An Overview and Initial In-Orbit Status of INDEX S...

Saito, Hirobumi; Mizuno, Takahide; Tanaka, Koji; Sone, Yoshitsugu; Fukuda, Seisuke; Sakai, Shin‐ichiro; Okuizumi, Nobukatsu; Mita, Makoto; Fukushima, Yosuke; Hirahara, Masafumi; Asamura, Kazushi; Sakanoi, Takeshi; Miura, Akira; Ikenaga, Toshinori; Masumoto, Yoshinari

doi:10.2514/6.iac-05-b5.6.b.05

Cited by 7 publications

(4 citation statements)

References 4 publications

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“…The Reimei satellite, launched from the Baikonur Cosmodrome in Kazakhstan on 23August 2005, orbits the Earth at an altitude of approximately 630 km with an orbital inclination of 98.6 deg [ Saito et al , 2005]. In order to investigate the fine structure and variations of auroral phenomena, the Reimei satellite carries five scientific instruments: top‐hat‐type auroral electron and ion energy spectrum analyzers (ESA and ISA) [ Asamura et al , 2003], a three channel monochromatic auroral imaging CCD camera (MAC) [ Sakanoi et al , 2003], current probes (CRM) and magnetic field sensors (GAS).…”

Section: Instruments and Simultaneous Observationsmentioning

confidence: 99%

Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

et al. 2008

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[1] The relationship between bulk ion upflows and suprathermal ions was investigated using data simultaneously obtained from the European Incoherent Scatter (EISCAT) Svalbard radar (ESR) and the Reimei satellite. Simultaneous observations were conducted in November 2005 and August 2006, and 14 conjunction data sets have been obtained at approximately 630 km in the dayside ionosphere. Suprathermal ions with energies of a few eV were present in the dayside cusp region, and the ion velocity distribution changed from an isotropic Maxwellian near the cusp region to tail heating at energies above a few eV in the cusp region. The velocity distribution of the suprathermal ions has a peak perpendicular or oblique to the geomagnetic field, and the temperature of the suprathermal ions was 0.9-1.4 eV. An increase in the phase space density (PSD) of the suprathermal ions, measured with the Reimei, was correlated with bulk ion upflow observed at the same altitude using EISCAT, and with the energy flux of precipitating electrons with energies of 50-500 eV. The PSD also has a good correlation with the electron temperature, which was increased by precipitation, but not with the ion temperature (0.1-0.3 eV) at the same altitude measured with EISCAT. These results suggest that plasma waves such as broadband extremely low frequency (BBELF) wavefields associated with precipitation are connected to the bulk ion upflows in the cusp and effectively cause the heating of suprathermal ions. The heating of suprathermal ions disagrees with anisotropic heating due to O + ÀO resonant charge exchange.

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Section: Instruments and Simultaneous Observationsmentioning

confidence: 99%

Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

et al. 2008

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“…Reimei is the first Japanese small scientific satellite launched on August 24, 2005 [ Saito et al , 2005]. It has a sun‐synchronous polar orbit in the 0050 – 1250 local time meridian at an altitude of ∼ 640 km with an orbital period of 98 min.…”

Section: Instrumentation and Methodsmentioning

confidence: 99%

Small and meso‐scale properties of a substorm onset auroral arc

et al. 2010

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[1] We present small and meso-scale properties of a substorm onset arc observed simultaneously by the Reimei and THEMIS satellites together with ground-based observations by the THEMIS GBO system. The optical observations revealed the slow equatorward motion of the growth-phase arc and the development of a much brighter onset arc poleward of it. Both arcs showed the typical particle signature of electrostatic acceleration in an inverted-V structure together with a strong Alfvén wave acceleration signature at the poleward edge of the onset arc. Two THEMIS spacecraft encountered earthward flow bursts around the times the expanding optical aurora reached their magnetic footprints in the ionosphere. The particle and field measurements allowed for the reconstruction of the field-aligned current system and the determination of plasma properties in the auroral source region. Auroral arc properties were extracted from the optical and particle measurements and were used to compare measured values to theoretical predictions of the electrodynamic model for the generation of auroral arcs. Good agreement could be reached for the meso-scale arc properties. A qualitative analysis of the internal structuring of the bright onset arc suggests the operation of the tearing instability which provides a 'ropelike' appearance due to advection of the current in the sheared flow across the arc. We also note that for the observed parameters ionospheric conductivity gradients due to electron precipitation will be unstable to the feedback instability in the ionospheric Alfvén resonator that can drive structuring in luminosity over the range of scales observed.

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“…On 5 December 2007, the Reimei satellite (Saito et al, 2005) was moving from north to south and had a close conjunction with the EISCAT Tromsø radars from 00:36:35 to 00:36:45 UT, when the EISCAT UHF radar was running the arc1 modulation in the field-aligned direction. The modulation is an alternating code with 900 m height resolution and 4 s time resolution.…”

Section: Reimei Conjunction 5 December 2007mentioning

confidence: 99%

Electron Energy Spectrum and Auroral Power Estimation From Incoherent Scatter Radar Measurements

et al. 2018

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Differential energy flux of electrons precipitating into the high‐latitude ionosphere can be estimated from incoherent scatter radar observations of the ionospheric electron density profile. We present a method called ELSPEC for electron spectrum estimation from incoherent scatter radar measurements, which is based on integration of the electron continuity equation and spectrum model selection by means of the Akaike information criterion. This approach allows us to use data with almost arbitrary time resolutions, enables spectrum estimation with dense energy grids, avoids noise amplifications in numerical derivatives, and yields statistical error estimates for all the output parameters, including the number and energy fluxes and upward field‐aligned currents carried by the precipitating electrons. The technique is targeted for auroral energies, 1–100 keV, which ionize the atmosphere mainly between 80 and 150 km altitudes. We validate the technique by means of a simulation study, which shows that Maxwellian, kappa, and mono‐energetic spectra, as well as combinations of those, can be reproduced. Comparison study for two conjugate satellite measurements to the EISCAT UHF radar are shown, for Reimei and Swarm, showing an agreement with the results. Finally, an example of a 2‐hr measurement by the EISCAT radar is shown, during which we observe a variety of precipitation characteristics, from soft background precipitation to mono‐energetic spectra with peak energies up to 60 keV. The upward field‐aligned current varies from 0 to 10 μAm−2 and the total energy flux from 0 to 250 mWm−2.

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An Overview and Initial In-Orbit Status of INDEX S...

Cited by 7 publications

References 4 publications

Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

Small and meso‐scale properties of a substorm onset auroral arc

Electron Energy Spectrum and Auroral Power Estimation From Incoherent Scatter Radar Measurements

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