ARB Research Seminar

This page updated June 19, 2013

Nitrogen Oxide Emissions and Chemistry : Implications for Air Quality Control Strategies in a Warmer Climate

Ronald C. Cohen, Ph.D., Department of Chemistry, University of California, Berkeley

May 30, 2008
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA



Progress in understanding the links between temperature, biogenic, volatile organic compounds (VOC), nitrogen oxides (NOₓ), ozone and nitrate aerosol will be discussed. In particular we use observations and model analyses from California experiments to highlight 1) the growing consensus that daytime free radical chemistry is faster than current models predict in the presence of biogenic VOC (as first suggested by Thornton et al. 2002), 2) observations of day-of-week variations in NOₓ from the surface and space based instruments and their links to emission inventories and to day-of-week variations in hydroxyl radical (OH) and thus to day-of-week variations in isoprene and aerosol, and 3) the role of nitrate (NO₃) radical chemistry in production of wintertime NO₃ aerosol. Taken together, these results imply NOₓ controls will be more effective than current models predict, both now and in a future warmer climate.

Speaker Biography

Ronald C. Cohen, Ph.D., is a professor in both the Chemistry and Earth & Planetary Science Departments at the University of California, Berkeley, and Director of the Berkeley Atmospheric Science Center. Dr. Cohen is also, a faculty scientist in the Energy and Environment Technologies Division at the Lawrence Berkeley National Laboratory. In 2006-2007 he was a visiting Professor in the Biogeochemistry Division of the Max Planck Institute for Chemistry, Mainz.

Dr. Cohen's research focuses on the chemistry and atmosphere-biosphere exchange of atmospheric nitrogen oxides and water as these processes relate to atmospheric oxidation rates, tropospheric ozone, aerosol properties and climate. Dr. Cohen is well known for his observations demonstrating the widespread role of alkyl and multifunctional nitrates in ambient air chemistry and for his development of new technologies for specific measurement of the NO₂ and NO₃ radicals. Recent nitrogen oxide work has emphasized the role of lightning and convection (Bertram et al., Science January 2007), observing agricultural NOₓ emissions from space (Bertram et al. GRL 2005) and using in situ observations to evaluate the accuracy of space-based NO₂ measurements (Martin, et al. JGR 206, Buscela, et al. JGR 2008), using weekday/weekend variations in NOₓ emissions to study the chemistry of urban plumes (Murphy et al. ACP 2007) and measuring eddy-covariance fluxes over a Ponderosa Pine Forest (Farmer et al. ACP 2006). Cohen has also recently focused on aerosol and cloud properties through experiments measuring rates of evaporation (Cappa et al. 2005 and 2007, Smith et al. 2006, Drisdell et al. 2008).

Dr. Cohen is co-author of over 100 peer reviewed papers. He has mentored eleven students who have completed their Ph.D. and eleven graduate students and two postdoctoral fellows are currently working in his research group. Dr. is a member of the American Association of the Advancement of Science, the American Geophysical Union, the European Geophysical Union, and the American Chemical Society. Cohen's research has been recognized with the Regents Junior Faculty Fellowship (1998), a Hellman Faculty Fellowship (1999) and NASA group achievement awards (1998, 2005).

Dr. Cohen received his B.A. Wesleyan University, (1985), Ph.D. in Chemistry, UC Berkeley (1991), was a postdoctoral fellow and research associate at Harvard University 1991-1996. Dr. Cohen joined the UC Berkeley faculty in 1995.

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