Evolution of HCL concentrations in the lower stratosphere from 1991 to 1996 following the eruption of Mt. Pinatubo

• Published in: Geophysical research letters Vol. 25; no. 7; pp. 995 - 998
• Main Authors: Webster, C. R., May, R. D., Michelsen, H. A., Scott, D. C., Wilson, J. C., Jonsson, H. H., Brock, C. A., Dye, J. E., Baumgardner, D., Stimpfle, R. M., Koplow, J. P., Margitan, J. J., Proffitt, M. H., Jaeglé, L., Herman, R. L., Hu, H., Flesch, G. J., Loewenstein, M.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01-04-1998; American Geophysical Union
• Subjects: Atmospheric composition. Chemical and photochemical reactions; Earth, ocean, space; Exact sciences and technology; External geophysics; Physics of the high neutral atmosphere; Hydrogen Chlorides; Volcanic eruption; Chemical reaction; Aircraft observation; Stratosphere; Activation; Sulfates; Stratospheric aerosol; Concentration distribution; Heterogeneous reaction
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/98GL00548

In situ measurements of hydrochloric acid in the lower stratosphere reveal that its mean abundance relative to that of total inorganic chlorine (Cly) has evolved upwards from HCl/Cly = 40% in late 1991 to 70% in 1996. This fraction is generally anticorrelated with aerosol surface area concentration, which has been diminishing since the 1991 volcanic eruption of Mt. Pinatubo. Calculations incorporating new laboratory results of faster heterogeneous chemistry show that air parcels with high aerosol loading exposed to temperatures below 205 K can experience enough chlorine activation to drive the HCl/Cly below 50%, but overestimate observed ClO/Cly.