RESULTS OF CONDUCTIVITY, ION MOBILITY AND ION CONCENTRATION MEASUREMENTS OBTAINED WITH A PARACHUTED GERDIEN ASPIRATION ANALYZER PROBE IN HEIGHTS BELOW 70 KM

The results of conductivity, ion mobility and ion conductivity measurements performed below 70 km with a parachuted Gerdien aspiration analyser during winter and in the summer season are described. The mobility of the most abundant species of positive ions was found to be the same for summer and winter conditions. Observed increases of conductivity are therefore caused by increased carrier density. Increases of negative conductivity in heights above 40 km found in the winter seasons were probably caused by an increase of the number density of free electrons. A straight-forward relation between the number density of charged carriers and the air temperature was not found. Suggestions are made for the cause of the observed seasonal variation in ion density and in λ, the ratio of negative ions to electrons. © 1979.