Naritoshi Kitamura
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View article: Characteristics of temporal and spatial variation of the electron density in the plasmasphere and ionosphere during the May 2024 super geomagnetic storm
Characteristics of temporal and spatial variation of the electron density in the plasmasphere and ionosphere during the May 2024 super geomagnetic storm Open
The spatial distribution of electron density in the ionosphere exhibits notable variability and undergoes considerable changes during storms and substorms driven by solar wind disturbances. Electron density variations and irregularities ca…
View article: Characteristics of temporal and spatial variation of the electron density in the plasmasphere and ionosphere during the May 2024 super geomagnetic storm
Characteristics of temporal and spatial variation of the electron density in the plasmasphere and ionosphere during the May 2024 super geomagnetic storm Open
The spatial distribution of electron density in the ionosphere exhibits notable variability and undergoes considerable changes during storms and substorms driven by solar wind disturbances. Electron density variations and irregularities ca…
View article: Arase In Situ Observations of High‐Frequency Electromagnetic Ion Cyclotron (EMIC) Waves in Regions Close to the Earth During the May 2024 Storm
Arase In Situ Observations of High‐Frequency Electromagnetic Ion Cyclotron (EMIC) Waves in Regions Close to the Earth During the May 2024 Storm Open
During the May 2024 storm, the minimum Dst index was approximately −412 nT, marking the largest geomagnetic storm of the past decade. This event caused the inner edge of the ring current to penetrate deeply into the inner magnetosphere dur…
View article: Arase Observations of the Radiation Belts During the May 2024 Geomagnetic Storm
Arase Observations of the Radiation Belts During the May 2024 Geomagnetic Storm Open
During the largest geomagnetic storm of Solar Cycle 25 that happened in May 2024, the Arase satellite has successfully operated all instruments and observed a number of remarkable phenomena in the inner magnetosphere and radiation belts. D…
View article: Solar wind driving of auroral outflow during a CME storm
Solar wind driving of auroral outflow during a CME storm Open
Data from the FAST spacecraft are used to study the temporal progression of the energy inputs to the dayside cusp and the nightside aurora, including Poynting flux, electron number flux and amplitude of extremely low frequency (ELF) waves,…
View article: A Study of Slow-mode Shocks in the Near-Earth Magnetotail with MMS Observations and Hybrid Simulations
A Study of Slow-mode Shocks in the Near-Earth Magnetotail with MMS Observations and Hybrid Simulations Open
The structure of the magnetic reconnection boundary, particularly the presence of slow-mode shocks in the near-Earth magnetotail was studied by using magnetospheric multiscale (MMS) observations and 2.5D hybrid simulations. A total of 51 c…
View article: Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted‐V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc
Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted‐V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc Open
We present an event based on Reimei satellite observations in the low‐altitude midnight auroral region, showing that intense and clear energy‐dispersed electron precipitations, repetitively generated by field‐aligned accelerations due to d…
View article: Statistical Observations of Proton‐Band Electromagnetic Ion Cyclotron Waves in the Outer Magnetosphere: Full Wavevector Determination
Statistical Observations of Proton‐Band Electromagnetic Ion Cyclotron Waves in the Outer Magnetosphere: Full Wavevector Determination Open
Electromagnetic Ion Cyclotron (EMIC) waves mediate energy transfer from the solar wind to the magnetosphere, relativistic electron precipitation, or thermalization of the ring current population, to name a few. How these processes take pla…
View article: Statistical Analysis of High-frequency Whistler Waves at Earth's Bow Shock: Further Support for Stochastic Shock Drift Acceleration
Statistical Analysis of High-frequency Whistler Waves at Earth's Bow Shock: Further Support for Stochastic Shock Drift Acceleration Open
We statistically investigate high-frequency whistler waves (with frequencies higher than $\sim 10$ % of the local elect ron cyclotron frequency) at Earth's bow shock using Magnetospheric Multi-Scale (MMS) spacecraft observations. We focus …
View article: Statistical analysis of high-frequency whistler waves at Earth's bow shock: Further support for stochastic shock drift acceleration
Statistical analysis of high-frequency whistler waves at Earth's bow shock: Further support for stochastic shock drift acceleration Open
We statistically investigate high-frequency whistler waves (with frequencies higher than ∼10% of the local electron cyclotron frequency) at Earth's bow shock using magnetospheric multi-scale (MMS) spacecraft observations. We focus specific…
View article: Cold ion heating in Earth’s magnetosphere
Cold ion heating in Earth’s magnetosphere Open
Whitepaper #405 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: space weather research/operations/research loop; system science; space-…
View article: The Critical Need for Innovations in Instruments and Techniques to Enable In-Situ Cold Ion and Cold Electron Measurements within the Magnetosphere
The Critical Need for Innovations in Instruments and Techniques to Enable In-Situ Cold Ion and Cold Electron Measurements within the Magnetosphere Open
Whitepaper #262 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: planetary magnetospheres; planetary ionospheres / upper atmospheres; ot…
View article: Source Data for Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth
Source Data for Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth Open
Source Data files for figures and Supplementary figures in the manuscript "Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth". Source_Data.zip includes data files (.txt or .xlsx…
View article: Source Data for Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth
Source Data for Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth Open
Source Data files for figures and Supplementary figures in the manuscript "Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth". Source_Data.zip includes data files (.txt or .xlsx…
