Disturbed Day Variation of Geomagnetic H-Field along the Magnetic Equator

Abstract

The structure of the equatorial electrojet during disturbed condition is examined using data from 10 MAGDAS stations along the magnetic equator. Most of the variations occurred around noon. The trend of the variations when observed are not consistent, non-periodic and the variations were highly dispersed. The highest magnitude of the variations recorded is 185nT at Langkawi. Some regular magnetospheric activities connected to local solar time may be a potential source for the phenomenon. Counter eletrojet (CEJs) were recorded during this period. This is as a result of reversal of electric fields due to lunar tides, substorm and winds. Their amplitudes and time of occurrence varies respectively. CEJs occur during the morning hours and evening hours with intensities up to -75nT. The magnitudes of EEJ during the time of occurrence of CEJ events appreciably decreased. It was also observed that noontime peaks of EEJ is either delayed or advanced during CEJ events.

Keywords: Equatorial electrojet, Counter electrojet, Magnetic equator