Classification of the Below-Cloud Mixing State Over the Southern Ocean Using In-Situ and Remotely-Sensed Measurements

• DOI: 10.1002/essoar.10502904.2
• Publication Date: 2021-03-19T19:32:28Z
• Authors: Sean Hartery; Peter Kuma; Mike J Harvey; Adrian J. McDonald
• Keywords: Ceilometer; Mixed layer; Cirrus; Cloud height; Cloud fraction

We demonstrate that the relationship between abundance of particulate surface area observed at sea-level and measurements backscattered light by a ceilometer can be used to classify mixing state atmospheric layer beneath lowest cloud, where is defined Spearman Rank correlation. The accuracy this correlation-based method was compared two methods detecting boundary decoupling based on radiosonde measurements. An optimized version new methodology correctly determined below-cloud for 76 ± 4% radiosondes available comparison. Further, it more accurate than an alternative ground-based metric determine state. For majority time series in which correlation analysis could applied, well-mixed (54%), or else fog present (27%), indicated aerosol particles often have direct pathway into low-cloud (81%). In remaining period, near-surface stable near ocean decoupled from overlying cloud (19%). Forecasts Antarctic Mesoscale Prediction System also support our findings, showing conditions mix occur 84% over open Southern Ocean. As result, measured are tightly coupled formation Ocean, highlighting utility shipborne observations region.