Aircraft-based Trace Gas Measurements in a Primary European Ship Corridor

Abstract

Aircraft measurements of gaseous ship emissions were performed in the vicinity of the heavily travelled ship lanes through the English Channel and in the exhaust trail of a major seagoing container ship. In the single ship plume experiment the concentration and dilution of major emissions (CO2, NO, NOy, SO2) were measured up to a distance to the source ship and plume age of 25 km and 1650 s, respectively. Emission factors for NOx and SO2 were determined from individual plume encounters. The inferred NOx emission indices compare well with calculated emission indices from the engine emission model of the manufacturer. The deduced SO2 emission indices from the SO2 enhancements in the plume are smaller than calculated emission indices bases on the analysed sulphur content in the fuel sample. However, the difference is still within the estimated error limits for the SO2 emissions factor measurements. A survey flight in the ship corridor through the English Channel revealed the presence of a multitude of ship plumes aged between 0.5 and several hours. Many of the observed concentration enhancements in the ship corridor are due to the super-position of several plumes with different ages.