Geomagnetic and ionospheric disturbances of internal meteorological type - A synergistic approach to disturbances

Measurements of geomagnetic activity, ionospheric-disturbance factors and neutral-gas parameters made at ground stations in the GDR and France and from satellites (Intercosmos-17, Solrad-10, ATS-3) during 1956-1981 are analyzed statistically. Mean and median geomagnetic activity is found to exhibit distinct annual recurrence patterns which are correlated with fluctuations in the neutral-gas and plasma parameters. The period of frequent major ionospheric disturbances occurring regularly from October 25 through November 2 is studied in detail, and strong correlations with other parameters are found. It is proposed that these disturbances, while affected by external (mainly solar) forces, are primarily internally triggered by meteorological processes in the lower atmosphere, a finding supported by satellite data on the structural variation of thermospheric neutral gas.