Remarkable Solar Cycle and Seasonal Dependence of the Diurnal Geomagnetic D-Variations at Equatorial Electrojet Station, Kodaikanal.

Concurrent with the midday maximum of horizontal geomagnetic field, H, the eastward field Y at the equatorial electrojet station Kodaikanal shows a distinct minimum around noon during any of the years of solar cycle. The sunspot cycle variations of the daily variations of ΔY are sympathetical with those of ΔH. Even the day to day fluctuations of the daily range Y are correlated with corresponding changes of H. Abnormal seasonal changes are seen in the daily variations of Y field at Kodaikanal as well as at other. observations in India. These significant daily variations of eastward field at Kodaikanal are suggested to be due to a systematic meridional current associated with the electrojet current.