Atmospheric Ozone as a Climate Gas: Studies Concerning Aircraft Emissions

Abstract

It is recognized that atmospheric O-3 distribution can be perturbed byanthropogenic activity through increased O-3 precursors (NOx, CO andhydrocarbons) in the troposphere and O-3-depleting compounds in thestratosphere (WMO, 1999). Changes in the O-3 vertical distribution,especially in the lower stratosphere and upper troposphere, can perturbthe radiative forcing of the troposphere-surface climate system withsubsequent climate implications (Wang and Sze, 1980; Lacis et al.,1990). Aircraft flying at cruising altitudes of 8 to 18 km emitpollutants of CO2, NOx, water vapor, soot and sulfate particles whichcan affect radiative forcing directly through attenuation of solar andlongwave radiation and indirectly through perturbation to O-3 and theformation of contrails (IPCC, 1999).The lecture addresses ``atmospheric ozone as a climate gas{''} with abroader perspective, covering the greenhouse effect, the radiative andchemical processes of atmospheric O-3, the concept of radiative forcingfor climate change, and then the case studies of aircraft emissionsinvolving O-3. Because changes in climate (temperature, moisture,clouds, winds) also affect the O-3 layer, the importance of interactiveclimate-chemistry in global general circulation model is also discussed.