The evolution of CLO and NO along air parcel trajectories

M. R. Schoeberl, A. R. Douglass, R. S. Stolarski, P. A. Newman, L. R. Lait, D. Toohey, L. Avallone, J. G. Anderson, W. Brune, D. W. Fahey, K. Kelly

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Back trajectory analysis of Arctic and Antarctic aircraft data reveals that high ClO concentrations are associated with predicted polar stratospheric cloud (PSCs) encounters. The ClO concentrations within the Arctic and Antarctic polar vortices vary widely but appear to be inversely related to parcel solar exposure since the last PSC interaction. These results imply that production of NOx from HNO3 photolysis and reaction with OH is the mechanism, for the loss of chlorine radicals through the reformation of chlorine nitrate. Highly denitrified air parcels show no change in ClO with solar exposure. The recovery process is quantitatively duplicated using a model of chemistry along trajectories. Although PSC processing is the primary mechanism for producing elevated ClO amounts, back trajectories apparently unperturbed by PSC's also show slightly elevated ClO levels in 1992 compared to Arctic 1989 and Antarctic 1987 measurements presumably due to the presence of Pinatubo aerosol.

Original languageEnglish (US)
Pages (from-to)2511-2514
Number of pages4
JournalGeophysical Research Letters
Issue number22
StatePublished - Nov 19 1993

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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