Aircraft measurements of very short-lived halocarbons over the tropical Atlantic Ocean



[1] Atmospheric mixing ratios of C2H5I, CH2ClI, CH2Br2, and CHBr3 were quantified from whole air samples collected aboard the FAAM BAe 146-301 atmospheric research aircraft during flights over the tropical Atlantic Ocean (30°N to 10°S) as part of the Trade Wind Ozone Photochemistry Experiment (TROMPEX) in September 2009. Mixing ratios of C2H5I and CH2ClI increased with decreasing latitude, and concentrations of all measured halocarbons were elevated with increasing proximity to the oceanic upwelling along the coast of Mauritania. Vertical profiles highlighted the rapid photolytic degradation of these compounds within the tropical troposphere, with CH2ClI concentrations reduced by 50% at the top of the boundary layer. The spatial distributions of CH2ClI indicated an open ocean source.