Stratospheric aerosol properties and their effects on infrared radiation

This paper presents a stratospheric aerosol model and infers its effects on terrestrial radiation. Composition of the aerosol is assumed to be concentrated sulfuric acid. An appropriate size distribution has been determined from available size distribution measurements of other investigators. Aerosols composed of concentrated sulfuric acid emit energy in the atmospheric window region of the infrared spectrum, 8–13 μm. Laboratory measurements of optical constant data obtained at room temperature are presented for 75 and 90% aqueous sulfuric acid. Calculations of an aerosol extinction coefficient βext(λ) in km−1 are then performed by using the above data. Peaks in βext(λ) occur at 11.0, 10.3, and 9.6 μm for sulfuric acid aerosol composed mainly of Aitken size particles. Effects of changes in aerosol phase and temperature are discussed but not resolved.