A STUDY OF MAGNETIC FIELD (Bz) AND IONOSPHERIC VARIATION DURING MAGNETIC ACTIVITIES AT LOW LATITUDE

Abstract

A large foF2 data base was collected for the four magnetic storms occurring in January 10, 1976; April 12-13, 1981; October 29, 1973 and July 8, 1975; for the low latitude station of Manila (14.70 N) in the East Asian sector. Also, plots of D(foF2) deviations versus time (UT) and that of the interplanetary magnetic field component (Bz) versus time (UT) for the low latitude station were analyzed. From our analysis, it was observed that there is a direct variation between Bz and the F2 region response. Davis et al (1997) have shown that a southward turning with change in Bz of δBz > 11.5nT results in foF2 showing a marked decrease in amplitude reaching a minimum value of 20hrs after the southward turning. It was also observed that there is homogeneity in the response of F2 region at low latitude stations (i.e. foF2 enhancement) irrespective of the period of storm event, but more pronounce during intense storms which was in agreement with Adeniyi, 1986; Mikhailov et al, 1994; who states that the positive phase in most cases (90%) is observed at equatorial latitudes during magnetic disturbances.