BOX AND GAUSSIAN PLUME MODELS OF THE EXHAUST COMPOSITION EVOLUTION OFSUBSONIC TRANSPORT AIRCRAFT IN AND OUT OF THE FLIGHT CORRIDOR

A box and a Gaussian plume model including gas-phase photochemistry an d with plume dispersion parameters estimated from the few available pl ume observations are proposed and used for evaluation of photochemical transformations of exhausts from a single subsonic transport aircraft . The effects of concentration inhomogeneities in the plume cross sect ion on the photochemical sources and sinks in the plume are analyzed f or various groups of compounds. The influence of these inhomogeneities on the rate and on the mass of ambient air entrainment into the plume are studied also by comparing the box and the Gaussian plume model si mulations during the first hours of their ''life''. Due to the enteran ce of HOx and NOx from ambient air into the plume with rates varying f rom the wind shear and turbulence conditions, the rate of emitted NOx oxidation in the plume is dependent on these and also on the backgroun d concentration levels of HOx and NOx.