Characterizing the Shape of Cloud Particle Size Distributions in High-Latitude Marine Cold-Air Outbreaks

Abstract

Marine cold-air outbreaks (MCAOs) drive significant evolutions in marine boundary layer clouds and play a crucial role in high-latitude climate systems. This study examines the variability of cloud particle size distributions (PSDs) in high-latitude MCAOs and how well their spectral shapes are represented by the gamma shape parameter μ used in model bulk microphysics parameterizations. Aircraft in situ measurements from 20 flights in stratocumulus and cumulus cloud regimes within MCAO conditions were collected during two recent field campaigns: Arctic cold-air outbreak conducted over the Arctic-Nordic seas in March 2022 and the M-phase conducted over the sub-Arctic Labrador Sea in October–No..