Dynamical Drivers of Aerosol-Cloud-Radiation Interactions over the North Atlantic Ocean

The occurrence of extra-tropical boundary layer clouds over the North Atlantic ocean is closely linked to the evolution of midlatitude weather disturbances. The synoptic conditions that give rise to the formation of low clouds are also responsible for the transport of continental aerosols over the adjacent ocean, where aerosol-cloud interactions are likely to occur. Interestingly, the dynamical drivers of low clouds over the North Atlantic ocean depart from those observed in classical stratocumulus regimes in the subtropics. Dramatic changes in advection, subsidence, and surface heat fluxes, induce rapid boundary layer transitions, stronger updraft speed, and, consequently, stronger cloud condensation nuclei activation than those observed in the subtropics. We combine in-situ, airborne/satellite remote sensing observations, and reanalysis data to analyze variability in cloud microphysics, aerosol-cloud interactions, and the role of dynamical drivers in the evolution of North Atlantic low clouds, with a focus on the oceanic region adjacent to continental U.S. Furthermore, we describe how different modes of synoptic variability can impact cloud formation, aerosol activation and free-tropospheric entrainment.