Fine mode participate sulphur in the tropopause region measured from intercontinental flights (CARIBIC)

Here the first systematic study of the concentration of particulate sulphur in the upper troposphere and lower stratosphere is presented. The measurements were undertaken in the CARIBIC programme during intercontinental flights from a commercial aircraft, which was equipped with an aerosol inlet and a research payload in the cargo bay. Aerosol samples were collected and analysed for elemental composition. The data set comprises 21 flights between Germany and Male/Colombo in the Indian Ocean. The average fine mode, particulate sulphur concentration was 14 ng/m³ STP, which is low compared to remote areas at the Earth's surface. A pronounced dependence with latitude with elevated concentrations occurring within the densely industrialised northern hemispheric mid latitudes was observed, thus suggesting anthropogenic influence on the climate from sulphate particles in the tropopause region.