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Paul Shepson


Distinguished Professor



- Pennsylvania State University

Research Topics:

Atmospheric Chemistry and climate change, Aviation, Arctic and coastal halogen chemistry, greenhouse gas source and sink measurements, atmospheric aerosols, climate change communications


  • Bio/Research


    Atmospheric Chemistry and Climate Change Research in the Shepson Group

    The Shepson Group in the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University conducts research on atmospheric chemistry and composition, interactions between the atmosphere and the surface, and how climate change is impacting the physics, biology, and chemistry at the surface and in the atmosphere. We are currently looking for graduate students and postdocs who might be interested in working on one of these projects:

    1. Development of methods for the quantitative determination of greenhouse gas (focusing on CO 2 and CH 4 ) emission rates from urban environments.

    We are using a combination of aircraft-based measurements, using the Airborne Laboratory for Atmospheric Research (ALAR; see photo at right), along with tower-based observations, emissions models, chemical transport models, and inverse modeling, to enable development of highly accurate and precise methods for quantifying greenhouse gas (GHG) emission rates. This work connects to New York City, State, national, and international efforts to mitigate climate change. We conduct this research in collaboration with other groups nationally, and with colleagues at the National Institute for Standards and Technology (NIST). We have projects for aviation-based observations, and atmospheric model development for GHG emission rate estimates, for the U.S. northeast corridor.

    2.   Studies of halogen chemistry in a changing Arctic Ocean environment.

    We have been working for several decades on studies of halogen chemistry in the Arctic, that occurs as a result of ocean-sea ice-snowpack-aerosol interactions. These are highly complex, and changing due to climate change, as shown in the Figure at right, from Thomas et al., Elementa, 2019. We are looking for students or postdocs interested in working on an upcoming aircraft-based field project in the Alaska North Slope region.


    Turnbull, J., et al., Environ. Sci. Technol., DOI: 10.1021/acs.est.8b05552, 2018.

    Wang, S., et al., Proc. Nat. Acad. Sci., 116, 14479-14484, 2019.

    Green River Films created the film “ Young Ice” with our research group during the BROMEX campaign in 2012 along the north coast of Alaska.  The film captures how our team operates the Airborne Laboratory for Atmospheric Research (ALAR), an instrumented Beechcraft BE76 Duchess aircraft and take samples around the sea ice and over North America’s largest oil drilling operation in Prudhoe Bay.

    Our research group will return to the region in 2022 for the NSF project “ Collaborative Research: Chemistry in the Arctic-Clouds, Halogens, and Aerosols,” or CHACHA. The goal of the project aims to improve the understanding of atmospheric chemistry in the Arctic that impacts ozone, particulate matter and cloud chemical composition in the context of the rapidly changing Arctic atmosphere. The CHACHA team will conduct airborne measurements from February 2022 to April 2022 of halogens (derived from sea salt on the frozen ocean surface) and other relevant chemicals as they exist within the gas phase, within suspected particles, and cloud droplets around the Chukchi and Beaufort Seas and the Alaska North Slope regions.

    For CHACHA, we will use two instrumented aircrafts — the University of Wyoming King Air and the Purdue University Airborne Laboratory for Atmospheric Research (ALAR).

  • Publications


    Recent Publications


    Salmon, O. E.G P. B. Shepson, X. Ren, R. R. Dickerson, B. H. Stirm, S. S. Brown, D. L. Fibiger, E. E. McDuffie, K. R. Gurney, J. A. Thornton, Top-down Estimates of NOx and CO Emissions from Washington, D.C.-Baltimore During WINTER, J. Geophys. Res.,

    in preparation for submission, 2017.

    Slade, J. H, C. de Perre, L. Lee, and P. B. Shepson, Nitrate radical oxidation of g-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields, Atmos. Chem. Phys., 17, 8635–8650, 2017.

