Letter to the Editor Geomagnetic storm eects at low latitudes
نویسنده
چکیده
The geomagnetic horizontal (H) ®eld from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed signi®cant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current eects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the eect of a westward electric ®eld due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.
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