Long term changes in the electrical conductivty of the stratosphere

Stratospheric electrical conductivity measurements have been made from high altitude research balloons at various locations around the world for more than 30 years. In the stratosphere, conductivity changes may indicate changes in aerosol or water vapor content. In this paper, we will compare data taken in the last five years at mid latitude locations with data taken in the previous three decades at both mid and high latitude. So far, it appears that short term variations owing to Forbush decreases, geomagnetic storms, aerosol injections by volcanos and forest fires, etc. completely obscure any long term climatic trend.