Hydroxyl (OH) is an atmospheric free radical of importance in the study of the photochemistry of stratospheric ozone and in the understanding of the roles of anthropogenic nitrogen and chlorine compounds which catalytically destroy ozone. The stratospheric ozone layer shields the earth's lifeforms from the damaging effects of solar ultraviolet radiation, and accurate predictions regarding its integrity require detailed knowledge of relevant photochemical processes. Measurements of OH and an understanding of its behavior are essential components of this body of knowledge. Ongoing vertical column abundance measurements at Fritz Peak Observatory, Colorado, and the Department of Scientific and Industrial Research Atmospheric Station in Lauder, New Zealand, will be continued through mid-1995 under this proposal. These are high resolution spectroscopic measurements of the absorption of sunlight by the OH molecule. The proposed work will be a continuation of the 15 year observation series in Colorado and of the 3 year series in New Zealand. Analytical studies and atmospheric model comparisons will continue in an effort to understand the mechanisms responsible for the observed behaviors of this extensive database.
