2022/04/12 更新

写真a

ナカムラ サトコ
中村 紗都子
NAKAMURA Satoko
所属
高等研究院 特任助教
宇宙地球環境研究所 特任助教
職名
特任助教

学位 1

  1. 博士(理学) ( 2016年3月   京都大学 ) 

研究キーワード 4

  1. 磁気嵐

  2. 磁気圏物理

  3. 放射線帯

  4. 地磁気誘導電流

研究分野 1

  1. 自然科学一般 / 宇宙惑星科学

経歴 3

  1. 名古屋大学   宇宙地球環境研究所   特任助教

    2020年1月 - 現在

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    国名:日本国

  2. 京都大学   生存圏研究所   特任助教

    2019年6月 - 2020年1月

  3. 京都大学   生存圏研究所   研究員

    2016年4月 - 2019年5月

受賞 6

  1. 笹川科学研究奨励賞

    2020年4月   公益財団法人 日本科学協会   激甚宇宙天気災害時における地磁気誘導電流の日本電力供給へのリスク評価

    中村紗都子

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    受賞区分:出版社・新聞社・財団等の賞 

  2. 地球電磁気・地球惑星圏学会 学生発表賞 (オーロラメダル)

    2013年11月   地球電磁気・地球惑星圏学会   Sub-packet structures in the EMIC triggered emission observed by the THEMIS probes

    中村紗都子

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    受賞区分:国内学会・会議・シンポジウム等の賞 

  3. 2016 THEMIS SCIENCE NUGGETS

    2016年10月   NASA/THEMIS Mission   A statistical study of EMIC rising and falling tone emissions observed by THEMIS

    Satoko Nakamura

  4. 地球電磁気・地球惑星圏学会 優秀発表者

    2014年11月   地球電磁気・地球惑星圏学会   Correlation between relativistic electron flux and EMIC rising-tone emissions observed by the Van Allen Probes

    中村紗都子

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    受賞区分:国内学会・会議・シンポジウム等の賞 

  5. 京都大学理学研究科竹腰賞

    2013年3月   京都大学理学研究科   THEMIS衛星データを用いた電磁イオンサイクロトロントリガード・エミッションの解析

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    受賞区分:出版社・新聞社・財団等の賞 

  6. 京都大学大学院理学研究科地球惑星科学専攻修士論文賞

    京都大学大学院理学研究科   THEMIS衛星データを用いた電磁イオンサイクロトロントリガード・エミッションの解析

    中村紗都子

▼全件表示

 

論文 21

  1. PSTEP: project for solar–terrestrial environment prediction

    Kusano K., Ichimoto K., Ishii M., Miyoshi Y., Yoden S., Akiyoshi H., Asai A., Ebihara Y., Fujiwara H., Goto T.N., Hanaoka Y., Hayakawa H., Hosokawa K., Hotta H., Hozumi K., Imada S., Iwai K., Iyemori T., Jin H., Kataoka R., Katoh Y., Kikuchi T., Kubo Y., Kurita S., Matsumoto H., Mitani T., Miyahara H., Miyoshi Y., Nagatsuma T., Nakamizo A., Nakamura S., Nakata H., Nishizuka N., Otsuka Y., Saito S., Saito S., Sakurai T., Sato T., Shimizu T., Shinagawa H., Shiokawa K., Shiota D., Takashima T., Tao C., Toriumi S., Ueno S., Watanabe K., Watari S., Yashiro S., Yoshida K., Yoshikawa A.

    Earth, Planets and Space   73 巻 ( 1 )   2021年12月

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    記述言語:日本語   出版者・発行元:Earth, Planets and Space  

    Although solar activity may significantly impact the global environment and socioeconomic systems, the mechanisms for solar eruptions and the subsequent processes have not yet been fully understood. Thus, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project for solar–terrestrial environment prediction (PSTEP) was launched to improve this situation through synergy between basic science research and operational forecast. The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. By this project, we sought to answer the fundamental questions concerning the solar–terrestrial environment and aimed to build a next-generation space weather forecast system to prepare for severe space weather disasters. The PSTEP consists of four research groups and proposal-based research units. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.[Figure not available: see fulltext.]

    DOI: 10.1186/s40623-021-01486-1

    Scopus

  2. Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

    Miyoshi Y., Hosokawa K., Kurita S., Oyama S.I., Ogawa Y., Saito S., Shinohara I., Kero A., Turunen E., Verronen P.T., Kasahara S., Yokota S., Mitani T., Takashima T., Higashio N., Kasahara Y., Matsuda S., Tsuchiya F., Kumamoto A., Matsuoka A., Hori T., Keika K., Shoji M., Teramoto M., Imajo S., Jun C., Nakamura S.

    Scientific Reports   11 巻 ( 1 )   2021年12月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Scientific Reports  

    Pulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

    DOI: 10.1038/s41598-021-92611-3

    Scopus

    PubMed

  3. Correction to: ISEE_Wave: interactive plasma wave analysis tool (Earth, Planets and Space, (2021), 73, 1, (110), 10.1186/s40623-021-01430-3)

    Matsuda S., Miyoshi Y., Nakamura S., Kitahara M., Shoji M., Hori T., Imajo S., Jun C.W., Kurita S., Kasahara Y., Matsuoka A., Shinohara I.

