Abstract

The eruption of Mt. Pinatubo (15.1°N, 120.4°E) in the Philippines on June 15, 1991, injected large amounts of SO₂ into the stratosphere as high as 30 km (McCormick, 1992). The SO₂underwent rapid conversion to H₂SO₄/H₂O aerosol, and after the first few weeks following the eruption, the aerosol had dispersed in a band over the tropics between 20°S and 30°N. In subsequent weeks, substantial amounts of aerosol were transported to the mid-latitudes of both hemispheres, and by early September, satellite observations indicated a layer of Pinatubo aerosol centered near 21 km had reached as far south as the outer edge of the Antarctic polar vortex (McCormick and Veiga, 1992). In addition, the Cerro Hudson volcano in southern Chile (45.92°S, 73.0°W) erupted intermittently from August 12-15, 1991, sending significant amounts of SO₂ into the lower stratosphere, primarily below 14 km. Satellite observations indicated that the Cerro Hudson cloud initially became embedded in a predominantly westerly flow, and after two weeks was dispersed in a band between 50°S and 65°S (Doiron et al.,1991). Thus, at the onset of the 1991 Austral spring, two distinct volcanic aerosol clouds were present in the stratosphere over the polar regions of the Southern Hemisphere. In this study, we utilize SAM II and SAGE II data to identify and track the movement of these volcanic clouds and study transport processes associated with the Antarctic polar vortex during the spring.

© 1993 Optical Society of America