View article: Kinetic Interaction of Cold and Hot Protons With an Oblique EMIC Wave Near the Dayside Reconnecting Magnetopause
Kinetic Interaction of Cold and Hot Protons With an Oblique EMIC Wave Near the Dayside Reconnecting Magnetopause Open
We report observations of the ion dynamics inside an Alfvén branch wave that propagates near the reconnecting dayside magnetopause. The measured frequency, wave normal angle and polarization are consistent with the predictions of a dispers…
View article: Energy Transfer Between Hot Protons and Electromagnetic Ion Cyclotron Waves in Compressional Pc5 Ultra‐low Frequency Waves
Energy Transfer Between Hot Protons and Electromagnetic Ion Cyclotron Waves in Compressional Pc5 Ultra‐low Frequency Waves Open
The Magnetospheric Multiscale (MMS) spacecraft observed many enhancements of electromagnetic ion cyclotron (EMIC) waves in an event in the late afternoon outer magnetosphere. These enhancements occurred mainly in the troughs of magnetic fi…
View article: Solar zenith angle dependence of relationships between energy inputs to the ionosphere and ion outflow fluxes
Solar zenith angle dependence of relationships between energy inputs to the ionosphere and ion outflow fluxes Open
The ionosphere is one of the important sources for magnetospheric plasma, particularly for heavy ions with low charge states. We investigate the effect of solar illumination on the number flux of ion outflow using data obtained by the Fast…
View article: Kinetic interaction of cold and hot protons with an oblique EMIC wave near the dayside reconnecting magnetopause
Kinetic interaction of cold and hot protons with an oblique EMIC wave near the dayside reconnecting magnetopause Open
<p>We report observations of the ion dynamics inside an Alfven branch wave that propagates near the reconnecting dayside magnetopause. The measured frequency, wave normal angle and polarization are within 1% with the predictions of a…
View article: Observations of the Source Region of Whistler Mode Waves in Magnetosheath Mirror Structures
Observations of the Source Region of Whistler Mode Waves in Magnetosheath Mirror Structures Open
In the magnetosheath, intense whistler mode waves, called “Lion roars,” are often detected in troughs of magnetic field intensity in mirror mode structures. Using data obtained by the four Magnetospheric Multiscale (MMS) spacecraft, we sho…
View article: Observational Evidence for Stochastic Shock Drift Acceleration of Electrons at the Earth’s Bow Shock
Observational Evidence for Stochastic Shock Drift Acceleration of Electrons at the Earth’s Bow Shock Open
The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidenc…
View article: Cusp and Nightside Auroral Sources of O<sup>+</sup> in the Plasma Sheet
Cusp and Nightside Auroral Sources of O<sup>+</sup> in the Plasma Sheet Open
Energetic O + outflow is observed from both the dayside cusp and the nightside aurora, but the relative importance of these regions in populating the plasma sheet and ring current is not known. During a storm on 16 July 2017, the Arase and…
View article: EMIC Waves Converted From Equatorial Noise Due to <i>M</i>/<i>Q</i> = 2 Ions in the Plasmasphere: Observations From Van Allen Probes and Arase
EMIC Waves Converted From Equatorial Noise Due to <i>M</i>/<i>Q</i> = 2 Ions in the Plasmasphere: Observations From Van Allen Probes and Arase Open
Equatorial noise (EN) emissions are observed inside and outside the plasmapause. EN emissions are referred to as magnetosonic mode waves. Using data from Van Allen Probes and Arase, we found conversion from EN emissions to electromagnetic …
View article: Direct measurements of two-way wave-particle energy transfer in a collisionless space plasma
Direct measurements of two-way wave-particle energy transfer in a collisionless space plasma Open
Two-step energy transfer in space plasma Plasmas are ionized gases that contain negative electrons, positive ions, and electromagnetic fields. These constituents can oscillate in position over time, carrying energy as plasma waves. In prin…
View article: Seasonal and Solar Wind Control of the Reconnection Line Location on the Earth's Dayside Magnetopause
Seasonal and Solar Wind Control of the Reconnection Line Location on the Earth's Dayside Magnetopause Open
We investigate the average location of magnetic reconnection on the Earth's dayside magnetopause, based on spatial distributions of northward and southward reconnection jets observed by the THEMIS spacecraft at the near‐noon (10–14 magneti…
View article: Inverse Energy Dispersion of Energetic Ions Observed in the Magnetosheath
Inverse Energy Dispersion of Energetic Ions Observed in the Magnetosheath Open
We present a case study of energetic ions observed by the Energetic Particle Detector (EPD) on the Magnetospheric Multiscale spacecraft in the magnetosheath just outside the subsolar magnetopause that occurred at 1000Â UT on 8 December 201…
View article: Inverse energy dispersion of energetic ions observed in the magnetosheath
Inverse energy dispersion of energetic ions observed in the magnetosheath Open
We present a case study of energetic ions observed by the Energetic Particle Detector (EPD) on the Magnetospheric Multiscale spacecraft in the magnetosheath just outside the subsolar magnetopause that occurred at 1000 UT on 8 December 2015…
View article: Thick escaping magnetospheric ion layer in magnetopause reconnection with MMS observations
Thick escaping magnetospheric ion layer in magnetopause reconnection with MMS observations Open
The structure of asymmetric magnetopause reconnection is explored with multiple point and high‐time‐resolution ion velocity distribution observations from the Magnetospheric Multiscale mission. On 9 September 2015, reconnection took place …
View article: Shift of the magnetopause reconnection line to the winter hemisphere under southward IMF conditions: Geotail and MMS observations
Shift of the magnetopause reconnection line to the winter hemisphere under southward IMF conditions: Geotail and MMS observations Open
At 02:13 UT on 18 November 2015 when the geomagnetic dipole was tilted by −27°, the MMS spacecraft observed southward reconnection jets near the subsolar magnetopause under southward and dawnward interplanetary magnetic field conditions. B…