Research summary
Contributions concern instrumentation and field characterization of submicron atmospheric aerosols. The Aerodyne aerosol mass spectrometer (AMS) was developed to provide real-time, size-resolved chemical composition of non-refractory submicron particles (~50-1,000 nm) by combining an aerodynamic lens inlet with thermal vaporization and electron-impact mass spectrometry, with quantitative response demonstrated initially on NH4NO3 aerosol [4] and reviewed comprehensively in Mass Spectrometry Reviews [3]. High-resolution time-of-flight AMS data were used to derive elemental O/C, OM/OC, H/C, and N/C ratios for primary, secondary, and ambient organic aerosol in urban environments, with O/C ranging from 0.2 to 0.8 and exhibiting a diurnal cycle driven by primary emissions and photochemical SOA production [5]. Positive matrix factorization applied to AMS organic-aerosol spectra from the Pittsburgh Air Quality Study resolved hydrocarbon-like OA (HOA, primary combustion) and two oxygenated components (highly oxygenated OOA-1 correlated with sulfate; semi-volatile OOA-2 correlated with nitrate and chloride), framing a now-standard interpretive scheme for unit-mass-resolution data [6]. A 37-campaign synthesis demonstrated that oxygenated organic aerosol dominates total OA across the Northern Hemisphere midlatitudes (64%, 83%, and 95% in urban, urban downwind, and rural/remote sites) and is not primarily derived from HOA oxidation [2]. A unifying framework in Science described OA atmospheric evolution as a continuous trajectory toward higher oxidation, lower volatility, and greater hygroscopicity, reconciling lab and field observations [1]. Companion work showed rapid anthropogenic SOA formation exceeding state-of-the-art chamber-based model predictions [7] and provided direct observations of atmospheric nucleation in the sub-2 nm size range, defining three distinct regimes for neutral-pathway aerosol formation [8]. Methodologically the work pairs custom mass-spectrometric instrumentation with statistical decomposition (PMF) and integrated framework-building from multi-campaign datasets.
Recent publications
- Evolution of Organic Aerosols in the AtmosphereDOI
- Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically鈥恑nfluenced Northern Hemisphere midlatitudesDOI
- Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometerDOI
- A large source of low-volatility secondary organic aerosolDOI
- Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Submicron ParticlesDOI
- O/C and OM/OC Ratios of Primary, Secondary, and Ambient Organic Aerosols with High-Resolution Time-of-Flight Aerosol Mass SpectrometryDOI
- Interpretation of organic components from Positive Matrix Factorization of aerosol mass spectrometric dataDOI
- Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleationDOI
- Secondary organic aerosol formation from anthropogenic air pollution: Rapid and higher than expectedDOI
- Direct Observations of Atmospheric Aerosol NucleationDOI
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Email Douglas R. Worsnop 6-12 months before your application deadline. Read several recent papers and reference specific work in your message. Use our how to email a Japanese professor guide for the proven email structure.
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External profiles
- ORCID: https://orcid.org/0000-0002-8928-8017
- OpenAlex: openalex.org
Profile compiled from public sources (Researchmap, OpenAlex, Hokkaido University faculty directory). Last refreshed 2026-05. Report incorrect information.