Impact of recent total ozone changes on tropospheric ozone photodissociation, hydroxyl radicals, and methane trends

Trends in total atmospheric ozone from 1979–1989 were analyzed to derive the corresponding changes in the tropospheric photodissociation rate coefficient J 1 for the reaction O 3 + hv (λ < 330 nm) → O 2 + O( 1 D). Zonally and annually integrated trends in J 1 are +3.8±2.9 % per decade in the Northern hemisphere and +4.1±2.7 % per decade in the Southern hemisphere. Changes in OH due to the J 1 trends may have contributed to the slowing of atmospheric methane increases observed in recent years.