First model of negative ion composition in the troposphere

A chemical model of negative ions in the troposhere (0–15 km) is presented. This model is an extension of the negative ion composition model in the lower stratosphere (Kawamoto and Ogawa, 1984, Planet. Space Sci. 32, 1223) with some modifications. The computed result shows that the predominant ions are NO₃^?HNO₃H₂O below 10km and NO^?₃(HNO₃)₂ above 10km, and that the fractional abundance of cluster ions having a HSO^?₄ core increases with height below 12km and decreases with height above it. The ions having CO^?₃ cores are at most 2% in fractional abundance. The other kinds of negative ions are far smaller in fractional abundance than the NO^?₃, HSO^?₄ and CO^?₃ core ions. The result is compared with the two mass spectrometric observed results (Heitmann and Arnold, 1983, Nature, Lond. 306, 747; Perkins and Eisele, 1984, J. geophys. Res. 89, 9649). The problems on the tropospheric negative ions which arose are discussed.