University of California, Riverside

Environmental Sciences

Roya Bahreini

Roya Bahreini

Roya Bahreini Photo

Associate Professor of Atmospheric Science

Academic Degrees:

  • Ph.D., California Institute of Technology, 2005
  • M.S., California Institute of Technology, 2003
  • B.S., University of Maryland, College Park, 1999

Selected Awards and Honors:

  • UCR Regents’ Faculty Development Award- 2016
  • NSF CAREER Award, 2015
  • Thomson Reuters Highly Cited Researchers, 2014
  • The World's Most Influential Scientific Minds, 2014
  • CO-LABS Governor’s Award for High-Impact Research, 2012
  • University of Colorado- CIRES Outstanding Performance Award in Science and Engineering, 2011
  • University of Colorado- CIRES Visiting Scholar Fellowship, June 2005-2007
  • NASA Group Achievement Award for CRYSTAL-FACE Field Project, 2003


  • Airborne, ground-based, and laboratory measurements of aerosol composition and microphysical properties
  • Air quality
  • Aerosol direct- and indirect-effects on climate

Recent News:

  • Justin Min has been selected to participate in DOE's Science Undergraduate Laboratory Internship program. He'll be working at Brookhaven National Lab, starting in Jan. 2018. Congratulations Justin!
  • Stephen was recognized as a winner in the AAAR-2017 Student Poster Competition. Well done Stephen!
  • Alex has received the Albert Marsh Environmental Sciences Travel Scholarship. Congratulations Alex!
  • Stephen and Alex have received travel/student support to present at the annual AAAR meeting in Raleigh, NC in Oct.!
  • Aug. 2017: Alex’s paper has been picked up in the media:
  • 21 July, 2017: Alex’s paper on his analysis of the Salton Sea samples is published in EST. Congratulations Alex!
  • 27 Sep. 2016: Kennedy’s paper on the influence of the Denver Cyclone on air quality in the Front Range is published. Congratulations Kennedy!
  • 23 Sep. 2016: Alex is awarded a scholarship from the Association of Environmental Professionals- Inland Empire Chapter. Congrats Alex!
  • 12 Sep. 2016: Justin’s paper on aerosol optical extinction during FRAPPÉ is published. Congratulations Justin!
  • 11 March 2016: Kennedy successfully defended his Master’s Thesis! Well-done Kennedy!

Past and Current Research:

  • Vehicle Emission Measurements
    • Online aerosol extinction measurements of vehicular exhaust using a cavity phase-shift spectrometer (CAPS-PMex)
  • Ambient ground-based measurements in Mira Loma, CA
      • Online aerosol composition and optical extinction measurements in Mira Loma, CA, using a compact aerosol mass spectrometer (mAMS) and a cavity phase-shift spectrometer (CAPS-PMex)
      • Offline composition analysis of aerosol samples collected in Mira Loma and Riverside by gas chromatography/mass spectrometry (GC-MS) and High Performance Liquid Chromatography (HPLC)

    Click here for pictures from the sampling site

  • Airborne measurements in Colorado during FRAPPE
      • Online aerosol composition and optical extinction measurements on board the NSF C130 aircraft, using a compact aerosol mass spectrometer (mAMS) and a cavity phase-shift spectrometer (CAPS-PMex)

    Click here for pictures from FRAPPE

  • Laboratory studies of aerosol chemical and optical properties
    • Smog chamber generation of secondary organic aerosol from various precursors and under different conditions
    • Aerosol composition measurements by mAMS and optical extinction, scattering and absorption measurements by CAPS-PMex and PAX
    Soil and Aerosol Composition Measurements at Salton Sea
    • Offline, ICP-MS analysis of trace elements from size-dependent aerosol filter samples collected by a MOUDI at Salton City and Bombay Beach
    • Trace metal characterization of arid soil and playa around Salton Sea by XRF and ICP-MS

    Click here for pictures from the sampling site

Research Group:

  • Current Students
    • Past Students
      • Kennedy T. Vu, Environmental Toxicology, M.S., March 2016
      • Pavan Rami, Undergraduate in Environmental Sciences
      • Dominic Chan, Undergraduate in Environmental Sciences
    • Future Group Members
      • Currently seeking a highly motivated M.S. or Ph.D. student, interested in field and/or laboratory observations of aerosol chemical and optical properties; please email ( if interested.