    Earth, Planets and Space   73 巻 ( 1 )   2021年12月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Earth, Planets and Space  

    After publication of this article (Matsuda et al. 2021), it is noticed the 8th author’s name is incorrect. The name should be corrected from “Jun Chae-Woo” to “Chae-Woo Jun”. The name has been revised in this Correction and the original article has been updated as well.

    DOI: 10.1186/s40623-021-01450-z

    Web of Science

    Scopus

  4. ISEE_Wave: interactive plasma wave analysis tool

    Matsuda S., Miyoshi Y., Nakamura S., Kitahara M., Shoji M., Hori T., Imajo S., Chae-Woo J., Kurita S., Kasahara Y., Matsuoka A., Shinohara I.

    Earth, Planets and Space   73 巻 ( 1 )   2021年12月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Earth, Planets and Space  

    We have developed ISEE_Wave (Institute for Space-Earth Environmental Research, Nagoya University - Plasma Wave Analysis Tool), an interactive plasma wave analysis tool for electric and magnetic field waveforms observed by the plasma wave experiment aboard the Arase satellite. ISEE_Wave provides an integrated wave analysis environment on a graphical user interface, where users can visualize advanced wave properties, such as the electric and magnetic field wave power spectra, wave normal polar angle, polarization ellipse, planarity of polarization, and Poynting vector angle. Users can simply select a time interval for their analysis, and ISEE_Wave automatically downloads the waveform data, ambient magnetic field data, and spacecraft attitude data from the data archive repository of the ERG Science Center, and then performs necessary coordinate transformation and spectral matrix calculation. The singular value decomposition technique is used as the core technique for the wave property analysis of ISEE_Wave. On-demand analysis is possible by specifying the parameters of the wave property analysis as well as the plot styles using the graphical user interface of ISEE_Wave. The results can be saved as image files of plots and/or a tplot save file. ISEE_Wave aids in the identification of fine structures of observed plasma waves, wave mode identification, and wave propagation analysis. These properties can be used to understand plasma wave generation, propagation, and wave-particle interaction in the inner magnetosphere. ISEE_Wave can also be applied to general waveform data observed by other spacecraft by using the plug-in procedures to load the data. [Figure not available: see fulltext.]

    DOI: 10.1186/s40623-021-01430-3

    Web of Science

    Scopus

  5. Isolated Proton Aurora Driven by EMIC Pc1 Wave: PWING, Swarm, and NOAA POES Multi-Instrument Observations

    Kim H., Shiokawa K., Park J., Miyoshi Y., Miyashita Y., Stolle C., Connor H.K., Hwang J., Buchert S., Kwon H.J., Nakamura S., Nakamura K., Oyama S.I., Otsuka Y., Nagatsuma T., Sakaguchi K.

    Geophysical Research Letters   48 巻 ( 18 )   2021年9月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Geophysical Research Letters  

    We report the concurrent observations of F-region plasma changes and field-aligned currents (FACs) above isolated proton auroras (IPAs) associated with electromagnetic ion cyclotron Pc1 waves. Key events on March 19, 2020 and September 12, 2018 show that ground magnetometers and all-sky imagers detected concurrent Pc1 wave and IPA, during which NOAA POES observed precipitating energetic protons. In the ionospheric F-layer above the IPA zone, the Swarm satellites observed transverse Pc1 waves, which span wider latitudes than IPA. Around IPA, Swarm also detected the bipolar FAC and localized plasma density enhancement, which is occasionally surrounded by wide/shallow depletion. This indicates that wave-induced proton precipitation contributes to the energy transfer from the magnetosphere to the ionosphere.

    DOI: 10.1029/2021GL095090

    Scopus

  6. First Simultaneous Observation of a Night Time Medium-Scale Traveling Ionospheric Disturbance From the Ground and a Magnetospheric Satellite

    Kawai K., Shiokawa K., Otsuka Y., Oyama S., Kasaba Y., Kasahara Y., Tsuchiya F., Kumamoto A., Nakamura S., Matsuoka A., Imajo S., Kazama Y., Wang S.Y., Tam S.W.Y., Chang T.F., Wang B.J., Asamura K., Kasahara S., Yokota S., Keika K., Hori T., Miyoshi Y., Jun C., Shoji M., Shinohara I.

    Journal of Geophysical Research: Space Physics   126 巻 ( 9 )   2021年9月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    Medium-scale traveling ionospheric disturbances (MSTIDs) are a phenomenon widely and frequently observed over the ionosphere from high to low latitudes. Night time MSTIDs are caused generally by the polarization electric field in the ionosphere. However, propagation of this polarization electric field to the magnetosphere has not yet been identified. Here, we report the first observation of the polarization electric field and associated density variations of a night time MSTID in the magnetosphere. The MSTID event was observed by an all-sky airglow imager at Gakona (geographical latitude: 62.39°N, geographical longitude: 214.78°E, magnetic latitude: 63.20°N), Alaska. The Arase satellite passed over the MSTID in the inner magnetosphere at 0530–0800 UT (2030–2300 LT) on November 3, 2018. This MSTID, observed in 630 nm airglow images, was propagating westward with a horizontal wavelength of ∼165 km, a north–south phase front, and a phase velocity of ∼80 m/s. The Arase satellite footprint on the ionosphere crossed the MSTID in the direction nearly perpendicular to the MSTID phase fronts. The electric field and electron density observed by the Arase satellite showed periodic variation associated with the MSTID structure with amplitudes of ∼2 mV/m and ∼150 cm−3, respectively. The electric field variations projected to the ionosphere are mainly in the east-west direction and are consistent with the direction of the polarization electric field expected from MSTID growth by E × B drift. This observation indicates that the polarization electric field associated with the MSTID in the ionosphere is projected onto the magnetosphere, causing plasma density fluctuations in the magnetosphere.

