Ozone in the remote troposphere: mixing versus photochemistry

Ozone in the lower troposphere has traditionally been attributed to two different sources, injection from the stratosphere and local or regional photochemical synthesis. Recently, Chameides and Walker [1973, 1976] proposed that photochemical synthesis of ozone (via a methane oxidation chemistry) is significant in areas remote from obvious pollution. They characterize as their ‘basic argument that photochemical sources of ozone in the troposphere are larger than the source provided by transport from the stratosphere’ [Chameides and Walker, 1974]. This photochemical hypothesis appears welcome amid several reports of repeated but intermittent high concentrations of ozone at surface measuring stations in supposedly unpolluted areas [A ttmannspacher and Hartmannsgruber, 1973; Wallis et al., 1975] (also, data of L. A. Ripperton and J. J. B. Worth as summarized by Corn et al. [1975]).