Correlations between ozone loss and volcanic aerosol at altitudes below 14 km over McMurdo Station, Antarctica

Ozone and aerosol profiles over McMurdo Station, Antarctica (78°S), have been measured August–October for the years 1986–1995. This spans the development and decay of the recent perturbation to stratospheric aerosol caused by Pinatubo. Volcanic aerosol surface areas, in the 11–14 km region, peaked near 100 µm² cm −3 in 1991, decaying to 20–30 µm² cm −3 in 1992, 15–25 µm² cm −3 in 1993, and to background levels of 4–8 µm² cm −3 in 1994. Based on these measurements the volcanic aerosol signal persisted over Antarctica for three austral springs, implying an exponential decay rate of about 14 months. The aerosol below 14 km was correlated with previously unobserved ozone loss at these altitudes. Ozone loss rates of 5–15 ppb dy −1 (0.3–0.5 DU dy −1 ) were observed in the 10–12 and 12–14 km layers. Beginning in 1994, when the aerosol approached its pre‐Pinatubo level, ozone loss diminished in the 12–14 km layer, and was not observed in the 10–12 km layer.