    Graduate Program Affiliations and Research Focus Areas:

    Courses Taught:

    • ENSC 102- Introductory Atmospheric Science
    • ENSC/ENTX/CHEM 135- Chemistry of Clean and Polluted Atmosphere
    • ENSC/ENTX 200- Fate and Transport of Chemicals in the Environment
    • ENSC/GEO 265- Special Topics in Earth and Environmental Sciences: Aerosol Physics and Dynamics
    • ENSC/CHEM/ENTX 245: Chemistry and Physics of Aerosols

    Selected Publications:

    (Supervised *Graduate Student, ǂVisiting Scholar)

    • Frie, A.L.*, J.H. Dingle*, S.C. Ying, R. Bahreini, The Effect of a Receding Saline Lake (The Salton Sea) on Airborne Particulate Matter Composition, Environ. Sci. Technol., 51 (15) DOI: 10.1021/acs.est.7b01773, 2017.
    • Vu, K.T.*, J.H. Dingle*, R. Bahreini, P.J. Reddy, E.C. Apel, T.L. Campos, J.P. DiGangi, G.S. Diskin, A. Fried, S.C. Herndon, A.J. Hills, R.S. Hornbrook, G. Huey, L. Kaser, D.D. Montzka, J.B. Nowak, S.E. Pusede, D. Richter, J.R. Roscioli, G.W. Sachse, S. Shertz, M. Stell, D. Tanner, G. Tyndall, J. Walega, P. Weibring, A.J. Weinheimer, G. Pfister, F. Flocke, Impacts of the Denver Cyclone on Regional Air Quality and Aerosol Formation in the Colorado Front Range during FRAPPÉ 2014, Atmos. Chem. Phys., 16, doi:10.5194/acp-16-12039-2016, 2016.
    • Dingle, J.H.*, K.T. Vu*, R. Bahreini, E.C. Apel, T.L. Campos, F. Flocke, A. Fried, S. Herndon, A.J. Hills, R.S. Hornbrook, G. Huey, L. Kaser, D.D. Montzka, J.B. Nowak, M. Reeves, D. Richter, J.R. Roscioli, S. Shertz, M. Stell, D. Tanner, G. Tyndall, J. Walega, P. Weibring, A. Weinheimer, Aerosol Optical Extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 Summertime Filed Campaign, Colorado, U.S.A., Atmos. Chem. Phys., 16, doi:10.5194/acp-16-11207-2016, 2016.
    • Chang, W.L., S.S. Brown, J. Stutz, A.M. Middlebrook, R. Bahreini, N.L. Wagner, W.P. Dube, I.B. Pollack, T.B. Ryerson, N. Riemer, Evaluating N2O5 heterogeneous hydrolysis parameterizations for CalNex 2010, J. Geophys. Res- Atmospheres, DOI: 10.1002/2015JD024737, 2016.
    • Bahreini, R, J. Xue, K. Johnson, T. Durbin, D. Quiros, S. Hu, T. Huai, A. Ayala, H. Jung, Characterizing emissions and optical properties of particulate matter from PFI and GDI light-duty gasoline vehicles. J. Aerosol Science, 90, 144-153, DOI.1016/j.jaerosci.2015.08.011, 2015.
    • Fast, J.D., J. Allan, R. Bahreini, J. Craven, L. Emmons, R. Ferrare, P.L. Hayes, A. Hodzic, J. Holloway, C. Hostetler, J.L. Jimenez, H. Jonsson, S Liu, Y. Liu, A. Metcalf, A. Middlebrook, J. Nowak, M. Pekour, A. Perring, L. Russell, A. Sedlacek, J. Seinfeld, A. Setyan, J. Shilling, M. Shrivastava, S. Springston, C. Song, R. Subramanian, J.W. Taylor, V. Vinoj, Q. Yang, R.A. Zaveri, Q. Zhang, Modeling regional aerosol and aerosol precursor variability over California and its sensitivity to emissions and long-range transport during the 2010 CalNex and CARES campaigns, Atmos. Chem. Phys., DOI: 0.5194/acp-14-10013-2014, 2014.
