Statistical Study on Pulsating Auroras and High‐Latitude Propagation of Chorus Waves Based on Conjugate Observations of Ground‐Based Imagers and Arase Satellite

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Abstract Pulsating aurora (PsA) is one of the common diffuse auroras typically generated by ∼10 keV electron precipitation. Precipitating electrons are scattered via wave‐particle interactions with whistler‐mode chorus waves in the magnetosphere. Previous studies have observationally demonstrated that, during PsAs, highly energetic electrons with energies ranging from a few hundred keV to a few MeV simultaneously penetrate into lower altitudes and can cause ozone depletion in the mesosphere and upper stratosphere. Recent attention has focused on the importance of high‐latitude propagation of chorus waves through magnetospheric density ducts for the precipitation of such highly energetic electrons. Our previous study showed that patchy structures of PsAs reflect the cross section of ducts. However, no statistical study has examined the relationship between ducted propagation of chorus waves and PsAs using ground‐satellite conjugate observations. Thus, we perform a statistical analysis to evaluate this relationship using data from the ground‐based optical network in Scandinavia and the Arase satellite. The results show that when chorus waves propagate to higher latitudes while maintaining their electromagnetic properties, PsAs exhibit patchy structures with more than 90% probability, and occurrence increases from midnight to the morning sector. In addition, the background electron density irregularities indicative of ducts were also observed in four events during high‐latitude propagation of electromagnetic chorus waves. For these events, the equatorial projection sizes of PsA patches ranged from several hundred to several thousand kilometers, comparable to the scale required to confine chorus waves. These observations suggest the horizontal scale of ducts at the magnetic equator.

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