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Paul B. Shepson

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).


  • Ph.D., 1982, Pennsylvania State University
  • B.S., 1978, SUNY College at Cortland


  • American Chemical Society Award for Creative Advances in Environmental Science & Technology , 2015
  • Assistant and Associate Professor, York University, 1987 - 1994
  • Research Chemist, U.S. EPA, 1983 - 1987


Purdue University, West Lafayette, IN 47907 (765) 494-4600

Department of Chemistry, 560 Oval Drive, West Lafayette, Indiana 47907-2084 | Telephone: (765) 494-5200 | Fax: (765) 494-0239

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