First-Light Observations from EarthCARE’s Cloud Profiling Radar Reveal Insights intoMicrophysics-Dynamics Coupling of Marine Cold-Air Outbreaks Clouds

Marine cold-air outbreaks (MCAO) strongly impact the radiative effects of clouds, playing a crucial role in the high-latitude climate system.  MCAO clouds initially begin as shallow stratiform cloud streets near the ice edge and evolve into broken cellular convection farther downstream. Although these clouds undergo substantial changes in both macro- and microphysical properties during their evolution, a comprehensive understanding of their relationship with cloud dynamics has been limited by observational constraints. The recent launch of the EarthCARE satellite on May 28, 2024, carrying the first-ever spaceborne Doppler radar (Cloud Profiling Radar, CPR), provides unprecedented opportunities to investigate vertical motion within clouds from
space. Here, we analyze the Lagrangian trajectories of cold air outbreaks since the time they leave the Arctic sea ice edge and observe MCAO clouds with the EarthCARE CPR as they form over the Norwegian and Barents Seas from December 2024 to May 2025 at 0.25 by 0.25 resolution.  We show that the CPR observations successfully capture the distinct developmental stages of MCAO clouds.  Notably, despite the inherent observational challenges from satellite platforms, we identify enhanced riming signatures associated with strong updrafts and abundant supercooled liquid water, which increases ice particle sedimentation velocities. Our results provide the first comprehensive view of the evolution of cloud structure, microphysical processes, and dynamic features in MCAO clouds over extended spatial and temporal scales. These insights advance our understanding of MCAO cloud processes and can inform future improvements in numerical climate models.