Variability of H-Component of the Geomagnetic Field from Some Equatorial Electrojet Stations

The hourly variation of the H-component of the geomagnetic field from ten MAGDAS observatories along the dip- equator was used to study the variation trend of solar quiet and solar disturbed variation. The variation in H with Sq (H) enhancement in all the ten stations which peak around local noon with steady similar pattern of variation in all the EEJ, are attributed to the enhanced dynamo action at these regions. The variation of Sq (H) was in the range of 20 to 170nT with peaks around 1200-1300LT. Generally, the magnitude of variation on disturbed days are higher due to ionospheric disturbances originating from the external drives such as space weather effects, storms etc. The results also confirmed the presence of counter electrojet, occurring in the morning and evening hours with the maximum amplitude of -25nT recorded during pre-sunset. The data also show that there is a longitudinal variability in the EEJ, with results showing strongest EEJ current in the South American Sector. Pronounced equinoctials maximum which is due to enhanced electron density at equinox was recorded on March and September with the magnitude between 40 to 140nT; a range of about 100nT.