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To investigate the dynamics of auroras and faint upper atmospheric emissions, a new type of imaging instrument was developed. The instrument is a wide field of view, narrow-spectral-band imaging system using an intensified S.E.C. TV camera in a time exposure mode. Pictures were taken at very low light levels of a few photons per exposure per resolution(More)
[1] The ISUAL experiment on the FORMOSAT-2 satellite has confirmed the existence of ionization and Lyman-Birge-Hopfield (LBH) band emissions in elves. In this paper, an in-depth study of the ISUAL recorded elves was carried out. Numerical simulation results of elves based on an electromagnetic finite difference time domain (FDTD) model of the emissions(More)
Dayside merging between the interplanetary and terrestrial magnetic fields couples the solar wind electric field to the Earth's magnetosphere, increases the magnetospheric convection and results in efficient transport of solar wind energy into the magnetosphere. Subsequent reconnection of the lobe magnetic field in the magnetotail transports energy into the(More)
The structure of Earth's magnetosphere is poorly understood when the interplanetary magnetic field is northward. Under this condition, uncharacteristically energetic plasma is observed in the magnetotail lobes, which is not expected in the textbook model of the magnetosphere. Using satellite observations, we show that these lobe plasma signatures occur on(More)
In a conventional grating spectrograph consisting of a single entrance slit, a grating, and a multichannel (imaging) detector, considerable light throughput advantage can be realized by replacement of the single entrance slit with a mask. This replacement can yield a signal-to-noise ratio increase because of increased light collection over an extended area(More)
The most important process that allows solar-wind plasma to cross the magnetopause and enter Earth's magnetosphere is the merging between solar-wind and terrestrial magnetic fields of opposite sense-magnetic reconnection. It is at present not known whether reconnection can happen in a continuous fashion or whether it is always intermittent. Solar flares and(More)
[1] In this study, we compare sprite streamer modeling results with Imager of Sprites and Upper Atmospheric Lightning (ISUAL) spectrophotometric data for several sprite events. The model positive streamers are simulated for two representative magnitudes of the quasi-electrostatic field produced by cloud-to-ground lightning discharges, reflecting conditions(More)
[1] Three intensity ratios of the second positive band system of N 2 to N 2 LBH band system, the first negative band system of N 2 + , and the first positive band system of N 2 are obtained separately from sprite streamer modeling and from measurements by ISUAL instrument on FORMOSAT-2 satellite. The direct comparison between the obtained ratios indicates(More)
The IMAGE spacecraft uses photon and neutral atom imaging and radio sounding techniques to provide global images of Earth's inner magnetosphere and upper atmosphere. Auroral imaging at ultraviolet wavelengths shows that the proton aurora is displaced equatorward with respect to the electron aurora and that discrete auroral forms at higher latitudes are(More)
Magnetospheric substorms explosively release solar wind energy previously stored in Earth's magnetotail, encompassing the entire magnetosphere and producing spectacular auroral displays. It has been unclear whether a substorm is triggered by a disruption of the electrical current flowing across the near-Earth magnetotail, at approximately 10 R(E) (R(E):(More)