Cloud and Aerosol Interactions over the Southern Ocean

CAISO is a project that  involves deployment of aerosol and cloud instruments on a series of research vessel cruises and in Antarctica from 2023 and possibly into 2027. Specifically, additional radiosondes and collections of aerosol and seawater samples for offline ice nucleating particle (INP) and bioaerosol measurements have been conducted on voyages including the May 2023 SOTS (Southern Ocean Time Series), Nov-Dec 2023 SWOT (Smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania), and Jan-Mar 2024 MISO (Multidisciplinary Investigations of the Southern Ocean: Linking physics, biogeochemistry, plankton, aerosols, clouds, and climate) voyages. Future voyages will include the Mar-May 2025 Denman, Mar-Apr 2025 SOTS, May 2025 COAST-K (Clean Ocean AIr Sampling upwind of Tasmania – Kennaook), and two possible voyages in 2026 and 2027. Land-based measurements of aerosol size distributions and filter collections for INPs and bioaerosols have been ongoing at Davis Station, Antarctica since Dec 2023. These additional measurements will double the volume of existing surface-based measurements to constrain Southern Ocean aerosol and cloud properties. The data will be used to develop process-oriented aerosol and cloud model diagnostics for parameterization testing and development in the Community Earth System Model (CESM). The project will result in the following deliverables: 1) Documentation of the latitudinal gradients in cloud-active aerosols and cloud droplet number concentration, 2) Quantification of the susceptibility of cloud droplet numbers to sources of aerosol types, and 3) Documentation of latitudinal and seasonal variability in INPs and precipitation occurrence and phase.

Platform: Land-based, Investigator, and Nuyina 

Location: Davis Station and several SO cruises

Timing:  May 2023 – May 2025 (possible extension to March 2027)

Jay Mace (
Jessie Creamean (
Christina McCluskey (
Gannet Hallar (