QUASI-BIDAILY VARIATION OF THE GEOMAGNETIC-FIELD IN THE INDIAN EQUATORIAL ZONE

Quasi-bidaily Variation (BDV) in the geomagnetic field due to equatorial electrojet and planetary Sq currents is clearly detected in the Indian equatorial zone. The quasi-stationary signal is stronger in EEJ compared, to SQ. Larger amplitude of the BDV in EEJ is confined only to late summer in the northern hemisphere indicative of its clear association with the planetary wave in the mesosphere below. A noticeable change in the BDV amplitude is seen following counter electrojet events. However, no concrete evidence is seen for the anticipated association between the movement of Sq focus caused by mesospheric winds and the BDV in EEJ or Sq.