Effect of Ionic Processes on Neutral Constituents

Reactions between ions and neutral species, can, in principle, affect the budgets of neutral species as mentioned in Chapter 5. 

In the stratosphere, the present understanding of the ion composition and chemistry is not adequate to completely describe the possible interactions. The ion production by cosmic rays appears, however, to be too small to modify the neutral composition substantially, except near the tropopause, where the ionization and decomposition of N2 leads to a small production of nitrogen oxides (Warneck, 1972 Nicolet and Peetermans, 1972 Brasseur and Nicolet, 1973). 

During intense solar proton events, the number of ion pairs produced can increase greatly even at relatively low altitudes, perturbing the neutral atmosphere and leading to a considerable increase in the rate of production of nitrogen and hydrogen oxides (see e.g., Swider and Keneshea, 1973 Crutzen et al, 1975 Jackman et al, 1980 1990 1995 Reid et al., 1991). 

In principle, ions can provide a loss mechanism for species formed at ground level which are long lived in the lower atmosphere. For example, 

In the stratosphere, positive ions could contribute to the conversion of nitrogen oxides into nitric acid by the following chain  

---