ON THE ATMOSPHERIC IMPACT OF LAUNCHING THE ARIANE-5 ROCKET

Calculations have been performed in a two-dimensional chemical-radiati ve-transport model of the atmosphere aimed at investigating the atmosp heric response to launching the Ariane 5 rocket. Various pollutants em itted from the rocket were studied: inorganic chlorine, water vapour, and aluminium oxide. The calculations also considered whether the atmo spheric response differs according to the form in which inorganic chlo rine is released. Both long-term global and short-term local responses were investigated. After 20-model years of inorganic chlorine and wat er vapour emissions, with 10 launches per year, only small losses of o zone, of the order of less than 0.1%, were calculated. These losses we re independent of the form of inorganic chlorine. Recovery of the atmo sphere after the cessation of launches was rapid, and all but complete within 5 years. Local ozone loss after a single rocket launch was als o limited, but the magnitude was dependent upon the form in which chlo rine was released. The effect of releasing Al2O3 from Ariane 5 was a m odest increase in the sulphate aerosol mass mixing ratio throughout mo st of the stratosphere.