    DOI: 10.1029/2020JA029086

    Scopus

  7. Evening Side EMIC Waves and Related Proton Precipitation Induced by a Substorm

    Yahnin A.G., Popova T.A., Demekhov A.G., Lubchich A.A., Matsuoka A., Asamura K., Miyoshi Y., Yokota S., Kasahara S., Keika K., Hori T., Tsuchiya F., Kumamoto A., Kasahara Y., Shoji M., Kasaba Y., Nakamura S., Shinohara I., Kim H., Noh S., Raita T.

    Journal of Geophysical Research: Space Physics   126 巻 ( 7 )   2021年7月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    We present the results of a multi-point and multi-instrument study of electromagnetic ion cyclotron (EMIC) waves and related energetic proton precipitation during a substorm. We analyze the data from Arase (ERG) and Van Allen Probes (VAPs) A and B spacecraft for an event of 16 and 17 UT on December 1, 2018. VAP-A detected an almost dispersionless injection of energetic protons related to the substorm onset in the night sector. Then the proton injection was detected by VAP-B and further by Arase, as a dispersive enhancement of energetic proton flux. The proton flux enhancement at every spacecraft coincided with the EMIC wave enhancement or appearance. This data show the excitation of EMIC waves first inside an expanding substorm wedge and then by a drifting cloud of injected protons. Low-orbiting NOAA/POES and MetOp satellites observed precipitation of energetic protons nearly conjugate with the EMIC wave observations in the magnetosphere. The proton pitch-angle diffusion coefficient and the strong diffusion regime index were calculated based on the observed wave, plasma, and magnetic field parameters. The diffusion coefficient reaches a maximum at energies corresponding well to the energy range of the observed proton precipitation. The diffusion coefficient values indicated the strong diffusion regime, in agreement with the equality of the trapped and precipitating proton flux at the low-Earth orbit. The growth rate calculations based on the plasma and magnetic field data from both VAP and Arase spacecraft indicated that the detected EMIC waves could be generated in the region of their observation or in its close vicinity.

    DOI: 10.1029/2020JA029091

    Scopus

  8. The Characteristics of EMIC Waves in the Magnetosphere Based on the Van Allen Probes and Arase Observations

    Jun C.W., Miyoshi Y., Kurita S., Yue C., Bortnik J., Lyons L., Nakamura S., Shoji M., Imajo S., Kletzing C., Kasahara Y., Kasaba Y., Matsuda S., Tsuchiya F., Kumamoto A., Matsuoka A., Shinohara I.

    Journal of Geophysical Research: Space Physics   126 巻 ( 6 )   2021年6月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    We performed a comprehensive statistical study of electromagnetic ion cyclotron (EMIC) waves observed by the Van Allen Probes and Exploration of energization and Radiation in Geospace satellite (ERG/Arase). From 2017 to 2018, we identified and categorized EMIC wave events with respect to wavebands (H+ and He+ EMIC waves) and relative locations from the plasmasphere (inside and outside the plasmasphere). We found that H+ EMIC waves in the morning sector at L > 8 are predominantly observed with a mixture of linear and right-handed polarity and higher wave normal angles during quiet geomagnetic conditions. Both H+ and He+ EMIC waves observed in the noon sector at L ∼ 4–6 have left-handed polarity and lower wave normal angles at |MLAT| < 20° during the recovery phase of a storm with moderate solar wind pressure. In the afternoon sector (12–18 MLT), He+ EMIC waves are dominantly observed with strongly enhanced wave power at L ∼ 6–8 during the storm main phase, while in the dusk sector (17–21 MLT) they have lower wave normal angles with linear polarity at L > 8 during geomagnetic quiet conditions. Based on distinct characteristics at different EMIC wave occurrence regions, we suggest that EMIC waves in the magnetosphere can be generated by different free energy sources. Possible sources include the freshly injected particles from the plasma sheet, adiabatic heating by dayside magnetospheric compressions, suprathermal proton heating by magnetosonic waves, and off-equatorial sources.

    DOI: 10.1029/2020JA029001

    Scopus

  9. Measurement of geomagnetically induced current (GIC) around Tokyo, Japan

    Watari S., Nakamura S., Ebihara Y.

