Assistant Professor of Chemistry & Mechanical Engineering
Atmospheric chemistry, aerosol instrumentation, single-particle analysis, mass spectrometry, laser spectroscopy, heterogeneous chemistry, combustion, particle hygroscopicity, cloud nucleation, aerosol-cloud-climate interactions
Dr. Ryan Sullivan is an Assistant Professor of Chemistry and Mechanical Engineering at Carnegie Mellon University, beginning in January 2012. He is also a faculty member in the Centre for Atmospheric Particle Studies.
Ryan Sullivan has a background in atmospheric and analytical chemistry, single-particle analysis, heterogeneous kinetics, and cloud nucleation research. His research interests include the development of improved aircraft-deployable analytical instrumentation to characterize individual particles in the atmosphere in real-time. These instruments are used to investigate the physicochemical properties of atmospheric particles emitted and produced from a variety of sources, the chemical processes they experience during atmospheric transport, and how these processes modify the ability of particles to nucleation both warm cloud droplets and ice crystals, thus altering cloud properties and the Earth's climate. These research endeavours involve equal parts instrument development, laboratory experiments, and field measurements.
Particles in the atmosphere exist in a wide variety of shapes, sizes, and chemical compositions. These properties are highly dynamic, constantly evolving as the particles respond to changes in their gas-phase environment. This makes the study of atmospheric aerosol particles both challenging and fascinating. The important but still poorly understood roles that particles play in influencing air quality, the atmosphere's chemical balance, energy balance, cloud nucleation, biogeochemical cycles, and other important climate feedbacks motivate our interest in increasing our understanding of the chemical behaviour of particles in our atmosphere. Our comprehension of these processes is currently limited by the instrumentation available to measure key properties of individual atmospheric particles.
We investigate these important physicochemical particle properties using custom single-particle instruments that allow us to rapidly characterize atmospheric aerosols in real-time, one particle after another. We are developing improved analytical methods to measure individual particles using laser ablation mass spectrometry, and laser spectroscopy. These new instruments are utilized in both laboratory studies and field experiments (from ground, ship, and aircraft sampling platforms) to determine the kinetics and products of a variety of atmospheric chemical aging processes (e.g. heterogeneous reaction, aqueous-phase chemistry, gas-to-particle conversion, photochemistry, new particle formation). Small cloud simulation chambers are also used to determine the ability of the chemically processed particles to nucleate both warm cloud droplets, and ice crystals via heterogeneous ice nucleation.
Single-particle analysis is an important analytical tool that allows us to determine how the myriad chemical constituents are distributed between individual particles (mixing state). As all particle properties (interaction with radiation, heterogeneous kinetics, hygroscopicity, heterogeneous ice nucleation, toxicity, etc.) are dictated by each particle's unique size and chemical composition, single-particle analysis is required to determine the exact relationships between the sources of atmospheric particles, their size and chemical composition, how they behave chemically in the atmosphere, and what their resulting important environmental effects are.
|2012||Assistant Professor of Chemistry & Mechanical Engineering, Carnegie Mellon University|
|2009–2011||Post-Doctoral Fellow and Research Scientist, Colorado State University|
|2008||Ph.D., Chemistry, University of California, San Diego|
|2006||M.Sc., Chemistry, University of California, San Diego|
|2002||Hon. B.Sc., Chemistry, University of Toronto|
Creamean, J. M., Suski, K. J., Rosenfeld, D., Cazorla, A., DeMott, P. J., Sullivan, R. C., White, A. B., Ralph, M. F., Minnis, P., Comstock, J. M., Tomlinson, J. M., & Prather, K. A. (2013). Dust and Biological Aerosols from the Sahara and Asia Influence Precipitation in the Western US. Science, In press.
Prenni, A. J., Sullivan, A. P., Sullivan, R. C., Kreidenweis, S. M., & Rogers, D. G. (2012). Biomass burning as a potential source for atmospheric ice nuclei: Western wildfires and prescribed burns. Geophysical Research Letters, 39(11), L11805.
Levin, E. J., Prenni, A. J., Petters, M. D., Kreidenweis, S. M., Sullivan, R. C., Atwood, S. A., Ortega, j., DeMott, P. J., & Smith, J. N. (2012). An annual cycle of size-resolved aerosol hygroscopicity at a forested site in Colorado. Journal of Geophysical Research, 117, D06201.
Suda, S. R., Petters, M. D., Matsunaga, A., Sullivan, R. C., Ziemann, P. J., & Kreidenweis, S. M. (2012). Hygroscopicity frequency distributions of secondary organic aerosols. Journal of Geophysical Research, 117(D4), D04207.
Sullivan, R.C., Miñambres, L., DeMott, P.J., Prenni, A.J., Carrico, C.M., Levin, E., Kreidenweis, S.M., Chemical processing does not always impair heterogeneous ice nucleation properties of mineral dust particles, Geophysical Research Letters, 37, L24805, doi:10.1029/2010GL045540, 2010.
Petters, M.D., Kreidenweis, S.M., Prenni, A.J., Sullivan, R.C., Carrico, C.M., Koehler, K.A., Ziemann, P.J. The role of molecular size in cloud droplet activation, Geophysical Research Letters, 36, L22801, doi:10.1029/2009GL040131, 2009.
Sullivan, R.C., Moore, M.J.K., Petters, M.D., Kreidenweis, S.M., Roberts, G.C., Prather, K.A. Timescale for hygroscopic conversion of calcite mineral particles through heterogeneous reaction with nitric acid, Physical Chemistry Chemical Physics, 11, 7826-7837, 2009.
Sullivan, R.C., Moore, M.J.K., Petters, M.D., Kreidenweis, S.M., Roberts, G.C., Prather, K.A. Effect of chemical mixing state on the hygroscopicity and cloud nucleation properties of calcium mineral dust particles, Atmospheric Chemistry and Physics, 9, 3303-3316, 2009.
Sullivan, R.C., Prather, K.A. Investigations of the diurnal cycle and mixing state of oxalic acid in individual particles in Asian aerosol outflow. Environmental Science & Technology, 41 (23), 8062–8069, 2007.
Sullivan, R.C., Guazzotti, S.A., Sodeman, D.A., Prather, K.A. Direct observations of the atmospheric processing of Asian mineral dust. Atmospheric Chemistry and Physics, 7, 1213-1226, 2007.
Sullivan, R.C., Thornberry, T., and Abbatt, J.P.D. Ozone decomposition kinetics on alumina: effects of ozone partial pressure, relative humidity and repeated oxidation cycles, Atmospheric Chemistry and Physics, 4, 1301-1310, 2004.