It is shown that the amplitude of storm sudden commencement (SSC) at a
station within the equatorial electrojet belt experiences daytime enh
ancement, latitudinal enhancement, and longitudinal enhancement just a
s do the similar characteristics of the strength of the equatorial ele
ctrojet current itself. lt is concluded that the sudden commencements
of geomgnetic storms are associated with an increase of electric field
s in the dynamo region modifying primarily the equatorial rather than
Sq currents. The V x Bz electric field generated at the magnetopause d
ue to the impact of the solar plasma is transmitted along the magnetic
lines of force to polar latitude as dusk to dawn electric field which
is instantaneously transmitted to the equatorial latitude as transver
se magnetic waveguide mode between conducting ionosphere and Earth. Th
e enhancements of SSC amplitude over the magnetic equator seem to be r
elated to the basic ionospheric conductivity at the longitude concerne
d.