    Earth, Planets and Space   73 巻 ( 1 )   2021年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Earth, Planets and Space  

    We need a typical method of directly measuring geomagnetically induced current (GIC) to compare data for estimating a potential risk of power grids caused by GIC. Here, we overview GIC measurement systems that have appeared in published papers, note necessary requirements, report on our equipment, and show several examples of our measurements in substations around Tokyo, Japan. Although they are located at middle latitudes, GICs associated with various geomagnetic disturbances are observed, such as storm sudden commencements (SSCs) or sudden impulses (SIs) caused by interplanetary shocks, geomagnetic storms including a storm caused by abrupt southward turning of strong interplanetary magnetic field (IMF) associated with a magnetic cloud, bay disturbances caused by high-latitude aurora activities, and geomagnetic variation caused by a solar flare called the solar flare effect (SFE). All these results suggest that GIC at middle latitudes is sensitive to the magnetospheric current (the magnetopause current, the ring current, and the field-aligned current) and also the ionospheric current. [Figure not available: see fulltext.]

    DOI: 10.1186/s40623-021-01422-3

    Web of Science

    Scopus

  10. Energy Transfer Between Hot Protons and Electromagnetic Ion Cyclotron Waves in Compressional Pc5 Ultra-low Frequency Waves

    Kitamura N., Shoji M., Nakamura S., Kitahara M., Amano T., Omura Y., Hasegawa H., Boardsen S.A., Miyoshi Y., Katoh Y., Teramoto M., Saito Y., Yokota S., Hirahara M., Gershman D.J., Giles B.L., Russell C.T., Strangeway R.J., Ahmadi N., Lindqvist P.A., Ergun R.E., Fuselier S.A., Burch J.L.

    Journal of Geophysical Research: Space Physics   126 巻 ( 5 )   2021年5月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    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 field intensity associated with a compressional ultralow frequency (ULF) wave. The ULF wave had a period of ∼2–5 min (Pc5 frequency range) and was almost static in the plasma rest frame. The magnetic and ion pressures were in antiphase. They are consistent with mirror-mode type structures. We apply the Wave-Particle Interaction Analyzer method, which can quantitatively investigate the energy transfer between hot anisotropic protons and EMIC waves, to burst-mode data obtained by the four MMS spacecraft. The energy transfer near the cyclotron resonance velocity was identified in the vicinity of the center of troughs of magnetic field intensity, which corresponds to the maxima of ion pressure in the compressional ULF wave. This result is consistent with the idea that the EMIC wave generation is modulated by ULF waves, and preferential locations for the cyclotron resonant energy transfer are the troughs of magnetic field intensity. In these troughs, relatively low resonance velocity due to the lower magnetic field intensity and the enhanced hot proton flux likely contribute to the enhanced energy transfer from hot protons to the EMIC waves by cyclotron resonance. Due to the compressional ULF wave, regions of the cyclotron resonant energy transfer can be narrow (only a few times of the gyroradii of hot resonant protons) in magnetic local time.

    DOI: 10.1029/2020JA028912

    Scopus

  11. Multi-Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non-Storm-Time Substorms

    Inaba Y., Shiokawa K., Oyama S.i., Otsuka Y., Connors M., Schofield I., Miyoshi Y., Imajo S., Shinbori A., Gololobov A.Y., Kazama Y., Wang S.Y., Tam S.W.Y., Chang T.F., Wang B.J., Asamura K., Yokota S., Kasahara S., Keika K., Hori T., Matsuoka A., Kasahara Y., Kumamoto A., Matsuda S., Kasaba Y., Tsuchiya F., Shoji M., Kitahara M., Nakamura S., Shinohara I., Spence H.E., Reeves G.D., Macdowall R.J., Smith C.W., Wygant J.R., Bonnell J.W.

    Journal of Geophysical Research: Space Physics   126 巻 ( 4 )   2021年4月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This work studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and Radiation Belt Storm Probes [RBSP]) during non-storm-time substorms on December 19, 2012 (event 1), January 17, 2015 (event 2), and November 4, 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly detached SAR arc.

    DOI: 10.1029/2020JA029081

    Scopus

  12. Data-Driven Simulation of Rapid Flux Enhancement of Energetic Electrons With an Upper-Band Whistler Burst

    Saito S., Kurita S., Miyoshi Y., Kasahara S., Yokota S., Keika K., Hori T., Kasahara Y., Matsuda S., Shoji M., Nakamura S., Matsuoka A., Imajo S., Shinohara I.

    Journal of Geophysical Research: Space Physics   126 巻 ( 4 )   2021年4月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    The temporal variation of the energetic electron flux distribution caused by whistler mode chorus waves through the cyclotron resonant interaction provides crucial information on how electrons are accelerated in the Earth's inner magnetosphere. This study employs a data-driven test-particle simulation which demonstrates that the rapid change of energetic electron distribution observed by the Arase satellite cannot be simply explained by a quasi-linear diffusion mechanism, but is essentially caused by nonlinear scattering: the phase trapping and the phase dislocation. In response to upper-band whistler chorus bursts, multiple nonlinear interactions finally achieve an efficient flux enhancement of electrons on a time scale of the chorus burst. A quasi-linear diffusion model tends to underestimate the flux enhancement of energetic electrons as compared with a model based on the realistic dynamic frequency spectrum of whistler waves. It is concluded that the nonlinear phase trapping plays an important role in the rapid flux enhancement of energetic electrons observed by Arase.

