Conjugate in situ observations of the stratospheric aerosol following the 1991 Mount Pinatubo eruption were made over Laramie, Wyoming (41¿N), and Lauder, New Zealand (45¿S), using balloon-borne backscattersondes. The results show similar aerosol loading and decay rates occurring over both midlatitude locations. A comparison with the 1982 El Chichon eruption as observed over Laramie indicates only somewhat higher mass mixing ratios for the Pinatubo eruption and very similar decay rates. As in the past, a strong correlation between local tropopause pressure and stratospheric aerosol mass loading was observed at the stations involved. Such a feature would be potentially useful for putting local measurements into a global prospective. ¿ American Geophysical Union 1994