Driver of Pulsating Aurora Revealed Pulsating aurora PA

Driver of Pulsating Aurora Revealed Pulsating aurora (PA), a spectacular emission that appears as blinking of upper atmospheric optical emissions in the polar region, is known to be excited by modulated, downwardstreaming electrons. In spite of its distinctive features, the identification of the driver of the electron precipitation has been a long-standing problem. Using coordinated satellite and ground-based all-sky imager observations from the THEMIS mission, we provide direct evidence that a naturally-occurring electromagnetic wave, lower band chorus, can drive pulsating aurora. Almost one-to-one correlation between chorus amplitude observed on THEMIS and PA luminosity in the ionosphere was obtained over only a single auroral patch and the correlation outside this area diminishes quickly with increasing distance, demonstrating a clear link between the two phenomena. The PA observations provide a unique opportunity to identify the footprint of the magnetic field line threading a given spacecraft to a precision within an auroral patch size (<~100 km) and possibly even down to a few pixels (~10 km).

Auroral imager snapshots at the times marked in the figure below (a-d). The auroral patch indicated by the red arrow (Panel b and d) occurred simultaneous with chorus intensifications. b ac d