Observations over Australia of plumes from distant biomass-burning sources using remote sensing and airborne techniques

Although the free troposphere in the Southern Hemisphere has often been considered to contain very low concentrations of aerosols, significant enhancements in the aerosol loading have been reported on several occasions during the last three decades. This paper reports on the results of two recent experiments in which significant increases in the loading of aerosols and trace gases were observed over southern Australia. The Mildura Aerosol Tropospheric Experiment (MATE 98) and an experiment conducted during SAFARI 2000 used a ground-based lidar and a combination of instruments mounted on balloons and aircraft to measure increased concentrations of aerosols and trace gases. Back-trajectory analyses show that these plumes did not originate from the Australian continent, but are likely to have come from southern Africa or South America.