Southern Ocean Low Cloud and Precipitation Phase Observed During the Macquarie Island Cloud and Radiation Experiment (MICRE)

A significant portion of low clouds over Macquarie Island, particularly those with cold tops (≤0°C), exhibit predominantly liquid-phase characteristics at cloud base, despite the potential for mixed or ice-phase precipitation below. This study, conducted during the Macquarie Island Cloud and Radiation Experiment (MICRE) from April 2016 to March 2017, found that around two-thirds of low clouds were cold-topped, with these clouds being thicker and having higher bases compared to warm-topped clouds. The research utilized ground-based ceilometer, depolarization lidar, and W-band radar measurements to characterize cloud macrophysics and precipitation phase. Notably, 83–88% of cold-topped clouds were liquid at the base, while small-particle (low-radar-reflectivity) precipitation was mostly liquid below-cloud, contrasting with large-particle precipitation that was predominantly mixed or ice-phase. This insight is crucial for understanding the radiative properties and climate impacts of Southern Ocean low clouds.

Tansey, E., Marchand, R., Alexander, S. P., Klekociuk, A. R., & Protat, A. (2023). Southern Ocean Low Cloud and Precipitation Phase Observed During the Macquarie Island Cloud and Radiation Experiment (MICRE). Journal of Geophysical Research: Atmospheres, 128(17). Portico. https://doi.org/10.1029/2023jd039205