    DOI: 10.1029/2020JA028979

    Scopus

  13. Active auroral arc powered by accelerated electrons from very high altitudes.

    Imajo S, Miyoshi Y, Kazama Y, Asamura K, Shinohara I, Shiokawa K, Kasahara Y, Kasaba Y, Matsuoka A, Wang SY, Tam SWY, Chang TF, Wang BJ, Angelopoulos V, Jun CW, Shoji M, Nakamura S, Kitahara M, Teramoto M, Kurita S, Hori T

    Scientific reports   11 巻 ( 1 ) 頁: 1610   2021年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Scientific Reports  

    Bright, discrete, thin auroral arcs are a typical form of auroras in nightside polar regions. Their light is produced by magnetospheric electrons, accelerated downward to obtain energies of several kilo electron volts by a quasi-static electric field. These electrons collide with and excite thermosphere atoms to higher energy states at altitude of ~ 100 km; relaxation from these states produces the auroral light. The electric potential accelerating the aurora-producing electrons has been reported to lie immediately above the ionosphere, at a few altitudes of thousand kilometres1. However, the highest altitude at which the precipitating electron is accelerated by the parallel potential drop is still unclear. Here, we show that active auroral arcs are powered by electrons accelerated at altitudes reaching greater than 30,000 km. We employ high-angular resolution electron observations achieved by the Arase satellite in the magnetosphere and optical observations of the aurora from a ground-based all-sky imager. Our observations of electron properties and dynamics resemble those of electron potential acceleration reported from low-altitude satellites except that the acceleration region is much higher than previously assumed. This shows that the dominant auroral acceleration region can extend far above a few thousand kilometres, well within the magnetospheric plasma proper, suggesting formation of the acceleration region by some unknown magnetospheric mechanisms.

    DOI: 10.1038/s41598-020-79665-5

    Scopus

    PubMed

  14. Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

    三好 由純, 細川 敬祐, 栗田 怜, 大山 伸一郎, 小川 泰信, 齊藤 慎司, 篠原 育, Kero A., Turunen E., Verronen P. T., 笠原 慧, 横田 勝一郎, 三谷 烈史, 高島 健, 東尾 奈々, 笠原 禎也, 松田 昇也, 土屋 史紀, 熊本 篤志, 松岡 彩子, 堀 智昭, 桂華 邦裕, 小路 真史, 寺本 万里子, 今城 峻, Jun C., 中村 紗都子

    Scientific Reports   ( 11 )   2021年

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    記述言語:英語   出版者・発行元:Springer Nature  

    明滅オーロラとともに起こるオゾン破壊 --宇宙からの高エネルギー電子が大気に及ぼす影響を実証--. 京都大学プレスリリース. 2021-07-14.

  15. Full Particle Simulation of Whistler-Mode Triggered Falling-Tone Emissions in the Magnetosphere

    Takeshi Nogi, Satoko Nakamura, Yoshiharu Omura

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   125 巻 ( 10 )   2020年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    We perform a one-dimensional electromagnetic full particle simulation for triggered falling-tone emissions in the Earth's magnetosphere. The equatorial region of the magnetosphere is modeled with a parabolic magnetic field approximation. The short whistler-mode waves with a large amplitude are excited and propagate poleward from an artificial current oscillating with a constant frequency and amplitude. Following the excited waves, clear emissions are triggered with a falling frequency. Without the inhomogeneity of the background magnetic field, no triggered emission appears. The falling tone has several subpackets of amplitude and decreases the frequency in a stepwise manner. The positive resonant current formed by resonant electrons in the direction of the wave magnetic field clearly shows that an electron hill is formed in the phase space and causes the frequency decrease. The entrapping of the resonant electrons at the front of the packets and the decrease of the amplitude at the end of packets are essential for the generation of falling-tone emissions. Each wavefront of the emission has a strongly negative resonant current -J(E), which results in the wave growth. In the formation process of the resonant currents, we investigate the inhomogeneous factor S, which controls the nonlinear motion of the resonant electrons interacting with waves. The factor S consists of two terms, a frequency sweep rate and a gradient of the background magnetic field. The resonant current J(E) in the wave packet changes its sign from negative to positive as the packet moves away from the equator, terminating the wave growth.

    DOI: 10.1029/2020JA027953

    Web of Science

    Scopus

  16. Observations of the Source Region of Whistler Mode Waves in Magnetosheath Mirror Structures

    Kitamura N., Omura Y., Nakamura S., Amano T., Boardsen S.A., Ahmadi N., Le Contel O., Lindqvist P.A., Ergun R.E., Saito Y., Yokota S., Gershman D.J., Paterson W.R., Pollock C.J., Giles B.L., Russell C.T., Strangeway R.J., Burch J.L.

    Journal of Geophysical Research: Space Physics   125 巻 ( 5 )   2020年5月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Geophysical Research: Space Physics  

    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 show that reversals of gradient of magnetic field intensity along the magnetic field correspond to reversals of the field-aligned component of Poynting flux of whistler mode waves in the troughs. Such a characteristic is consistent with the idea that the whistler mode waves are effectively generated near the local minima of magnetic field intensity because of the smallest cyclotron resonance velocity and propagate toward regions of larger magnetic field intensity along the magnetic field lines on both sides. We use the reversal of the Poynting flux as an indicator of wave source regions. In these regions, we find that pancake or an outer edge of butterfly electron distributions above ~100 eV are good candidates for wave generation. Unclear correlations of phase difference and amplitude variations of whistler mode waves in cases of ~40 km spacecraft separation indicate that a simple plane wave approximation with a constant amplitude is not valid at this spatial scale that is much smaller than the ion gyroradius. The whistler mode waves consist of small coherent wave packets from multiple sources with spatial scales smaller than tens of electron gyroradii transverse to the background magnetic field in a mirror mode structure.

