OZONESONDE MEASUREMENTS AT HILO, HAWAII FOLLOWING THE ERUPTION OF PINATUBO

Ozonesonde measurements at Hilo, Hawaii (20-degrees-N), after the erup tion of Pinatubo in June 1991, are compared to measurements made there from 1985 to 1990 in order to investigate possible volcanic effects. The general nature of the ozone anomalies in 1991-92 can be summarized as lower than normal ozone below about 25 km and higher than normal o zone above. The net result was that total ozone was somewhat lower tha n average and, during late 1992, was as low as recorded in 1982, follo wing the eruption of El Chichon. Elevated temperatures in the region o f the volcanic aerosol layer and upward motion of the aerosol layer we re observed at Hilo following the eruption. Although the nature of the perturbed ozone profile may be the result of enhanced upward motion a ssociated with volcanic aerosol particle heating, and the coupling of quasi-biennial oscillation effects, the persistent nature of the pertu rbation, still present more than a year after the eruption, is not eas ily explained.