Development of a global stratospheric aerosol climatology: Optical properties and applications for UV

A long-term stratospheric aerosol climatology is constructed using SAGE II spectral extinction measurements, worldwide lidar observations, and time se ries of atmospheric turbidity and transmission data. The results contain im portant information for assessing stratospheric aerosol effects on ultravio let (UV) radiation and are intended to provide more accurate stratospheric aerosol corrections for the Umkehr-retrieved ozone profiles. The record, da ting from 1953 to 1997, is also useful for climate studies and for estimati ng errors to other remote sensing methods. A significant part of this study involves examination of the relationships between aerosol size distributio n and optical properties as a function of wavelength. These relationships p rovide empirical means for estimating aerosol extinction at various wavelen gths, including UV-B wavelengths, from a single lidar backscatter value or from an extinction value at a different wavelength. A total of 134 size dis tributions, reported in the literature by several investigators, were used in this analysis. The results suggest the existence of a bounded and predic table domain for aerosol optical properties and indicate distinct differenc es between volcanic and background aerosol regimes. This paper summarizes t he data and methods used in the development of a stratospheric aerosol clim atology and illustrates the resulting long-term time series of monthly and zonally averaged stratospheric aerosol optical depth at 0.320 mu m. This wa velength was selected because it is close to the midpoint of the Umkehr C-p air wavelengths of 0.311 and 0.332 mu m.