    DOI: 10.1029/2019JA027488

    Scopus

  17. Rapid Precipitation of Relativistic Electron by EMIC Rising-Tone Emissions Observed by the Van Allen Probes

    S. Nakamura, Y. Omura, C. Kletzing, D. N. Baker

    Journal of Geophysical Research: Space Physics   124 巻 ( 8 ) 頁: 6701 - 6714   2019年8月

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    掲載種別:研究論文(学術雑誌)  

    On 23 February 2014, Van Allen Probes sensors observed quite strong electromagnetic ion cyclotron (EMIC) waves in the outer dayside magnetosphere. The maximum amplitude was more than 14 nT, comparable to 7% of the magnitude of the ambient magnetic field. The EMIC waves consisted of a series of coherent rising tone emissions. Rising tones are excited sporadically by energetic protons. At the same time, the probes detected drastic fluctuations in fluxes of MeV electrons. It was found that the electron fluxes decreased by more than 30% during the 1 min following the observation of each EMIC rising tone emissions. Furthermore, it is concluded that the flux reduction is a nonadiabatic (irreversible) process since holes in the particle flux levels appear as drift echoes with energy dispersion. We examine the process of electron pitch angle scattering by nonlinear wave trapping due to anomalous cyclotron resonance with EMIC rising tone emissions. The energy range of precipitated electrons agrees with the presumed energy for the threshold amplitude for nonlinear wave trapping. This is the first report of rapid precipitation ('1 min) of relativistic electrons by EMIC rising tone emissions and their drift echoes in time observed by spacecraft.

    DOI: 10.1029/2019JA026772

    Scopus

  18. Time Domain Simulation of Geomagnetically Induced Current (GIC) Flowing in 500-kV Power Grid in Japan Including a Three-Dimensional Ground Inhomogeneity

    S. Nakamura, Y. Ebihara, S. Fujita, T. Goto, N. Yamada, S. Watari, Y. Omura

    Space Weather   16 巻 ( 12 ) 頁: 1946 - 1959   2018年12月

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    掲載種別:研究論文(学術雑誌)  

    We performed 3-D time domain simulation of geomagnetically induced currents (GICs) flowing in the Japanese 500-kV power grid. The three-dimensional distribution of the geomagnetically induced electric field (GIE) was calculated by using the finite difference time domain method with a three-dimensional electrical conductivity model constructed from a global relief model and a global map of sediment thickness. First, we imposed a uniform sheet current at 100-km altitude with a sinusoidal perturbation to illuminate the influence of the structured ground conductivity on GIE and GIC. The simulation result shows that GIE exhibits localized, uneven distribution that can be attributed to charge accumulation due to the inhomogeneous conductivity below the Earth's surface. The charge accumulation becomes large when the conductivity gradient vector is parallel or antiparallel to the incident electric field. For given GIE, we calculated the GICs flowing in a simplified 500-kV power grid network in Japan. The influence of the inhomogeneous ground conductivity on GIC appears to depend on a combination of the location of substations and the direction of the source current. Uneven distribution of the power grid system gives rise to intensification of the GICs flowing in remote areas where substations/power plants are distributed sparsely. Second, we imposed the sheet current with its intensity inferred from the ground magnetic disturbance for the magnetic storm of 27 May 2017. We compared the calculated GICs with the observed ones at substations around Tokyo and found a certain agreement when the uneven distribution of GIE is incorporated with the simulation.

    DOI: 10.1029/2018SW002004

    Scopus

  19. Fine Structure of Whistler Mode Hiss in Plasmaspheric Plumes Observed by the Van Allen Probes

    S. Nakamura, Y. Omura, D. Summers

    Journal of Geophysical Research: Space Physics   123 巻 ( 11 ) 頁: 9055 - 9064   2018年11月

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    掲載種別:研究論文(学術雑誌)  

    We survey 3 years (2013–2015) of data from the Van Allen Probes related to plasmaspheric plume crossing events. We detect 194 plume crossing events, and we find that 97% of the plumes are accompanied by very low frequency hiss emissions. The plumes are mainly detected on the duskside or dayside. Careful examination of the hiss spectra reveals that all hiss emissions consist of obvious fine structure. Application of a band-pass filter reveals that the fine structure is consistent with the occurrence of discrete wave packets. The hiss data display high coherency. The events are classified by location. Duskside hiss and nightside hiss tend to have extremely high polarization with no chorus at the high-frequency end of the dynamic spectrum. The duskside hiss has a distinct upper frequency limit. On the other hand, the dawnside hiss has strong chorus elements at the upper hiss frequency, which makes the upper frequency limit ambiguous. We show that the structure of whistler mode hiss is different from artificial random noise. Although noise also has fine spectral characteristics, the polarization and waveform data are totally different from the hiss cases. Our results strongly suggest that whistler mode hiss in plasmaspheric plumes universally possesses fine structure.

