Interplanetary phenomenon, geomagnetic and ionospheric response associated with the storm of October 20-21, 1989
Recent results of the study of March 13-14, 1989, geomagnetic (Dst=-600nT) show that the depletion of foF2 was simultaneously worldwide and extended to very low latitudes. These results appear to indicate that during intense storms there are no distinct local time variations of ionospheric storm effects. Presently, the F2 region global structure response to another intense storm was studies as to confirm the earlier results. The investigation used measured parameters of solar wind plasma and imbedded IMF, and foF2 data obtained from a global network ionosondes. The results obtained from the analysis of the measured parameters of solar wind plasma, Dst and Ap data show that arrival of the shock in the interplanetary medium is indicated by increases in plasma density and velocity , and a large southward turning of Bz. In addition, Ap peak accompanies the beginning of a high-speed stream. The event of October 20-21, 1989, is a triple step storm. The analysis of the foF2 data shows that during the October 20-21 storm the depletion of foF2 was restricted to the high and middle latitudes. Although the depletion diminished in amplitude towards the lower latitude, the F2 region global structure response lacked simultaneity unlike the storm of March 13-14 in which the depletion of foF2 was extended to a latitude as low as 12.4N, and at the same time globally. The present results appear to confirm the suggestion of Chukwuma (2003) that the F2 region global structure response during the storm of March 13-14 may be due to the very intensive nature of that particular storm.
Bibliogr. 31 poz.