Estimation of Precipitating Electron Energy of Pulsating Aurora Using
Ground-based Multiwavelength Optical Observations
Pulsating aurora (PsA) is characterized by quasi-periodic intensity
modulations with a period of a few to a few tens of seconds. It is
caused by precipitation of energetic electrons of a few to several tens
of kilo electronvolts produced by chorus waves in the magnetosphere.
Precipitating electron energies of PsA have been identified in the past
by sounding rocket and satellite observations, but the spatial
distributions of precipitating electron energies of PsA have never been
estimated. In this study, using the data from ground-based all-sky
cameras at two wavelengths of 427.8 nm and 844.6 nm, we estimated the
temporal and spatial variations in the precipitating electron energy of
PsA. The results showed that the spatial distribution of precipitating
electron energies was not uniform in the PsA patch, suggesting that the
coherent spatial scale of the wave-particle interactions is smaller than
each PsA patch size.