Abstract We present a model of stratospheric aerosol optical properties (refractive index and relative size distribution) and their variability. The model's purposes are 1) providing flexible, efficient means for converting between different aerosol macroproperties (e.g., number or mass concentration, extinction or backscatter coefficient), and 2) quantifying the uncertainties in the conversion process. The latter purpose is achieved by including the results of a sensitivity analysis in the model output products. The model has three layers, the boundaries of which are defined by tropopause height. Each layer includes a set of empirically based refractive indices and relative size distribution types. In contrast to previous models, this model allows for a range of sulfuric acid and ammonium sulfate refractive indices within the “inner stratospheric” layer (∼2 to 20 km above the tropopause, where the major peak in aerosol mixing ratio occurs). We show that nine different analytical types of size distributio...