Electromagnetic induction due to SSC at equatorial electrojet stations

Abstract

The effects of storm sudden commencements (SSC) in the horizontal (<i>H</i>)<i>, </i>vertical (<i>Z</i>) and eastward (<i>Y</i>) geomagnetic fields at the five equatorial electrojet stations operating during IGY-IGC period have been discussed. The amplitude of SSC (<i>H</i>) at any of the stations was maximum around midday hours. The amplitude of SSC (<i>Z</i>) showed an abnormally large positive value at Trivandrum, the ratio Δ<i>Z</i>/Δ<i> H </i>exceeding 1.0 at any time of the day or night. These phenomena are discussed in terms of the currents in the ionosphere/magnetosphere and their induced effects in subsurface conducting layers. The most promising source for large SSC effects in <i>Z</i> at Trivandrum seems to be due to the concentration of normal induced currents over a wide latitude zone north and south of the magnetic equator through the conducting graben in the Palk Strait, besides the channelling of induced ocean currents in the Bay of Bengal and Indian Ocean physically through the Palk Strait between

India and Sri Lanka.