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Paul B. Shepson
Professor—Analytical and Atmospheric Chemistry
Email: pshepson@purdue.edu
Phone: 765-494-7441
Office: BRWN 5171C
For Professor Shepson's individual Home Page click here.
The Shepson group is involved in fundamental studies of the chemistry of the Earth’s atmosphere, and specifically, photochemistry that occurs in the lowest 10-15 km, i.e. the troposphere. Most of our research questions ultimately relate to understanding factors that influence tropospheric ozone, a toxic but also essential component of the lower atmosphere. Research activities involve a wide and interconnected array of laboratory experiments, analytical methods development, field measurement campaigns, and supporting computer modeling activities. We currently are pursuing problems in three broad areas:
Studies of the impact of forest-derived natural hydrocarbons
This work focuses improving our understanding of the role of natural hydrocarbons, such as isoprene, in controlling the production of O3, and the removal of NOx (as shown in the Figure 1), and how atmospheric compositional change can influence forest biochemistry. (see Starn et al., 1998).
Studies of the role of snow phase photochemistry in the Arctic
For the past decade, we have been studying a remarkable phenomenon characterized by complete destruction of all the O3 in the lower atmosphere just above the ocean surface at sunrise (March/April) in the Arctic. 
Much of our work has been conducted at or near a laboratory at the Canadian Forces Station at Alert, N.W.T. (82.5oN; see photo of lab in Figure 2), where we recently discovered that this process is initiated by photochemistry that occurs in the snowpack. (see Sumner and Shepson, 1999).
Analytical methods development for rapid and trace level atmospheric measurements
We are actively pursuing development of new analytical methods, e.g. involving use of ion trap mass spectrometry, that enable quantitative atmospheric measurements at trace levels. (see Colorado et al., 1998).
Education
B.S., 1978, SUNY College at Cortland; Ph.D., 1982, Pennsylvania State University.Recognitions
- Assistant and Associate Professor, York University, 1987-1994
- Research Chemist, U.S. EPA, 1983-1987
Selected Publications
- Cavender A. E.;Biesenthal, T. A.;Bottenheim, J. W.;Shepson, P. B., Volatile organic compound ratios as probes of halogen atom chemistry in the Arctic . Atmospheric Chemistry and Physics 2008 , 8 , 1737-1750.
- Garman K. E.;Wyss, P.;Carlsen, M.;Zimmerman, J. R.;Stirm, B. H.;Carney, T. Q.;Santini, R.;Shepson, P. B., The contribution of variability of lift-induced upwash to the uncertainty in vertical winds determined from an aircraft platform . Boundary-Layer Meteorology 2008 , 126 , 461-476.
- Lockwood A. L.;Filley, T. R.;Rhodes, D.;Shepson, P. B., Foliar uptake of atmospheric organic nitrates . Geophysical Research Letters 2008 , 35 , -.
- Carignano M. A.;Shepson, P. B.;Szleifer, I., Ions at the ice/vapor interface . Chemical Physics Letters 2007 , 436 , 99-103.