Overview of NASA’s Aerosol Cloud Meteorology Interactions over the Western Atlantic Experiment (ACTIVATE) (Invited)

The NASA Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) conducted 179 flights with two aircraft over the western North Atlantic Ocean to study aerosol-cloud-meteorology interactions. The combination of a higher-flying King Air and lower-flying HU-25 Falcon, coupling in situ and remote sensing instruments, characterized trace gases, aerosol particles, clouds, and meteorological variables with data collected nearly simultaneously below, within, and above marine boundary layer (MBL) clouds. Flights spanning warm and cold seasons across three years (2020-2022) provide nearly 1200 combined hours of measurements from coordinated flights of two aircraft across a noteworthy range of values associated with aerosol particles, cloud properties (including particle size and phase), trace gases, and meteorology. This allows for robust calculations of aerosol-cloud interactions and assessing how well models simulate a range of MBL clouds from stratiform to cumulus. Results point to the importance of conducting such campaigns across different seasons as drivers of cloud droplet number concentration, including aerosol particles and MBL dynamics, vary between winter and summer months with a stronger potential to convert particles into cloud droplets in the winter. Models of varying complexity highlight some skill in simulating winter and summer cloud types, but also identify challenges that still need to be addressed such as treatment of turbulence, wet scavenging, mesoscale organization, and aerosol-cloud-meteorology interactions. Remote sensing advances range from new retrieval methods for ocean surface wind speeds, vertically-resolved aerosol number and cloud condensation nuclei concentrations, cloud drop number concentrations, and cloud phase classification. This presentation will highlight scientific and technological advances from the ACTIVATE project.