Atmospheric Ion-induced Aerosol Nucleation
- 238 Downloads
Ion-induced nucleation has been suggested to be a potentially important mechanism for atmospheric aerosol formation. Ions are formed in the background atmosphere by galactic cosmic rays. A possible connection between galactic cosmic rays and cloudiness has been However, the predictions of current atmospheric nucleation models are highly uncertain because the models are usually based on the liquid drop model that estimates cluster thermodynamics based on bulk properties (e.g., liquid drop density and surface tension). Sulfuric acid (H2SO4) and water are assumed to be the most important nucleating agents in the free troposphere. Measurements of the molecular thermodynamics for the growth and evaporation of cluster ions containing H2SO4 and H2O were performed using a temperature-controlled laminar flow reactor coupled to a linear quadrupole mass spectrometer as well as a temperature-controlled ion trap mass spectrometer. The measurements were complemented by quantum chemical calculations of the cluster ion structures. The analysis yielded a complete set of H2SO4 and H2O binding thermodynamics extending from molecular cluster ions to the bulk, based on experimental thermodynamics for the small clusters. The data were incorporated into a kinetic aerosol model to yield quantitative predictions of the rate of ion-induced nucleation for atmospheric conditions. The model predicts that the negative ion-H2SO4-H2O nucleation mechanism is an efficient source of new particles in the middle and upper troposphere.
Keywordsion-induced nucleation aerosol clusters ions particles atmosphere sulfuric acid
Unable to display preview. Download preview PDF.
- Bonn, B. and Moortgart, G. K.: 2003, ‘Sesquiterpene ozonolysis: Origin of atmospheric new particle formation from biogenic hydrocarbons’, Geophys. Res. Lett. 30, 10.1029/2003GL017000.Google Scholar
- Clarke, A. D., Varner, J. L., Eisele, F., Mauldin, R. L., Tanner, D., and Litchy, M.: 1998, ‘Particle production in the remote marine atmosphere: Cloud outflow and subsidence during ACE 1, J. Geophys. Res. 103, 16,397–16,409.Google Scholar
- Eichkorn, S., Wilhelm, S., Aufmhoff, H., Wohlfrom, K. H., and Arnold, F.: 2002, ‘Cosmic ray-induced aerosol-formation: First observational evidence from aircraft-based ion mass spectrometer measurements in the upper troposphere’, Geophys. Res. Lett. 29, 10.1029/2002GL015044.Google Scholar
- Kazil, J., and Lovejoy, E. R.: 2004, ‘Tropospheric ionization and aerosol production: A model study’, J. Geophys. Res. 109, 10.1029/2004JD004852.Google Scholar
- Lovejoy, E. R., Curtius, J., Froyd, K. D.: 2004, ‘Atmospheric ion-induced nucleation of sulphuric acid and water’, J. Geophys. Res. 109, 10.1029/2003JD004460.Google Scholar
- Yu, F.: 2002, ‘Altitude variations of cosmic ray induced production of aerosols: Implications for global cloudiness and climate’, J. Geophys. Res. 107, 10.1029/2001JA000248.Google Scholar