Summary

A polarimetric radar forward operator to simulate differential reflectivity (ZDR) from rain was developed to evaluate storms in the Met Office Unified Model (MetUM). Sub-kilometre simulations were carried out for two case days of the Wessex Convection Experiment (WesCon) field campaign in summer of 2023. The joint distribution of reflectivity (ZH) and ZDR followed a one-to-one relationship for simulations using a single-moment microphysics scheme, in contrast with radar observations. Simulations using the CASIM double-moment microphysics scheme reproduced a spread in ZDR values for a given reflectivity similar to observations. Vertical columns of ZDR, indicative of strong updrafts, were overly intense and high in the single-moment simulations compared to the observations, whereas ZDR column heights and intensities in the double-moment simulations were more comparable to observations. Vertical velocities did not vary much between the different model configurations, suggesting differences in mass distributions for different hydrometeor types. ZDR from prognostic rain can thus reveal model biases and provides new avenues for future model evaluation and development.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/131252
Identification Number/DOI	10.1002/qj.70237
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Royal Meteorological Society
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