Project Grant 2246488

COLLABORATIVE RESEARCH: ELUCIDATING THE ROLE OF NATURAL AEROSOLS IN MODULATING BOUNDARY LAYER CLOUDS AND PRECIPITATION IN THE SOUTHERN OCEAN -THE SOUTHERN OCEAN IS AN IMPORTANT REGION FOR UNDERSTANDING CURRENT AND FUTURE CLIMATE DUE TO A PERSISTENT MIX OF CLOUD TYPES THAT AFFECT THE EARTH?S ENERGY BALANCE. AN IMPROVED UNDERSTANDING OF SOUTHERN OCEAN CLOUDS RELIES ON BETTER MEASUREMENTS OF AEROSOLS, WHICH ARE SMALL PARTICLES THAT CLOUD DROPLETS AND ICE CRYSTALS FORM ON. THIS PROJECT WILL DEPLOY A SUITE OF INSTRUMENTATION ON A SERIES OF RESEARCH VESSEL CRUISES CONDUCTED BY AUSTRALIAN COLLABORATORS, AND AT A LOCATION IN ANTARCTICA, TO MEASURE THESE AEROSOLS. THE IMPACT OF THE PROJECT WILL BE TO IMPROVE REPRESENTATION OF AEROSOL-CLOUD INTERACTIONS AND CLOUD-CLIMATE FEEDBACKS OVER THE SOUTHERN OCEAN, WITH A VIEW TOWARDS IMPROVED CLIMATE PROJECTIONS. THERE IS A SIGNIFICANT OUTREACH COMPONENT TO THE WORK, WHERE THE RESEARCHERS WILL INTERACT WITH K-12 CLASSROOMS GLOBALLY THROUGH ON-LINE AND IN PERSON ACTIVITIES. THE PROJECT ALSO REPRESENTS STRONG INTERNATIONAL COLLABORATION. THE RESEARCH TEAM WILL CONDUCT AN OBSERVATIONAL AND MODELING STUDY OF THE ROLE OF NATURAL AEROSOLS IN MODULATING THE PROPERTIES OF CLOUDS AND PRECIPITATION IN THE SOUTHERN OCEAN REGION. THE SOUTHERN OCEAN IS ONE OF THE LEAST POLLUTED PLACES ON EARTH AND THE DISTANCE FROM DUST SOURCES MEANS THAT AEROSOLS ARE DOMINATED BY BIOGENICALLY DERIVED SULFATES, INCLUDING IMPACTS FROM MARINE PRIMARY PRODUCTIVITY. THE SOURCES AND ABUNDANCES OF ICE-NUCLEATING PARTICLES (INPS) REMAIN POORLY QUANTIFIED OVER THE SOUTHERN OCEAN AND ANTARCTICA. THIS PROJECT WILL TAKE ADVANTAGE OF FOUR UPCOMING VOYAGES ON AUSTRALIAN RESEARCH VESSELS, AND A DEPLOYMENT AT DAVIS STATION, ANTARCTICA, TO DOUBLE THE VOLUME OF EXISTING SURFACE-BASED MEASUREMENTS TO CONSTRAIN SOUTHERN OCEAN AEROSOL AND CLOUD PROPERTIES. THE RESEARCH TEAM WILL CONTRIBUTE TO THE PRE-EXISTING OBSERVATIONAL CAMPAIGNS BY PROVIDING ADDITIONAL RADIOSONDE MEASUREMENTS AND COLLECTING AEROSOL, SEAWATER, SEA ICE, SNOW, AND SOIL FOR OFFLINE INP AND DNA ANALYSES. THE RESEARCHERS WILL THEN CO-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 CONDENSATION NUCLEI (CCN) AND CLOUD DROPLET NUMBER CONCENTRATION (ND) OVER THE PRISTINE OCEANS DURING THREE SEASONS DERIVED FROM SHIP-BASED SOURCES, 2) QUANTIFICATION OF THE SUSCEPTIBILITY OF ND TO SOURCES OF AEROSOL TYPES AND PROCESSES TO PROVIDE IMPORTANT CONSTRAINTS ON THE OBSERVED ND, AND 3) DOCUMENTATION OF LATITUDINAL AND SEASON VARIABILITY IN INPS AND PRECIPITATION OCCURRENCE AND PHASE. THIS AWARD REFLECTS NSF'S STATUTORY MISSION AND HAS BEEN DEEMED WORTHY OF SUPPORT THROUGH EVALUATION USING THE FOUNDATION'S INTELLECTUAL MERIT AND BROADER IMPACTS REVIEW CRITERIA.