Possibility of predicting the negative phase of certain ionospheric storms

Six winter and five summer ionospheric storms over 1979-1982 are analyzed. The relationship between positive (delta f0F2 greater than 0) and negative (delta f0F2 less than 0) phases of storms for Leningrad and Moscow are examined in terms of the mean intensity of each phase and their S parameter, characterizing the area beneath the delta f0F2 curve for each phase. It is shown that the derived S-parameter relationships can be used to predict the character of the development of a negative phase according to the parameters of an observed positive phase.