Comparison of Antarctic and Arctic Single-Layer Stratiform Mixed-Phase Cloud Properties Using Ground-Based Remote Sensing Measurements

Ground-based remote sensing measurements from the Atmospheric Radiation Measurement Program (ARM) West Antarctic Radiation Experiment (AWARE) campaign at the McMurdo station and the ARM North Slope of Alaska (NSA) Utqiaġvik site are used to retrieve and analyze single-layer stratiform mixed-phase cloud macrophysical and microphysical properties for these different polar environments. Single-layer stratiform mixed-phase clouds have annual frequencies of occurrence of ~14.7% at Utqiaġvik and ~7.3% at McMurdo, with the highest occurrences in early autumn. Compared to Utqiaġvik, stratiform mixed-phase clouds at McMurdo have overall higher and colder cloud-tops, thicker ice layer depth, thinner liquid-dominated layer depth, and smaller liquid water path. These properties show clear seasonal variations. Supercooled liquid fraction at McMurdo is greater than at Utqiaġvik because, at a given temperature, McMurdo clouds have comparable liquid water paths but smaller ice water paths. Analyses of retrieved cloud microphysical properties show that compared to Utqiaġvik, stratiform mixed-phase clouds at McMurdo have greater liquid droplet number concentration, smaller layer-mean effective radius, and smaller ice water content and ice number concentration at a given cloud-top temperature. These relationships may be related to different aerosol loading and chemical composition, and environment dynamics. Results presented in this study can be used as observational constraints for model representations of stratiform mixed-phase clouds.