Electric field modulation behind pulsating aurora

We present, for the first time, the modulation of the electric field at ionospheric altitudes possibly associated with an occurrence of pulsating aurora. In November 2005, campaign‐based simultaneous measurements of pulsating aurora were conducted in Iceland with an all‐sky TV camera (ATV) at Tjornes (66.20°N, 17.12°W) and the SuperDARN radar at Thykkvibaer (63.77°N, 20.54°W). During an interval within the campaign period, pulsating aurora whose frequency was approximately 8 seconds were observed with the ATV in the morning sector. A quasi‐periodic oscillation was identified in the line‐of‐sight Doppler velocity from the radar backscatter colocated with the pulsating aurora. The amplitude of the velocity fluctuation ranged from 50 to 100 m s−1, which corresponds to an electric field modulation of 4–7 mV m−1. The period of the electric field fluctuation was the same as that of the optical pulsating aurora. We suggest that the oscillating Doppler velocity is driven by polarization electric fields generated through charge accumulation at the edges of region of enhanced electron density caused by the occurrence of pulsating aurora.