    DOI: 10.1029/2018JA025803

    Scopus

  20. Direct measurements of two-way wave-particle energy transfer in a collisionless space plasma

    N. Kitamura, M. Kitahara, M. Shoji, Y. Miyoshi, H. Hasegawa, S. Nakamura, Y. Katoh, Y. Saito, S. Yokota, D. J. Gershman, A. F. Vinas, B. L. Giles, T. E. Moore, W. R. Paterson, C. J. Pollock, C. T. Russell, R. J. Strangeway, S. A. Fuselier, J. L. Burch

    Science   361 巻 ( 6406 ) 頁: 1000 - 1003   2018年9月

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    掲載種別:研究論文(学術雑誌)  

    Particle acceleration by plasma waves and spontaneous wave generation are fundamental energy and momentum exchange processes in collisionless plasmas. Such wave-particle interactions occur ubiquitously in space. We present ultrafast measurements in Earth’s magnetosphere by the Magnetospheric Multiscale spacecraft that enabled quantitative evaluation of energy transfer in interactions associated with electromagnetic ion cyclotron waves. The observed ion distributions are not symmetric around the magnetic field direction but are in phase with the plasma wave fields. The wave-ion phase relations demonstrate that a cyclotron resonance transferred energy from hot protons to waves, which in turn nonresonantly accelerated cold He+ to energies up to ~2 kilo–electron volts. These observations provide direct quantitative evidence for collisionless energy transfer in plasmas between distinct particle populations via wave-particle interactions.

    DOI: 10.1126/science.aap8730

    Scopus

    PubMed

  21. Ion hole formation and nonlinear generation of electromagnetic ion cyclotron waves: THEMIS observations

    Masafumi Shoji, Yoshizumi Miyoshi, Yuto Katoh, Kunihiro Keika, Vassilis Angelopoulos, Satoshi Kasahara, Kazushi Asamura, Satoko Nakamura, Yoshiharu Omura

    GEOPHYSICAL RESEARCH LETTERS   44 巻 ( 17 ) 頁: 8730 - 8738   2017年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyromotion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion holes in the distribution function and the resulting nonlinear EMIC wave evolution from Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave-particle interactions, which are identified by a computer simulation in this study.

    DOI: 10.1002/2017GL074254

    Web of Science

    Scopus

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書籍等出版物 1

  1. 太陽地球圏環境予測 オープン・テキストブック(PSTEP Open Textbook) 2-3-1.GIC発生のメカニズム (2-3.地磁気変動とGIC)

    中村, 紗都子 , 後藤, 忠徳( 担当: 共著 ,  範囲: 全文)

    名古屋大学レポジトリ  2021年5月 

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    記述言語:日本語 著書種別:学術書

    DOI: 10.18999/pstep.2021.2.3.1

MISC 3

  1. PSTEP: project for solar–terrestrial environment prediction

    Kusano K., Ichimoto K., Ishii M., Miyoshi Y., Yoden S., Akiyoshi H., Asai A., Ebihara Y., Fujiwara H., Goto T.N., Hanaoka Y., Hayakawa H., Hosokawa K., Hotta H., Hozumi K., Imada S., Iwai K., Iyemori T., Jin H., Kataoka R., Katoh Y., Kikuchi T., Kubo Y., Kurita S., Matsumoto H., Mitani T., Miyahara H., Miyoshi Y., Nagatsuma T., Nakamizo A., Nakamura S., Nakata H., Nishizuka N., Otsuka Y., Saito S., Saito S., Sakurai T., Sato T., Shimizu T., Shinagawa H., Shiokawa K., Shiota D., Takashima T., Tao C., Toriumi S., Ueno S., Watanabe K., Watari S., Yashiro S., Yoshida K., Yoshikawa A.  

    Earth, Planets and Space73 巻 ( 1 )   2021年12月

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    記述言語:日本語   掲載種別:速報,短報,研究ノート等(学術雑誌)   出版者・発行元:Earth, Planets and Space  

    Although solar activity may significantly impact the global environment and socioeconomic systems, the mechanisms for solar eruptions and the subsequent processes have not yet been fully understood. Thus, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project for solar–terrestrial environment prediction (PSTEP) was launched to improve this situation through synergy between basic science research and operational forecast. The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. By this project, we sought to answer the fundamental questions concerning the solar–terrestrial environment and aimed to build a next-generation space weather forecast system to prepare for severe space weather disasters. The PSTEP consists of four research groups and proposal-based research units. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.[Figure not available: see fulltext.]

    DOI: 10.1186/s40623-021-01486-1

    Scopus

  2. 太陽地球圏環境予測 オープン・テキストブック(PSTEP Open Textbook) 2-3-1.GIC発生のメカニズム (2-3.地磁気変動とGIC)

    中村, 紗都子, 後藤, 忠徳  

        2021年10月

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    担当区分:責任著者  

  3. 宇宙擾乱と地磁気誘導電流

    海老原祐輔 , 石井守 , 亘慎一 , 後藤忠徳 , 藤田茂 , 菊池崇 , 田中高史 , 久保田康文 , 吉川顕正 , 片岡龍峰 , 吉村純 , 中村紗都子  

    宇宙科学技術連合講演会講演集(CD-ROM)S0277B 巻   2016年

講演・口頭発表等 10

  1. 地球磁気圏におけるサイクロトロン共鳴の観測的課題 招待有り

    中村紗都子

    プラズマ科学のフロンティア2020研究会  2021年3月7日 

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    会議種別:口頭発表(基調)  

