A two-dimensional model of ion composition in the stratosphere 2. Negative ions

Abstract

A two-dimensional meridional model of negative ions in the stratosphere is presented. It indicates that NO₃ - and HSO₄ - core ions with HNO₃ and H₂SO₄ ligands are the most abundant negative ions in this region of the atmosphere. In accordance with observations at 44° N the model predicts a sharp changeover of HSO₄ - core ions over NO₃ - core ions at about 32 km. It also predicts a reverse changeover at 42 km above which NO₃ - core ions again become dominant. For other latitudes no comparison can be made due to the lack of observational data. The negative ion composition appears to be determined by sulfuric acid vapor and nitric acid concentrations. The sensitivity of the ion composition model to the concentration of these acids is discussed. Finally, the meridional distributions of major negative ions are presented. A companion paper on positive ions is presented by Beig et al. (this issue).