    • Schiferl, L.D., C.L. Heald, J.B. Nowak, J.S. Holloway, J.A. Neuman, R. Bahreini, I.B. Pollack, T.B. Ryerson, C. Wiedenmyer, J.G. Murphy, An investigation of ammonia and inorganic particulate matter in California during the CalNex campaign, J. Geophys. Res., DOI: 10.1002/2013JD020765, 2014.
    • Ӧztürk, F.ǂ, R. Bahreini, N.L. Wagner, W.P. Dube, C.J. Young, S.S. Brown, C.A. Brock, I.M. Ulbrich, J.L. Jimenez, O.R. Cooper, A.M. Middlebrook, Vertically resolved chemical characteristics and sources of submicron aerosols measured on a tall tower in a suburban area near Denver, Colorado in winter, DOI: 10.1002/2013JD019923, 2013.
    • Craven, J.S., A.R. Metcalf, R. Bahreini, A.M. Middlebrook, P.L. Hayes, H.T. Duong, A. Sorooshian, J.L. Jimenez, R.C. Flagan, J.H. Seinfeld, Los Angeles Basin airborne organic aerosol characterization during CalNex, J. Geophys. Res., DOI: 10.1002/jgrd.50853, 2013.
    • Brown, S.S., W.P. Dube, R. Bahreini, A.M. Middlebrook, C.A. Brock, C. Warneke, J.A. de Gouw, R.A. Washenfelder, E. Atlas, J. Peischl, T.B. Ryerson, J.S. Holloway, J.P. Schwarz, R. Spackman, M. Trainer, D.D. Parrish, F.C. Fehsenfeld, and A.R. Ravishankara, Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft profiles in Houston, TX, Atmos. Chem. Phys. 13, 11317-11337, 2013.
    • Lack, D.A., R. Bahreini, J.M. Langridge, J.B. Gilman, A.M. Middlebrook, Brown carbon absorption linked to organic mass tracers in biomass burning particles, Atmos. Chem. Phys.,13, 10.5194/acp-13-2415-2013, 2013
    • Lack, D.A., J.M. Langridge, R. Bahreini, C.D. Cappa, A.M. Middlebrook, J.P. Schwarz, Brown carbon and internal mixing in biomass burning particles, Proc. Natl. Acad. Sci. USA, 109 (37), 10.1073/pnas.1206575109, 2012.
    • Bahreini, R., A.M. Middlebrook, C.A. Brock, J.A. de Gouw, S.A. McKeen, L.R. Williams, K.E. Daumit, A.T. Lambe, P. Massoli, M.R. Canagaratna, R. Ahmadov, A.J. Carrasquillo, E.S. Cross, B. Ervens, J.S. Holloway, J.F. Hunter, T.B. Onasch, I.B. Pollack, J.M. Roberts, T.B. Ryerson, C. Warneke, P. Davidovitz, D.R. Worsnop, J.H. Kroll, Mass spectral analysis of organic aerosols formed downwind of the Deepwater Horizon oil spill, Environ. Sci. Technol., 46 (15), 10.1021/es301691k, 2012.
    • Nowak, J.B., J. A. Neuman, R. Bahreini, A. M. Middlebrook, J. S. Holloway, S. A. McKeen, D. D. Parrish, T. B. Ryerson, M. Trainer, Ammonia sources in the California South Coast Air Basin and their impact on ammonium nitrate formation, Geophys. Res. Lett., doi:10.1029/2012GL051197, 2012. (Selected as “EOS Research Highlight”)
    • Bahreini, R., A.M. Middlebrook, J.A. de Gouw, C. Warneke, M. Trainer, C.A. Brock, H. Stark, S.S. Brown, W.P. Dube, J.B. Gilman, K. Hall, J.S. Holloway, W.C. Kuster, A.E. Perring, A.S.H. Prevot, J.P. Schwarz, J.R. Spackman, S. Szidat, N.L. Wagner, R.J. Weber, P. Zotter, D.D. Parrish, Gasoline emissions dominate over diesel information of secondary organic aerosol mass, Geophys. Res. Lett., doi:10.1029/2011GL050718, 2012. (Selected as “GRL Editor’s Highlight” and “EOS Research Highlight”)
