Electron and wave characteristics observed by the THEMIS satellites near the magnetic equator during a pulsating aurora

Based on conjugate ground and THEMIS satellite observations, we show electron spectra and wave characteristics near the magnetic equatorial plane during a pulsating aurora event on the high latitude side of the auroral oval. The pulsating aurora was observed by a 30‐Hz sampled all‐sky imager (ASI) at Gillam (56.4°N, 265.4°E), Canada, at ∼0840‐0910 UT on 8 January 2008. The auroral intensity pulsation at the possible THEMIS D (THD) footprints had frequency peaks at ∼0.1–0.2 Hz. The footprint of THD was in the poleward part of the proton aurora observed by a meridian‐scanning photometer. After auroral pulsation began at ∼0842 UT, both THD and THEMIS E which was near THD in the mid‐tail at 11.6–11.8 R E , observed enhanced field‐aligned electron fluxes at energies of 1–10 keV. However, the amplitudes of whistler mode waves and electrostatic cyclotron harmonics (ECH) waves observed by THD with the highest sampling rate of 8 kHz were not significant, showing a marked contrast to the recent report of clear correlation between whistler mode waves and auroral pulsations observed at 5–9 R E . We suggest that the observed field‐aligned electrons, which are probably caused by Fermi‐type acceleration associated with earthward plasma flow in the mid‐tail plasma sheet, are modulated by some wave processes to cause pulsating auroras. Key Points A ground‐satellite conjugate observation of pulsating aurora at 12 Re Whistler‐mode and ECH wave amplitudes were weak Modulation of field‐aligned electrons by some processes