Aircraft Measurements of Various Sulfur Compounds in a Marine and Continental Environment

Measurements of gaseous sulfur species were performed in the boundary layer and in the free troposphere around the Azores (Portugal) and over Southern Bavaria (FRG). GC/FPD-, fluorescence and chemiluminescence techniques were applied for the detection of COS, CS2, DMS, H2S and SO2. At the Azores CS2 was detectable only in the boundary layer with values between 3 and 6 pptv. SO2 decreased sharply from 300 pptv in the boundary layer to 20–100 pptv in the free troposphere wheras the concentration of COS showed only little variations. Over Bavaria SO2-values lower than 1 ppbv indicated the advection of clean airmasses. With the exception of COS the mixing ratio of the other compounds decreased considerably with height (most pronounced for DMS). In the free troposphere DMS concentrations were generally below the detection limit (0.2 pptv) while CS2 was measured in the range of 2–4 pptv and H2S below 20 pptv. Rawinsonde data and trajectories show that the vertical distribution of the sulfur compounds is influenced by meteorological conditions as well as by their sources and sinks.