Interest in the global tropospheric chemistry of organic materials has been growing rapidly over the past decade. In addition to a basic concern about the fundamental biogeochemical cycles of organic matter, this interest has arisen largely because of concern about the oxidant‐forming potential of natural hydrocarbons, the possible importance of nonmethane hydrocarbons as a source for atmospheric CO, and the role played by organic material in the formation of secondary aerosol particles. In this review we consider the information presently available on concentration distribution, sources, sinks, and atmospheric transformation reactions of organic matter in the global troposphere. The data base for tropospheric organic compounds is very small. However, it is apparent that while anthropogenic sources often dominate the atmospheric chemistry of organic material in urban and near‐urban air, a key to understanding the global cycling of tropospheric organic substances is a clear understanding of the interaction of the atmosphere with the terrestrial and marine biosphere.

Estimates of the annual mass and ozone transport from the stratosphere to the troposphere are presented for the northern hemisphere. The mass transport is based on the radioactivity concentrations previously measured in tropopause folding events and the observed rate of deposition of gøSr from bomb tests. The ozone transport is deduced from the positive correlations between the ozone mixing ratio and i•otential vorticity and between potential vorticity and 'øSr radioactivity. To support these concepts, new observational data obtained from fast-responding ozone and meteorological sensors aboard the National Center for Atmospheric Research Electra aircraft and a similar ozone sensor aboard a commercial aircraft are compared to folded tropopause structures analyzed from radiosonde observations. Two tropopause folding events were predicted in advance to coordinate the flights and to traverse the predicted structures. Excellent agreement is shown between the aircraft and radiosonde data for the macroscale structures. For the first time, direct observations of the effects of mesoscale wave motions on the ozone mixing ratio, potential temperature, and wind speed perturbations are presented. The wave modes have not yet been identified, but transverse gravity waves can be eliminated from the observed polarization relations.

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