9:00 AM - 10:30 AM
[PEM13-P23] Possible roles of magnetospheric density ducts in controlling the shape of pulsating aurora and the energy of precipitating electrons
Keywords:Arase, EISCAT radar, Pulsating aurora, Chorus waves, Ducts
To reveal this issue, we have investigated a PsA event on January 12, 2021, during which simultaneous observations with the Arase satellite, ground-based all-sky imagers and the European Incoherent SCATter (EISCAT) radar were conducted. Through the analysis of the simultaneous measurements, we have tried to clarify the relationship between the morphology of PsA and the energy of PsA electrons, and then to understand what factors control the relationship. One of the main results is that, when the shape of PsA was patchy, the energy of the corresponding PsA electrons exceeded tens keV. In addition, during this interval of relatively harder precipitation, chorus wave was observed by Arase at MLAT higher than 20°. Furthermore, 1) the energy flux of scattered electrons, 2) the filling ratio of loss cone at the satellite location, and 3) the energy flux of PsA electrons estimated from EISCAT showed a reasonable correlation. On the basis of these observational results, we hypothesize that the spatial structure of PsA and the energy of PsA electrons are controlled by the existence of “density ducts,” which are tube-like regions where the electron density is lower or higher than the surrounding area. Those structures guide chorus waves along the magnetic field, allowing them to propagate to higher MLAT. In order to test this hypothesis, we compared the irregularity of the background electron density measured by Arase in the magnetosphere with the emission intensity of PsA patches at the footprint. The irregularity of ~2—18% in the electron density possibly due to the existence of ducts and the emission intensity of PsA patches show a good spatiotemporal correspondence, which supports the above-mentioned hypothesis. In the presentation, we show the observational results and discuss the factors controlling the morphology of PsA and the energy of PsA electrons.