Seasonal-and latitudinal variations of stratospheric small ion density and conductivity

Abstract

The seasonal and latitudinal variations of stratospheric small ion density and conductivity are studied using a simplified ion-aerosol model which includes the charged aerosol-ion recombination and charged aerosol-aerosol recombination, in addition to the usual ion-ion recombination and ion-aerosol attachment processes. The charged aerosol-ion recombination coefficient is computed from the model and the desirability of such a computation is discussed. The model computations in this study assume the background stratospheric aerosols (or Hake distribution), but the model is particularly useful in the study of stratospheric ion density and conductivity under conditions of enhanced stratospheric aerosols resulting from volcanic eruptions. The model results show seasonal and latitudinal variations of both small ion density <i>N</i>_± and conductivity <i>σ</i>_±. It has been shown that the latitudinal variation of <i>σ</i>_± is primarily controlled by the corresponding variation in <i>N</i>_±, whereas, the seasonal and height variations of <i>σ</i>_± are largely governed by the corresponding variations in the ion mobility <i>b</i>_±. The available experimental profiles for low, middle and high latitudes show good agreement with those from model prediction.