LITE and SAGE II measurements of aerosols in the southern hemisphere upper troposphere

Two global satellite data sets have been used to characterize the behavior of aerosols in the upper troposphere of the southern hemisphere during the spring season. The first data set was obtained by the Lidar-In-Space Technology Experiment (LITE) during 10 days in September 1994 and provides high-resolution information about aerosol layering and optical characteristics. The second data set was obtained by the Stratospheric Aerosol and Gas Experiment (SAGE) II over the time period 1984-1996 and provides information on the aerosol distribution and longterm climatology. During September, elevated aerosol layers are found to occur within a latitude band between 20 degrees S and 40 degrees S that extends to almost all longitudes. The latitude and altitude distribution and the optical characteristics of the aerosol suggest that a major source is smoke from biomass burning within the southern hemisphere. This conclusion is supported by the results of back-trajectory analyses that show airmasses originating in the region of southern Africa and traveling longitudinally across the Indian Ocean and Australia into the western Pacific Ocean. The dominant source of the smoke is uncertain, but quite possibly some of it may have originated from Brazil, with additions from southern Africa. The aerosol distribution shows strong similarities to published distributions for ozone and carbon monoxide, also believed to have originated from biomass burning.