    • Langridge, J. M., D. A. Lack, C. A. Brock, R. Bahreini, A. M. Middlebrook, J. A. Neuman, J. B. Nowak, A. E. Perring, J. P. Schwarz, J. R. Spackman, J. S. S. Holloway, I. B. B. Pollack, T. B. B. Ryerson, J. M. M. Roberts, C. Warneke, J. A. de Gouw, M. K. Trainer, and D. M. Murphy, Evolution of aerosol properties impacting visibility and direct climate forcing in an ammonia-rich urban environment, J. Geophys. Res.- Atmosphere, doi:10.1029/2011JD017116, 2012.
    • de Gouw, J.A., A.M. Middlebrook, C. Warneke, R. Ahmadov, E.L. Atlas, R. Bahreini, D.R. Blake, C.A. Brock, J. Brioude, D.W. Fahey, F.C. Fehsenfeld, J.S. Holloway, M. Le Henaff, R.A. Lueb., S.A. McKeen, J.F. Meagher, D.M. Murphy, C. Paris, D.D. Parrish, A.E. Perring, I.B. Pollack, A.R. Ravishankara, A.L. Robinson, T.B. Ryerson, J.P. Schwarz. J.R. Spackman, A. Srinivasan, L.A. Watts, Organic Aerosol Formation Downwind from the Deepwater Horizon Oil Spill, Science, 331, 1295-1299, 2011.
    • Bahreini, R., B. Ervens, A.M. Middlebrook, C. Warneke, J.A. de. Gouw, P.F. DeCarlo, J.L. Jimenez, C.A. Brock, J.A. Neuman, T.B. Ryerson, H. Stark , E. Atlas, J. Brioude, A. Fried, J.S. Holloway, J. Peischl, D. Richter, J. Walega, P. Weibring, A.G. Wollny, F.C. Fehsenfeld , Organic Aerosol Formation in Urban and Industrial Plumes near Houston and Dallas, TX. J. Geophys. Res.- Atmospheres, doi:101.1029/2008011493, 2009.
    • Bahreini, R., E.J. Dunlea, B.M. Matthew, C. Simons, K.S. Docherty, P.F. DeCarlo, J.L. Jimenez, C.A. Brock, A.M. Middlebrook, Design and Operation of a Pressure-controlled inlet for airborne sampling with an aerodynamic aerosol lens. Aerosol Sci. Technol., 42 (6), doi: 10.1080/02786820802178514, 2008.
    • Bahreini, R., M.D. Keywood, N.L. Ng, V. Varutbangkul, S. Gao, R.C. Flagan, J.H. Seinfeld, D.R. Worsnop, Measurements of Secondary Organic Aerosol (SOA) from oxidation of cycloalkenes, terpenes, and m-xylene using the Aerodyne Aerosol Mass Spectrometer, Environ. Sci. Technol., 39 (15), 10.1021/es048061a, 2005.
    • Bahreini, R., J.L. Jimenez, J. Wang, J.T. Jayne, D.R. Worsnop, R.C. Flagan, J.H. Seinfeld, Aircraft-based aerosol size and composition measurements during ACE-Asia using an Aerodyne Aerosol Mass Spectrometer, J. Geophys. Res.- Atmospheres, 108, D23, 8645, doi:10.1029/2002JD003226, 2003.
    • O'Dowd, C., J.L. Jimenez, R. Bahreini, R.C. Flagan, J.H. Seinfeld, K. Hameri, L. Pirjola, M. Kulmala, S.G. Jennings, T. Hoffmann, Marine aerosol formation from biogenic iodine emissions. Nature, 417: 632-636, 2002.


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    Geology 2460

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