Dayside auroral dynamics observed by the AGO network in Antarctica

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Auroral dynamics m the day side cusp/cleft and polar cap region have been studied using all-sky imaging data acquired at four Automatic Geophysical Observatories (AGOs) located at 70°-80° magnetic latitude in Antarctica during the period from April 5 to July 31, 1995. Poleward moving transient auroral forms with velocities of -0.5 km/s and durations of -10 min were frequently observed at the two AGO stations, PI and P4, located at 80° magnetic latitude. The transient auroral forms moved poleward and westward in the pre-noon sector, while poleward and eastward in the post-noon sector. The luminosity of the auroral 630.0 nm emissions was found to be much higher than that of the auroral 427.8 nm emissions, implying that the energies of precipitating electrons exciting these auroral transients are very low. The WIND interplanetary magnetic field (IMF) data showed that these pole- ward moving transient auroral forms were strongly correlated with northward IMF (Bz > 0) conditions. Since distinct back-scattered echoes of the HF radar at Halley Bay station were not observed when these transient aurora forms occurred, it is concluded that these auroras did not excite strong irregularities in the F-region. Thus, all these results taken together imply that these transient auroral forms are strongly related to the magnetopause boundary processes during northward IMF conditions.
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