An Integrated View on Coupled Aerosol-Cloud Interactions

ended

Despite their abundance in the Earth’s atmosphere, cloud formation and evolution are still poorly understood. This is particularly true for the interactions clouds have with atmospheric aerosol particles and their precursor vapors, which hampers our knowledge on the role that clouds and precipitation play in the climate system and in governing air quality. I argue that a major fraction of these uncertainties stem from inconsistencies and discontinuities in treating 1) the molecular phase transitions driving the dynamic cloud formation processes; 2) the interplay between atmospheric chemical composition and atmospheric dynamics; 3) the complex role that clouds play as both sources and sinks of particulate matter, but also as subjects to changes driven by aerosol particles. INTEGRATE will address these inconsistencies, and acquire a comprehensive picture of the phase transitions leading to cloud formation over the relevant scales. INTEGRATE will fill the key knowledge gaps through work in 1) the process scale, developing, applying and evaluating descriptions of molecular phase transitions within clouds; 2) the cloud scale, integrating the relevant chemical, microphysical and dynamic phenomena in a 3-dimensional cloud simulation framework; 3) the regional and global scales, studying interactions between aerosol loadings and clouds in past, present and future climates using chemical transport and earth system modeling. Systematic approaches for bridging the gap between the various time and spatial scales will also be developed within INTEGRATE. If successful, INTEGRATE will open new avenues for 1) fundamental understanding of the physics and chemistry of atmospheric phase transitions; 2) improved climate projections and ultimately better policies for reaching the targets of the Paris agreement; 3) better predictions of factors controlling air quality, hence facilitating the design of better policies to improve the quality of the air we breathe.