STRATOSPHERIC SO3 - UPPER LIMITS INFERRED FROM ION COMPOSITION MEASUREMENTS - IMPLICATIONS FOR H2SO4 AND AEROSOL FORMATION

Upper limits for the concentration of stratospheric gas phase SO3 have been inferred from a reanalysis of previous balloon-borne ion composi tion measurements made at altitudes between 29 and 41 km. Assuming ste ady state conditions for the production and loss of gaseous SO3 lower limits for the first-order loss rate coefficient of SO3 could be deduc ed. These lower limits are compared with calculated loss rate coeffici ents associated with potential loss processes for SO3 and implications for the formation of gaseous H2SO4 are discussed. In particular, the present analysis shows that no gas phase H2SO4 can be produced from th e gas phase reaction of SO3 with H2O at altitudes above the stratosphe ric H2SO4/H2O aerosol layer.