Sulfur dioxide measurements in the tropical troposphere: Deployment of an aircraft-based CIMS instrument with permanent in-flight calibration during the SCOUT-O3 tropical campaign.

Abstract

During the SCOUT-O3 tropical campaign which took place around Darwin (Australia) in November/December 2005 sulfur dioxide measurements were performed using an aircraft-based chemical ionization mass spectrometer (CIMS) with permanent in-flight calibration. A total of 17 tropical flights were carried out. The SO2 mole fractions were spatially highly variable, with high values in the boundary layer (up to 10 ppbv) but also distinct signatures in the free troposphere (10-300 pptv) and importantly even in the upper troposphere. Here we present an overview over the data with focus on some particularly interesting flights.