Airborne lidar measurements of ozone and aerosols over the Amazon rain forest

Abstract

The NASA airborne differential absorption lidar (DIAL) system has been used to investigate O3 and aerosol distributions in numerous Global Tropospheric Experiments (GTE) over the past 3 years. This paper discusses the measurements of O3 and aerosols during the GTE Amazon Boundary Layer Experiment (GTE/ABLE-2A) conducted from Manaus, Brazil, in July–August 1985. During the GTE/ABLE-2A field experiment, the airborne DIAL system was used to investigate the structure and dynamics of the planetary boundary layer (PBL) and the free troposphere during undisturbed and disturbed atmospheric conditions. Undisturbed day-time O3 mixing ratios were found to be ~17 ppbv in the mixed layer and 25–30 ppbv in the previous day’s PBL. Regions of high and low O3 mixing ratios were seen in outflow regions of deep convective storms due to downward and upward transport processes, respectively. Large-scale variations in the vertical and horizontal distributions of O3 and aerosols were observed on all flights with O3 exceeding 50 ppbv in localized regions of haze, which has been related to biomass burning. A significant increase in O3 and aerosol concentrations across the Amazon Basin was observed over the period of ABLE-2A. The airborne DIAL results for GTE/ABLE-2A are presented in this paper, and they are discussed in relation to the chemistry and dynamics of the atmosphere over the tropical rain forest of Brazil.