  2. Time domain simulation of GIC flowing in power grid in Japan 招待有り

    Nakamura, S, Ebihara, Y, Fujita, S, Goto, T, Yamada, N, Watari, S, Omura, Y

    The Fourteenth Edition of the Solar-Terrestrial Physics Symposium (STP14)  2018年7月 

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    会議種別:口頭発表(招待・特別)  

  3. Time Domain Simulation of Geomagnetically Induced Current (GIC) Flowing in 500‐kV Power Grid in Japan Including a Three‐Dimensional Ground Inhomogeneity 招待有り

    Nakamura, S, Ebihara, Y, Fujita, S, Goto, T, Yamada, N, Watari, S, Omura, Y

    The 3rd PSTEP International Symposium (PSTEP-3) “Toward the Solar-Terrestrial Environment Prediction as Science and Social Infrastructure  2018年5月 

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    会議種別:口頭発表(招待・特別)  

  4. Time domain simulation of geomagnetically induced current (GIC) flowing in 500 kV power grid in Japan including a three-dimensional ground inhomogeneity 招待有り

    Nakamura, S, Ebihara, Y, Fujita, S, Goto, T, Yamada, N, Watari, S, Omura, Y

    AGU Fall Meeting  2018年12月 

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    会議種別:口頭発表(招待・特別)  

  5. Simulation of Geomagnetically Induced Current (GIC) Flowing in Japanese Power Grid 招待有り

    Satoko Nakamura, Yusuke Ebihara, Shinichi Watari

    PSTEP Science meeting “Prospects of Modeling Studies for Solar-Terrestrial Environment Prediction  2018年2月 

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    会議種別:口頭発表(招待・特別)  

  6. Simulation of Geomagnetically Induced Current (GIC) Flowing in 500 kV Power Grid in Japan Including a Three-dimensional Ground Inhomogeneity 招待有り

    Nakamura, S, Ebihara, Y, Fujita, S, Goto, T, Yamada, N, Watari, S, Omura, Y

    Asia Oceania Geosciences Society (AOGS) 16th Annual Meeting  2019年7月 

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    会議種別:口頭発表(招待・特別)  

  7. Modelling geomagnetically induced currents (GIC) in the 500 kV power grid in Japan produced by realistic electric fields 招待有り

    中村紗都子, 海老原祐輔, 藤田茂, 後藤忠徳, 亘慎一, 大村善治

    JpGU-AGU Joint Meeting 2017  2017年5月 

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    会議種別:口頭発表(招待・特別)  

  8. Modelling geomagnetically induced currents (GIC) in the 500 kV power grid in Japan produced by realistic electric fields 招待有り

    Nakamura, S, Ebihara, Y, Fujita, S, Goto, T, Yamada, N, Watari, S

    JpGU-AGU Joint Meeting  2019年5月 

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    会議種別:口頭発表(招待・特別)  

  9. Modeling geomagnetically induced currents (GIC) in the 500 kV power grid in Japan 招待有り

    中村紗都子, 海老原祐輔, 藤田茂, 後藤忠徳, 亘慎一, 大村善治

    第142回地球電磁気・地球惑星圏学会  2017年10月 

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    会議種別:口頭発表(招待・特別)  

  10. Development of prediction model of Japanese GIC 招待有り

    Satoko Nakamura, Yusuke Ebihara, Shinichi Watari

    The 4th PSTEP International Symposium (PSTEP-4) and the 2nd ISEE Symposium  2020年1月 

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    会議種別:口頭発表(招待・特別)  

▼全件表示

科研費 1

  1. 新たな宇宙プラズマ観測手法「ドリフトエコーモニター」の提案と実証

    研究課題/研究課題番号:21K13978  2021年4月 - 2024年3月

    日本学術振興会  科学研究費助成事業  若手研究

    中村 紗都子

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    担当区分:研究代表者 

    配分額:4680000円 ( 直接経費:3600000円 、 間接経費:1080000円 )

    本研究の目的は「粒子ドリフトエコーホール」という現象を応用した宇宙プラズマの新たな観測手法の提唱および地球磁気圏での実証である。ドリフトエコーホールは申請者が観測例を初めて発見し報告したもので、磁気圏の局所かつ散発的な粒子加速の影響がドリフト下流で特徴的なフラックスとして検出されるものである。ドリフトエコーは上流の加速機構とドリフト中の背景プラズマの情報を含んでいるため、本申請ではエコーを磁気圏全体のモニターとして応用する手法を考案する。またその有用性の実証として地球磁気圏の各種素過程と放射線帯ダイナミクスの定量評価を試みる。

 

メディア報道 3

  1. 太陽フレア、海側に停電リスク 京大が数理モデル 新聞・雑誌

    京都新聞  2017年10月

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    執筆者:本人以外 

  2. 京大院リケジョが講演滋賀産業人クラブ会員交流会

    日刊工業新聞  2017年3月

  3. それゆけ宇宙開発、滋賀産業人クラブ会員交流会 新聞・雑誌

    日刊工業新聞  2016年3月

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    執筆者:本人以外