Tropospheric Composition

What controls the chemical composition of the polluted and remote atmosphere? How do emissions from the biosphere and from human activity interact to determine the overall chemical properties of our atmosphere? We carry out targeted field experiments to study these questions and provide fundamental tests of current atmospheric models.

Example Publications

Millet, D.B., A.H. Goldstein, R. Holzinger, B. Williams, J.D. Allan, J.L. Jimenez, D.R. Worsnop, J.M. Roberts, A.B. White, R.C. Hudman, I.T. Bertschi, and A. Stohl (2006), Chemical characteristics of North American surface-layer outflow: Insights from Chebogue Point, Nova Scotia, J. Geophys. Res., 111, D23S53, doi:10.1029/2006JD007287.

Millet, D.B., A.H. Goldstein, J.D. Allan, T.S. Bates, H. Boudries, K.N. Bower, H. Coe, Y. Ma, M. McKay, P.K. Quinn, A. Sullivan, R.J. Weber, and D.R. Worsnop (2004), Volatile organic compound measurements at Trinidad Head, California during ITCT 2K2: Analysis of sources, atmospheric composition and aerosol residence times, J. Geophys. Res., 109, D23S16, doi:10.1029/2003JD004026.

Cycling of Organic Carbon

Organic carbon plays a key role in atmospheric chemistry. In the gas phase, volatile organic compounds (VOCs) are precursors of tropospheric ozone and secondary organic aerosol, and drive tropospheric oxidant chemistry. In the condensed phase, organic carbon (OC) is a major fraction of atmospheric aerosol, and affects human health, visibility and climate. Major gaps exist in our understanding of the sources, composition, and chemistry of atmospheric organic carbon, and how they might change in the future. One goal of our research is to improve understanding of atmospheric organic chemistry, in both the gas and condensed phase.

Example Publications

Millet, D.B., N.M. Donahue, S.N. Pandis, A. Polidori, C.O. Stanier, B.J. Turpin, and A.H. Goldstein (2005), Atmospheric volatile organic compound measurements during the Pittsburgh Air Quality Study: Results, interpretation and quantification of primary and secondary contributions, J. Geophys. Res., 110, D07S07, doi:10.1029/2004JD004601.

Biosphere-Atmosphere Exchange

How does Earth's biosphere regulate the chemical properties of the atmosphere? How will biogenic emissions change in the future? The terrestrial biosphere is a major source of reactive trace gases and particles to the global atmosphere -- these emissions interact in complex ways with anthropogenic pollutants. Understanding biogenic emissions is a prerequisite to quantifying the extent of human impact on the atmosphere and predicting future change.

Example Publications

Millet, D.B., D.J. Jacob, K.F. Boersma, T.-M. Fu, T.P. Kurosu, K. Chance, C.L. Heald, and A. Guenther (2007), Spatial distribution of isoprene emissions from North America derived from formaldehyde column measurements by the OMI satellite sensor, J. Geophys. Res., doi:10.1029/2007JD008950, in press.

Emissions Mapping

Climate and air quality modeling requires a process-level understanding of the emissions of the controlling atmospheric constituents. New satellite measurements of atmospheric composition offer unprecedented top-down constraints on trace gas and aerosol sources; the capabilities of these data are just beginning to be explored. Combining these space-borne data with in situ (surface and aircraft) measurements can provide a quantitative test of bottom-up understanding.

Example Publications

Millet, D.B., D.J. Jacob, K.F. Boersma, T.-M. Fu, T.P. Kurosu, K. Chance, C.L. Heald, and A. Guenther (2007), Spatial distribution of isoprene emissions from North America derived from formaldehyde column measurements by the OMI satellite sensor, J. Geophys. Res., doi:10.1029/2007JD008950, in press.

Millet, D.B., D.J. Jacob, S. Turquety, R.C. Hudman, S. Wu, A. Fried, J. Walega, B.G. Heikes, D.R. Blake, H.B. Singh, B.E. Anderson, and A.D. Clarke (2006), Formaldehyde distribution over North America: Implications for satellite retrievals of formaldehyde columns and isoprene emission, J. Geophys. Res., 111, D24S02, doi:10.1029/2005JD006853.

Millet, D.B., and A.H. Goldstein (2004), Evidence of continuing methylchloroform emissions from the United States, Geophys. Res. Lett., 31, L17101, doi:10.1029/2004GL020166.