Post-noon two-minute period pulsating aurora and their relationship to the dayside convection pattern |
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| Authors: | S E Milan T K Yeoman M Lester J Moen P E Sandholt |
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| Institution: | (1) Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK;(2) UNIS, PO Box 156, N-9170 Longyearbyen, Norway;(3) Department of Physics, University of Oslo, PO Box 1048, Blindern, N-0316 Oslo, Norway |
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| Abstract: | Poleward-moving auroral forms, as observed by meridian-scanning photometers, in the vicinity of the cusp region are generally assumed to be the optical signature of flux transfer events. Another class of quasi-continuous, short period (1–2 min) wave-like auroral emission has been identified, closely co-located with the convection reversal boundary in the post-noon sector, which is similar in appearance to such cusp aurora. It is suggested that these short period wave-like auroral emissions, the optical signature of boundary plasma sheet precipitation in the region 1 field-aligned current system, are associated with ULF magnetohydrodynamic wave activity, which is observed simultaneously by ground magnetometer stations. This association with ULF wave activity is strengthened by the observation of several harmonic frequencies in the pulsation spectrum, each an overtone of the fundamental standing wave resonance frequency. |
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| Keywords: | Magnetospheric physics (auroral phenomena magnetopause cusp and boundary layers MHD waves and instabilities) |
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