Influence of Multiphase Chemistry on Oxygenated Organic Aerosol Formation in the New York City Region
MITCHELL ROGERS, Taekyu Joo, Tori Hass-Mitchell, Benjamin A. Nault, Mia Tran, Manjula Canagaratna, Joseph Roscioli, Jordan Krechmer, Andrew Lambe, Drew Gentner,
Yale University Abstract Number: 434
Working Group: Urban Aerosols
AbstractAqueous-phase uptake and processing of water-soluble organic compounds contributes significantly to atmospheric secondary organic aerosol (SOA) with variations between regions. Current models predict that changes in climate and emissions will lead to increases in hygroscopic inorganic aerosol components and aerosol liquid water content that may further promote the relative importance of aqueous processing pathways. Using summer 2022 observations in New York City from the NYC-METS (New York City metropolitan Measurements of Emissions and TransformationS) campaign and ASCENT (Atmospheric Science and Chemistry mEasurement NeTwork), we evaluate the influence of aqueous-phase aerosol processing on ambient SOA across two different field sites in New York City. Two Aerodyne aerosol chemical speciation monitors (ACSM) were deployed with supporting measurements of black and brown carbon and reactive gases (e.g., NO
x, O
3, SO
2) at an elevated rooftop site in densely populated Manhattan, NY and a long-term monitoring site in Queens, NY. Using these measurements, we evaluate changes in aerosol production and composition as a function of changes in relative humidity and aerosol liquid water content. Variations in sulfate and other environmental factors at the two sites are examined for their influence on oxygenated organic aerosol (OOA), which is separated into less and more oxidized aerosols using source apportionment of ACSM measurements. The relative role of aqueous-phase processing varied with meteorological conditions, with clear OOA enhancements (e.g., 1+ µg/m
3) during several hot and humid periods highlighting the important, yet variable, role of aqueous-phase SOA production. The less oxidized OOA identified in the less densely populated Queens, NY site showed the strongest sensitivity to temperature, humidity, and sulfate. These results and the sensitivity to climate are interpreted within the context of our current understanding of summertime aerosol abundances and dynamics and their role in New York City and downwind air quality.