Observations of the decay of the El Chichon stratospheric aerosol cloud in Antarctica

Balloonborne measurements of stratospheric aerosol in the late October ‐ early November period in 1983, 1984 and 1985 indicate that the sulfuric acid aerosol which formed in the stratosphere following the eruption of El Chichón in 1982, and which was subsequently transported to the polar regions, decayed over Antarctica with an exponential decay time of about one year, in reasonable agreement with extensive measurements at Laramie during this period. These results suggest that the increased aerosol burden over Antarctica, which occurred as a result of the El Chichón eruption, cannot be directly involved in the precipitous decline of stratospheric ozone in Antarctica since 1982, although indirect effects cannot be ruled out.