Aerosol optical thicknesses calculated from solar spectral extinction measurements made with a sunphotometer on board a NASA Convair 990 aircraft in May, 1983 are presented. The measurements were obtained over the latitude range 71 ¿N to 56 ¿S. The latitudinal distribution of the optical thickness at 500 nm wavelength shows distinct minima of .01-.02 at 25¿ latitude in both the hemispheres, a broad maximum of about 0.12 between 50 ¿N and 60 ¿N latitude and a maximum of about 0.1 around 10 ¿S and 40 ¿S latitude. The wavelength dependence of aerosol optical thickness is nearly neutral. The median radius of aerosol particles is estimated to be between 0.16&mgr; and 0.18&mgr; at latitudes between 12 ¿S and 71 ¿N, with the maximum of 0.18&mgr; observed between the equator and 25 ¿N latitude. A median radius in the range from 0.11&mgr; and 0.15&mgr; is found at latitudes south of 12 ¿S. An aerosol mass density of .04-.05 g/m2 was estimated at latitudes between 50 ¿N and 60 ¿N and of .02-.03 g/m2 at other latitudes in the northern hemisphere. In the southern hemisphere it was .02-.03 g/m2 between 35 ¿S and 40 ¿S and .01-.02 g/m2 at other latitudes. Rough estimates of aerosol mass indicate that about 1.5 megatonnes of aerosol still persisted in the stratosphere between the equator and 25 ¿N one year after an eruption.