Nigerian Journal of Physics

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Analysis Of Interplanetary Phenomenon, Geomagnetic And Ionospheric Response Associated With The Storm Of July 8, 1975, In The East Asian Sector

V U Chukwuma, H A Lawal


A study is made of the moderate geomagnetic storm of July 8, 1975 (Dstmin =-60 nT) and its associated ionospheric storm using solar wind parameters and foF2 data obtained from ionosonde stations in East Asian longitudinal sector. The storm was found to be a double step storm with the first Dstmin resulting mainly from ring current injection due to increase in solar wind density while magnetospheric convection electric field played the leading role in the development of the second Dstmin . The analysis of the interplanetary and foF2 data show that the appearance of positive storm before the beginning of the geomagnetic disturbance in the mid-latitudes and the occurrence of strong negative phase at the low latitude station of Manila is due to the penetration of interplanetary electric field. Furthermore, available results presented ionospheric response features that bear similarity in form and magnitude with those that are due to intense storms. This suggests that a moderate storm is capable of generating ionospheric storms which are of comparable magnitude with those resulting from intense geomagnetic storms.

Keywords: Geomagnetic storm, solar wind, plasma sheet density, ring current, ionospheric storm.

Nigerian Journal of Physics Vol. 19 (1) 2007: pp. 63-74
AJOL African Journals Online