Within AFWA's 4-km resolution ensemble WRF-ARW output, the only supercooled water information available is within the cloud droplet and rain drop fields. Through previous evaluation of the cloud droplet size distribution assumptions made within each of several single-moment microphysics schemes, empirical relations were established between cloud droplet diameter and mixing ratio. This information was then used to predict the location and amount of small and large supercooled water drops, and by extension, location and severity of glaze and rime ice. In this study, this method is extended to the full suite of microphysics schemes used with the AFWA ensemble, including double-moment schemes. Effects of explicitly perturbing cloud condensation nuclei and cloud droplet concentrations are examined, particularly in the context of the droplet spectra broadening required to produce freezing drizzle.
Predicted glaze and rime ice fields are evaluated using dual-polarized radar, pilot reports, and observations from the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) field campaign.