Atmospheric Physics and Chemistry; Aerosol Microphysics
Faculty Member, Atmospheric Sciences Research Center
Adjunct Faculty, Department of Earth and Atmospheric Sciences
Office: CESTM-L208
Phone: (518) 437-8767; Fax: (518) 437-8711
Email: yfq@asrc.cestm.albany.edu
Homepage: http://www.albany.edu/~yfq
B.S. (Atmospheric Sciences), 1991, Peking University, China
M.S. (Atmospheric Physics), 1994, Institute of Atmospheric Physics, China
M.S. (Atmospheric Sciences), 1996, University of California at Los Angeles
Ph. D. (Atmospheric Sciences), 1998, University of California at Los Angeles
Research Interests:
Fundamental mechanism of ultrafine aerosol formation; Ion-mediated nucleation; Role of ions, sulfuric acid, and organics in aerosol formation and evolution; Advanced particle microphysics model development and application; Sun-Earth connection; Aerosol-related problems.
In recent years, increasing attention has been focused on the influence of atmospheric aerosols on climate and atmospheric chemistry as well as the adverse health effects associated with fine particles. The effects of aerosols on health, chemistry and climate are sensitive to particle size and concentration, which are influenced significantly by nucleation processes. However, the fundamental mechanism of new particle formation in the atmosphere remains poorly understood despite intensive research over the past several decades. A clear understanding of the formation mechanisms and processes controlling the properties of atmospheric aerosols is critical in assessing of the potential climatic/environmental/health effects associated with particle pollution, and in finding solutions to these problems.
Our primary research interests are theoretical studies and numerical simulations of processes controlling the formation, evolution, and properties of atmospheric aerosols. We seek to achieve a better understanding of the key mechanisms determining the variability of condensation nuclei (CN) and cloud condensation nuclei (CCN) abundance in the atmosphere. We have developed an advanced particle microphysics (APM) model which is capable to simulate the microphysics of a multi-type, size-dispersed, composition-resolved aerosol system. The APM model is built to be flexible, modular, and efficient, and can be easily reconfigured to study various aerosol-related problems. One of the unique features of the APM model is the inclusion of size-resolved electrical charge effects. The APM model has been successfully applied to applied to analyze a number of specific, and unusual, aerosol data sets.
We have proposed a new formation mechanism of atmospheric aerosols - ion-mediated nucleation (IMN). The charged molecular clusters, condensing around natural air ions, can grow significantly faster than corresponding neutral clusters, and thus can preferentially achieve stable, observable sizes. The APM model incorporates the complex charged and neutral processes from molecular size to nanometer scale that define IMN. The IMN theory can physically explain the enhanced growth rate of sub-nanometer clusters, and seems to account consistently for ultrafine aerosol formation in jet plumes, in clean continental air and in marine boundary layer, as well as for the observed diurnal variation in the atmospheric mobility spectrum.
The IMN theory and numerical simulations provide certain theoretical support for a proposed European experiment called CLOUD at CERN, the European particle physics laboratory in Geneva. The CLOUD project is intended to test the cosmic ray-aerosol-cloud hypothesis and involves prominent scientists from many European countries. Dr. Yu has been invited to join the CLOUD investigation team.
The short-term research objectives include: (1) to validate the schemes to calculate several key parameters controlling sub-nanometer cluster growth (accommodation coefficient, enhancement factor due to the electrostatic effect, etc.); (2) to study the dependence of nucleation rate on ionization rate, sulfuric acid vapor concentration, ambient aerosol concentration, and ambient conditions (temperature, relative humidity, etc.); (3) to deduce empirical formulas of ion-mediated nucleation rates for general use; (4) to investigate the contribution of certain low volatile organics to CN growth; (5) to analyze various field and laboratory data relevant to ultrafine particle formation and growth; (6) to investigate whether galactic cosmic ray variations that result from variations in solar activity can affect low cloud properties, and if so, to elucidate the physical mechanism and the magnitude of such effects; (7) more ...
The long-term research objective is to develop an efficient and practical aerosol microphysics module using the APM model as a basis, and couple the module to chemical transfer models (both regional and global scale) to study various aerosol related problems. The aerosol module will resolve the size and composition of particles for a range of types (including internal and external mixtures), and will contain empirical formulas (developed through detailed studies) to simplify microphysics processes for efficiency.
Selected Publications
Kärcher, B., F. Yu, F. P. Schröeder, and R. P. Turco, Ultrafine aerosol particles in aircraft plumes: Analysis of growth mechanisms, Geophys. Res. Lett., 25, 2793-2796, 1998.
Kärcher, B., R. P. Turco, F. Yu, M.Y. Danilin, D. K. Weisenstein, R. C. Miake-Lye, and R. Busen, On the unification of aircraft ultrafine particle emission data, J. Geophy. Res., 105, 29,379-29,386, 2000.
Turco, R. P., and F. Yu, Aerosol invariance in expanding coagulating plumes, Geophys. Res. Lett., 24, 1223-1226, 1997.
Turco, R. P., and F. Yu, Particle size distribution in an expanding plume undergoing simultaneous coagulation and condensation, J. Geophy. Res., 104, 19,227-19,242, 1999.
Yu, F., and R. P. Turco, The role of ions in the formation and evolution of particles in aircraft plumes, Geophys. Res. Lett., 24, 1927-1930, 1997.
Yu, F., and R. P. Turco, Contrail formation and impacts on aerosol properties in aircraft plumes: Effects of fuel sulfur content, Geophys. Res. Lett., 25, 313-316, 1998a.
Yu, F., and R. P. Turco, The formation and evolution of aerosols in stratospheric aircraft plumes: Numerical simulations and comparisons with observations, J. Geophy. Res. 103, 25,915-25,934, 1998b.
Yu, F., and R. P. Turco, Evolution of aircraft-generated volatile particles in the far wake regime: Potential contributions to ambient CCN/IN, Geophys. Res. Lett., 26, 1703-1706, 1999.
Yu, F., and R. P. Turco, Ultrafine Aerosol Formation via Ion-Mediated Nucleation, Geophys. Res. Lett., 27, 883-886, 2000.
Yu, F. and R. P. Turco, From molecular clusters to nanoparticles: The role of ambient ionization in tropospheric aerosol formation, J. Geophys. Res., 106, 4797-4814, 2001.
Yu, F., and R. P. Turco, On the contribution of lightning to ultrafine aerosol formation, Geophys. Res. Lett., 28, 155-158, 2001.
Yu, F., R. P. Turco, and B. Kärcher, The possible role of organics in the formation and evolution of ultrafine aircraft particles, J. Geophy. Res., 104, 4079-4087, 1999.
Yu, F., R. P. Turco, B. Kärcher, and F. P. Schröeder, On the mechanisms controlling the formation and properties of volatile particles in aircraft wakes, Geophys. Res. Lett., 25, 3839-3842, 1998.
(Last updated: August, 28, 2001)