In situ measurements of midlatitude ClO in winter

D. W. Toohey, W. H. Brune, K. R. Chan, J. G. Anderson

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

In situ measurements of ClO in the winter lower stratosphere are presented for six flights of the NASA ER‐2 aircraft from 38°N to 61°N. Enhanced abundances, increasing in severity with date, were observed below 20 km, where HCl and ClONO2 dominate the inorganic chlorine budget. The greatest mixing ratios, over 150 pptv, were encountered on February 20 and 21, 1989, as the vortex experienced a major warming. Although the timing of these ClO enhancements and the evidence that vortex air can reach midlatitudes suggest that heterogeneous conversion of chlorine compounds within the vortex influences chemistry at midlatitudes, the enhancements observed early in the winter could have been caused by unknown chemistry occurring outside the vortex. In either case, photochemical loss of ozone due to catalytic reactions involving ClO at these mixing ratios may be responsible in part for the ozone decreases observed at high latitudes in the northern hemisphere.

Original languageEnglish (US)
Pages (from-to)21-24
Number of pages4
JournalGeophysical Research Letters
Volume18
Issue number1
DOIs
StatePublished - Jan 1991

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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