12 research outputs found
Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points
In recent years, aurora observation networks using
high-sensitivity cameras have been developed in the polar regions. These networks allow dimmer auroras, such as pulsating auroras (PsAs), to be observed with a high signal-to-noise
ratio. We reconstructed the horizontal distribution of precipitating electrons using computed tomography with monochromatic PsA images obtained from three observation points.
The three-dimensional distribution of the volume emission
rate (VER) of the PsA was also reconstructed. The characteristic energy of the reconstructed precipitating electron flux
ranged from 6 to 23 keV, and the peak altitude of the reconstructed VER ranged from 90 to 104 km. We evaluated the
results using a model aurora and compared the model’s electron density with the observed one. The electron density was
reconstructed correctly to some extent, even after a decrease
in PsA intensity. These results suggest that the horizontal distribution of precipitating electrons associated with PsAs can
be effectively reconstructed from ground-based optical observations
Generation mechanism of low-energy electron precipitation in pulsating aurora elucidated with Arase satellite, ground-based optical and radar observations, and computed tomography
Generation mechanism of low-energy electron precipitation in pulsating aurora elucidated with Arase satellite, ground-based optical and radar observations, and computed tomography
Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points
Abstract
In recent years, aurora observation networks using high-sensitivity cameras have been developed in the polar regions. These networks allow dimmer auroras, such as pulsating auroras (PsAs), to be observed with a high signal-to-noise ratio. We reconstructed the horizontal distribution of precipitating electrons using computed tomography with monochromatic PsA images obtained from three observation points. The three-dimensional distribution of the volume emission rate (VER) of the PsA was also reconstructed. The characteristic energy of the reconstructed precipitating electron flux ranged from 6 to 23 keV, and the peak altitude of the reconstructed VER ranged from 90 to 104 km. We evaluated the results using a model aurora and compared the model’s electron density with the observed one. The electron density was reconstructed correctly to some extent, even after a decrease in PsA intensity. These results suggest that the horizontal distribution of precipitating electrons associated with PsAs can be effectively reconstructed from ground-based optical observations
Diffuse and pulsating aurora
This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-particle interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-particle interaction. Finally we discuss open questions of diffuse and pulsating aurora
Simultaneous pulsating aurora and microburst observations with ground-based fast auroral imagers and CubeSat FIREBIRD-II
Abstract
We report on the relationship between a pulsating aurora and a relativistic electron microburst using simultaneous observations of ground-based fast auroral imagers with the FIREBIRD-Ⅱ CubeSat for the first time. We conducted a detailed analysis of an event on October 8, 2018 and found that the occurrence of the pulsating aurora with internal modulations corresponds to the flux enhancement of electrons with energy ranging from ∼220 keV to >1 MeV detected with Flight Unit 4, one of FIREBIRD’s CubeSat, with a time delay of ∼585 ms. Combining of this time delay result and time of flight model, we suggest that the pulsating aurora and the microburst occur simultaneously due to the chorus waves at different latitudes along the same field-line as predicted by Miyoshi et al. (2020, https://doi.org/10.1029/2020gl090360)