Oregon State University


Cynthia Twohy

Cynthia Twohy photo
Professor (Senior Research)

Discipline: Physics of Oceans and Atmospheres
Secondary Discipline: Ocean Ecology and Biogeochemistry
Phone: 541-737-5690
Fax: 541-737-5039
Email: twohy@coas.oregonstate.edu
Vita or Résumé (PDF)

Research Interests

Aerosol-cloud interactions, climate, marine aerosols, aerosol and cloud physics measurement.

Current Research

Indirect effect (through clouds) of aerosols on climate, Saharan dust impacts on cloud systems, ice clouds


BS, University of California, Davis (Food Science & Technology), 1981
MS, University of Washington (Atmospheric Sciences), 1988
PhD, University of Washington (Atmospheric Sciences), 1992



Twohy, C.H., 1988: Sampling and analysis of cloud droplets by aircraft using a counterflow virtual impactor. M.S. Thesis, University of Washington, Department of Atmospheric Sciences, 133 pp.

Twohy, C.H., 1992: On the size dependence of the chemical properties of cloud droplets: exploratory studies by aircraft. NCAR Cooperative Thesis CT-137, University of Washington (Department of Atmospheric Sciences) and National Center for Atmospheric Research, 239 pp.

Selected refereed:

Twohy, C. H., P. Austin and R. J. Charlson, 1989: Chemical consequences of the initial diffusional growth of cloud droplets: a clean marine case. Tellus, 41B, 51-60.

Twohy, C. H., A. D. Clarke, S. G. Warren, L.F. Radke and R. J. Charlson, 1989: Light absorbing material extracted from cloud droplets and its effect on cloud albedo. J. Geophys. Res., 94, 8623 8631.

Twohy, C.H. and D. Rogers, 1993: Airflow and water drop trajectories at instrument sampling points around the Beechcraft King Air and Lockheed Electra. J. Atmos. Oceanic Technol., 10, 566 578.

Twohy, C. H., P. A. Durkee, B. J. Huebert and R. J. Charlson, 1995: Effects of aerosol particles on the microphysics of coastal stratiform clouds. J. Climate, 8, 773 783.

Twohy, C. H., and J. G. Hudson, 1995: Measurements of cloud condensation nucleus spectra within maritime cumulus cloud droplets: Implications for mixing processes. J. Appl. Meteor., 34, 815-833.

Twohy, C. H., A.J. Schanot and W. A. Cooper, 1997: Measurement of condensed water content in liquid and ice clouds using an airborne counterflow virtual impactor. J. Atmos. Oceanic Tech., 14, 197-202.

Twohy, C.H., 1998: Model calculations and wind tunnel testing of an isokinetic shroud for high speed sampling. Aer. Sci. and Tech., 29, 261-280.

Twohy, C. H., and B. W. Gandrud, 1998: Electron microscope analysis of residual particles from aircraft contrails. Geophys. Res. Lett., 25, 1359-1362.

Twohy, C. H., J. G. Hudson, S. S. Yum, J. R. Anderson, S. K. Durlak, and D. Baumgardner, 2001: Characteristics of cloud nucleating aerosols in the Indian Ocean region. J. Geophys. Res., 106, 28699-28710.

Twohy, C. H., C. F. Clement, B. W. Gandrud, A. J. Weinheimer, T. Campos, D. Baumgardner, W. H. Brune, I. Faloona, D. Tan, G. W. Sachse and S. A. Vay, 2002: Deep convection as a source of new particles in the midlatitude upper troposphere. J. Geophys. Res., 107, 4560, doi: 10.1029/2001JD000323.

Twohy, C. H., J. W. Strapp, and M. Wendisch, 2003: Performance of a counterflow virtual impactor in the NASA Icing Research Tunnel. J. Atmos. Ocean. Tech., 20, 781-790.

Twohy, C. H., M. D. Petters, J. R. Snider, B. Stevens, W. Tahnk, M. Wetzel, L. Russell and F. Burnet, 2005: Evaluation of the aerosol indirect effect in marine stratocumulus clouds: droplet number, size, liquid water path and radiative impact. J. Geophys. Res., 110, D08203, doi:10.1029/2004JD005116.

Twohy, C. H. and M. R. Poellot, 2005: Chemical characteristics of ice residual nuclei in anvil cirrus clouds: implications for ice formation processes Atmos. Chem. Phys., SRef-ID: 1680-7324/acp/2005-5-2289.

Twohy, C. H., J. R. Anderson, and P. A. Crozier, 2005: Nitrogenated organic aerosols as cloud condensation nuclei. Geophys. Res. Lett., 32, L19805, doi:10.1029/2005GL023605.

Twohy, C. H., and J. R. Anderson, 2008: Droplet nuclei in non-precipitating clouds: Composition and size matter. Environ. Res. Lett., 3, doi: 10.1088/1748-9326/3/4/045002 (invited paper).

Twohy, C. H., Kreidenweis, T. Eidhammer, E. V. Browell, A. J. Heymsfield, A.R. Bansemer, B. E. Anderson, G. Chen, S. Ismail, P. J. DeMott and S. Van den Heever, 2009: Saharan dust particles nucleate droplets in eastern Atlantic clouds. Geophys. Res. Lett., 36, L01807, doi:10.1029/2008GL035846 (selected as a Research Highlight in Nature and Nature Geoscience).

Twohy, C. H., J. A. Coakley, Jr., and W. R. Tahnk, 2009: The effect of changes in relative humidity on aerosol scattering near clouds. J. Geophys. Res., 114, D05205, doi:10.1029/2008JD010991.

Twohy, C. H., P. J. DeMott, K. A. Pratt, R. Subramanian, G. L. Kok, S. M. Murphy, T. Lersch, A. J. Heymsfield, Z. Wang, K. A. Prather, and J. H. Seinfeld, 2010: Relationships of biomass burning aerosols to ice in orographic wave clouds. J. Atmos. Sci, 67, 2437-2450, doi: 10.1175/2010JAS3310.1.

Twohy, C. H., J. R. Anderson, D. W. Toohey, M. Andrejczuk, A. Adams, M. Lytle, R. C. George, R. Wood, P. Saide, S. Spak, P. Zuidema, and D. Leon, 2013: Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific ocean, Atmos. Chem, Phys, 13, 2541-2562, doi:10.5194/acpd-13-2541-2013.

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