Steven Brown
Adjoint Professor

Office: Cristol 153
Phone: 303-497-6306


Ph.D., University of Wisconsin-Madison, 1996
B.A., Dartmouth College, 1989

Awards and Honors

Presidential Early Career Award for Scientists and Engineers (2002)
CIRES Outstanding Performance Award (2003)

Heterogeneous nitrogen oxide chemistry & halogen activation

Gas-particle reactions of nitrogen oxides are key to the regulation of atmospheric oxidant burdens, but they remain rather poorly understood. For example, recent NOAA led field work led to the discovery of nitryl chloride (ClNO2), a major source of chlorine to the atmosphere, produced by heterogeneous nitrogen oxide chemistry. We have developed key instrumentation and led major field intensives in New EnglandTexas and the Gulf CoastNew York CityCalifornia and Colorado to investigate these issues.

Nocturnal biogenic VOC oxidation. 

Biogenic VOC from terrestrial vegetation (e.g., isoprene, monoterpenes) and biogenic marine sulfur compounds (e.g., dimethyl sulfide, DMS) undergo rapid nocturnal degradation in the presence of the nitrate radical, NO3. Since NO3 is derived from NOx, an anthropogenic pollutant, these oxidative processes represent an anthropogenic perturbation of a biogenic atmospheric input. These perturbations can have important consequences, such as the formation of organic and sulfate aerosol that affect Earth's climate. These processes have been studied through recent field studies from ships (New England 2002), aircraft (New England 2004Texas 2006), at the SAPHIRchamber in Jülich, and at the 2011 BEACHON-RoMBAS campaign at Manitou Forest in Colorado. Recent experiments include aircraft and ground based measurements in the southeast U.S. during the SENEX and SOAS campaigns.

Oil and gas emissions, wintertime ozone. 

The environmental impacts of the recent increase in production of oil and natural gas in North America are an important current issue. Shale gas basins in both Utah and Wyoming have recently experienced ozone air quality episodes, but only during the winter season. The mechanism for this ozone formation remains unclear, but may be related in part to oxidant formation through heterogeneous nitrogen oxide reactions. Recent field campaigns in both Utah and Colorado's front range have investigated this phenomenon along with emissions of NOxand VOCs from oil and gas activities.

Hagen, C.L., B.C. Lee, I.S. Franka, J.L. Rath, T.C.VandenBoer, J.M. Roberts, S.S. Brown, and A.P. Yalin,
Cavity ring-down spectroscopy sensor for detection of hydrogen chloride. Atmos. Meas. Tech., 2014. 7(2): p. 345-

Washenfelder, R.A., J.M. Flores, C.A. Brock, S.S. Brown, and Y. Rudich, Broadband measurements of aerosol extinction in the ultraviolet spectral region. Atmos. Meas. Tech., 2013. 6: p. 861-877

Wagner, N.L., T.P. Riedel, C.J. Young, R. Bahreini, C.A. Brock, W.P. Dubé, S.Kim, A.M. Middlebrook, F. Öztürk, J.M. Roberts, R. Russo, B. Sive, R. Swarthout, J.A. Thornton, T.C. VandenBoer, Y. Zhou, and S.S. Brown, N2O5 uptake coefficients and nocturnal NO2 removal rates determined from ambient wintertime measurements. J. Geophys. Res., 2013. 118 (16): p. 9331-9350

Vicars, W.C., S. Morin, J. Savarino, N.L. Wagner, J. Erbland, E. Vince, J.M.F. Martins, B.M. Lerner, E.J. Williams, and S.S. Brown, Spatial and diurnal
variability in reactive nitrogen oxide chemistry as reflected in the isotopic composition of atmospheric nitrate: Results from the CalNex 2010 field study.
J.Geophys. Res., 2013. 118 (18): p. 10567-10588

 Riedel, T.P., N.L. Wagner, W.P. Dubé, A.M. Middlebrook, C.J. Young, F. Öztürk,R. Bahreini, T.C. VandenBoer, D.E. Wolfe, E.J. Williams, J.M. Roberts, S.S.Brown, and J.A. Thornton,
Chlorine activation within urban and power plant plumes: vertically resolved ClNO2 and Cl2 measurements from a tall tower in a polluted continental setting. J. Geophys. Res., 2013. 118(15): p. 8702-8715