When I was invited to write this review, I was asked to differentiate between fundamental (basic) research, applied (directed or mission-oriented) research, and implementation. The last category is described as ``that which involves commercial use and operational application of the results of the scientific investigation''. For the field of stratospheric chemistry, this is a somewhat difficult distinction to draw because the work is very applied. Some might even argue that the studies have driven commercial response more than they have provided commercial benefits. Therefore, in the context of the companion reviews, it is safe to lump stratospheric chemistry nearly entirely into the second category. However, it is possible to draw some distinctions.
Laboratory work, such as the characterization of photodissociation processes, reaction kinetics, and surface chemistry, form the basic foundation for models and measurements. Many of these studies are of fundamental physical chemical interest, regardless of their importance for the atmosphere. Most field work, on the other hand, can be considered applied, in large part because it is often mission-oriented as well as because it can be very costly and must therefore be justifiably important to taxpayers. However, field work does remain a prime motivation for laboratory studies. Assessment modeling studies represent the implementation, or operational, application of the results, as they are the primary source for predictions upon which international agreements are based. Such studies provide an important interface between stratospheric scientists and policymakers, but they are not typically used to answer specific photochemical or dynamical questions. Other theoretical studies impact our understanding of the fundamental behavior of the atmosphere by pointing out inadequacies in present understanding or by discovering potentially important new processes.
Stratospheric chemistry also represents an excellent modern example of how science can impact industry. With respect to chlorofluorocarbons, halons, and, likely, methyl bromide, the science has contributed to international agreements to phase out their use and replace them with compounds that will have a much smaller impact on stratospheric ozone. Because these chemicals are produced by large companies, the political and economic impact has been significant, and the issues have always been received considerable publicity. More recently, the stratospheric chemistry community has participated in a NASA-sponsored study of the potential impact of a new fleet of supersonic aircraft, high-speed civil transports. Results from this study are intended to provide policy-makers and airplane designers with an evaluation of the potential impact of the operation of such transports on ozone. Finally, ground-based studies can also be considered implementational, as the results of these continuous studies often drive more specific mission-oriented research carried out by satellites, balloons, and aircraft.
I thank all of my colleagues who sent information regarding their research over the past four years, helpful suggestions from anonymous reviewers, and Linnea Avallone for assisting with references and typesetting.
