Investigating Microphysics Timestep and Multi-Microphysics Intercomparisons in Arctic Stratiform Mixed-Phase Clouds during MOSAiC

Accurately representing microphysical processes in numerical weather models is challenging due to the complexity from varying hydrometeor shape, size, and phase, which cannot be explicitly resolved. This challenge is compounded by the difficulty of directly observing these quantities. Field campaigns, like the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), are well-suited for enhancing our understanding of these complex cloud physics processes unique to the Arctic due to the availability of comprehensive high resolution observational datasets for verification. This case is one of many being used to engage with physics developers in assessing physics innovations for the Unified Forecast System (UFS) research and development.

One focus of the MOSAiC campaign was to observe Arctic mixed-phase clouds and the interaction between cloud, radiation, and microphysical processes. For this purpose, a mixed-phase stratiform cloud case spanning 31 October to 5 November 2019 was used to investigate the distribution of various cloud phases through a multi-microphysics intercomparison using the Common Community Physics Package (CCPP) Single Column Model (SCM). In addition, testing was conducted to investigate microphysics performance across scales, and to identify an optimal microphysics time step for a given grid spacing. Results from these intercomparisons among multiple microphysics and microphysics timestep evaluation using the CCPP SCM will be presented.