Ion Drift Measured by MU Radar and Its Comparison with Geomagnetic Field Variation

By using MU radar at Shigaraki, Japan, ion drift and the electron density profile in the F region were observed during two periods, September 17-18 and October 7-8, 1986. Between 23h LT and 24h LT on September 17, a clear difference was found between the electron density profiles observed by the eastward and westward beams, which may be caused by a wave propagated from east to west. A clear negative correlation between the perpendicular northward (V⊥) and parallel (V//) component of the velocity, which is caused by the F region dynamo action, was found as observed at Arecibo. The daily variation pattern of V⊥ was similar to that observed at Arecibo, especially in the daytime, but that of the eastward drift was different. Geomagnetic field variations were estimated by using a drift velocity and conductivities deduced from the IRI 79 model (IRI 79, 1981) compared to observations at Miyazu, approximately 110km northwest of the radar site. Discordance between the estimated and observed field variations was concluded to be caused by ionospheric winds, which contribute to the generation of the geomagnetic Sq field through the induced electric field.

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