    Custard, K. D.G, A. R. W. RasoG, P. B. Shepson, R. M. Staebler, and K. A. Pratt, Production and Release of Molecular Bromine and Chlorine from the Arctic Coastal Snowpack, Earth and Space Chemistry, DOI: 10.1021/acsearthspacechem.7b00014,


    Raso, A. R.G W., K. D. Custard, N. W. May, D. J. Tanner, M. K. Newburn, L. Walker, R. Moore, L. G. Huey, M. L. Alexander, P. B. Shepson, and K. A. OPratt, Active Molecular Iodine Snowpack Photochemistry in the Arctic, Proc. Nat. Acad. Sci., doi:10.1073/pnas.1702803114, 2017.

    Artiglia, L., J. Edebeli, F. Orlando, S. Chen, P. C. Arroyo, A. Gilgen, T. Bartels-Rausch, A. Kleibert, M. Vazdar, M. A. Carignano, J. S. Francisco, P. B. Shepson, I. Gladich and M. Ammann, A surface-stabilized ozonide triggers bromide oxidation at the aqueous

    solution – vapor interface, Nature Comms., DOI: 10.1038/s41467-017-00823, 2017.

    Bondy, A. L. B. Wang, A. Laskin, R. L. Craig, V. M. NhliziyoU, S. B. Bertman, K. A. Pratt, P. B. Shepson, and A. P. Ault, Inland Sea Spray Aerosol Transport and Incomplete Chloride Displacement: Varying Heterogeneous Reactivity Observed during SOAS, Environ. Sci. Technol., 10.1021/acs.est.7b02085, 2017.

    Gurney, K.R., J. Liang, R. Patarasuk, D. O’Keeffe, J. Huang, M. Hutchins, T. Lauvaux, J. C. Turnbull, and P. B. Shepson, 2017, Reconciling the differences between a bottom-up and inverse-estimated FFCO2 emissions estimate in a large US urban area, Elem. Sci. Anth., 5: 44, DOI:

    N. L. Miles, S. J. Richardson, T. Lauvaux, K. J. Davis, N. V. Balashov, A. Deng, J. C. Turnbull, C. Sweeney, K. R. Gurney, R. Patarasuk, I. Razlivanov, M. O. L. CambalizaP and P. B. Shepson, Quantification of urban atmospheric boundary layer greenhouse gas

    dry mole fraction enhancements in the dormant season: Results from the Indianapolis Flux Experiment (INFLUX), Elem Sci Anth, 5: 27, DOI:

    Davis, K. J., A. Deng, T. Lauvaux, N. L. Miles, S. J. Richardson, D. Sarmiento, K. R. Gurney, R. M. Hardesty, A. Brewer, P. B. Shepson, R. M. Harvey, M. O. CambalizaP, C. Sweeney, J. Turnbull, J. Whetstone, and A. Karion, The Indianapolis Flux Experiment (INFLUX): A test-bed for developing anthropogenic greenhouse gas emission measurements, Elem. Sci. Anth., 5: 21, DOI:, 2017.

    Shou, Y.-X., Zhang, D.-L., Ide, K., Dickerson, R. R., Ren, X., Heimburger, A.P, and Shepson, P. B., Ensemble Simulations of a Northerly Low-Level Jet and Its Impact on Air Quality over Indianapolis, Atmos. Chem. Phys., submitted, 2016.

    Carlton A.M., J. de Gouw, J. L. Jimenez, J. L. Ambrose, S. Brown, K. R. Baker, C. A. Brock, R. C. Cohen, S. Edgerton, C. Farkas, D. Farmer, A. H. Goldstein, L. Gratz, A. Guenther, S. Hunt, L. Jaeglé, D. A. Jaffe, J. Mak, C. McClure, A. Nenes, T. Khoi, V. Nguyen, J. R. Pierce, N. Selin, V, Shah, S. Shaw, P. B. Shepson, S. Song, J. Stutz, J. Surratt, B. J. Turpin, C. Warneke, R. A. Washenfelder, P. O. Wennberg, X. Zhou, “Synthesis of the Southeast Atmosphere Studies: investigating fundamental atmospheric chemistry questions”, Bull. Am. Soc. Meteorol., in press, 2017.

    Simpson, W. R., P. K. Peterson, U. Friess, H. Sihler, U. Platt, C. Moore, K. Pratt, P. B. Shepson, and S. V. Nghiem, Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS spectroscopy, in press, Atmos. Chem. Phys., 17, 9291–9309, 2017.

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