Updated on 2024/03/28

写真a

 
IEDA, Akimasa
 
Organization
Institute for Space-Earth Environmental Research Division for Integrated Studies Assistant Professor
Graduate School
Graduate School of Science
Title
Assistant Professor
Contact information
メールアドレス
Homepage
http://www.isee.nagoya-u.ac.jp/~ieda/en/

Degree 1

  1. 博士（理学） （ 1998.3   京都大学 ） 

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Research Interests 13

  1. magnetic reconnection

  2. plasmoid

  3. magnetosphere

  4. ionosphere

  5. substorm

  6. auroral breakup

  7. aurora

  8. aurora

  9. auroral breakup

  10. magnetosphere

  11. magnetic reconnection

  12. plasmoid

  13. substorm

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Research Areas 2

  1. Others / Others  / Space physics

  2. Natural Science / Space and planetary sciences

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Current Research Project and SDGs 2

  1. 地磁気逆計算法を用いたオーロラ電流系の解明

  2. 衛星観測と地磁気逆計算法によるオーロラ爆発開始条件の解明

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Research History 6

  1. Nagoya University   Solar-Terrestrial Environment Laboratory Division IV: Integrated Studies   Assistant Professor

    2007.4 - 2015.9

  2. Nagoya University   Solar-Terrestrial Environment Laboratory Division IV: Integrated Studies   Assistant

    2003.2 - 2007.3

  3. 宇宙科学研究所

    2001.4 - 2003.2

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    Country：Japan

  4. 宇宙科学研究所・日本学術振興会特別研究員PD

    2001.4 - 2003.2

  5. NASA Goddard space flight center

    1998.7 - 2001.3

  6. NASA Goddard space flight center / NRC research associate

    1998.7 - 2001.3

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Education 3

  1. Kyoto University   Graduate School, Division of Natural Science

    1995.4 - 1998.3

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    Country： Japan

  2. Kyoto University   Graduate School, Division of Natural Science

    1993.4 - 1995.3

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    Country： Japan

  3. Kyoto University   Faculty of Science

    1989.4 - 1993.3

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    Country： Japan

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Professional Memberships 3

  1. American Geophysical Union

  2. Society of Geomagnetism and Earth, Planetary and Space Sciences

  3. American Geophysical Union

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Awards 1

  1. National research council resident research associateship award

    1998.5   National research council  

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Papers 55

  1. Curved Trajectory Effect on Charge-Exchange Collision at Ionospheric Temperatures Reviewed

    Ieda, A.

    Journal of Geophysical Research: Space Physics     2022.1

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    Collision between ions and neutral particles is an essential characteristic of Earth's ionosphere. This ion-neutral collision is usually caused by the polarization of neutral particles. This collision can also be caused by charge exchange, if the particle pair is parental, such as atomic oxygen and its ion. The total collision frequency is not the sum of the polarization and charge-exchange components, but is essentially equal to the dominant component. The total is enhanced only around the classic transition temperature, which is near the ionospheric temperature range (typically 200–2000 K). However, the magnitude of this enhancement has differed among previous studies; the maximum enhancement has been reported as 41% and 11% without physical explanation. In the present study, the contribution of the polarization force to the charge-exchange collision is expressed as a simple curved particle trajectory effect. As a result, the maximum enhancement is found to be 22%. It is discussed that the enhancement has been neglected in classic ionospheric studies partly due to confusion with the glancing particle contribution, which adds 10.5% to the polarization component. The enhancement has been neglected presumably also because there has been no functional form to express it. Such an expression is derived in this study.

    DOI： 10.1029/2020JA028441

    DOI： 10.1029/2020JA028441

  2. Atomic Oxygen Ion‐Neutral Collision Frequency Models at Ionospheric Temperatures Reviewed

    Ieda, A.

    Journal of Geophysical Research: Space Physics     2021.1

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2021JA029612

    DOI： 10.1029/2021JA029612

  3. Location and Timing of Magnetic Reconnections in Earth's Magnetotail: Accomplishments of the 29-Year Geotail Near- Earth Magnetotail Survey Reviewed International coauthorship

    Nagai, T., Shinohara, I., Saito, Y., Ieda, A., & Nakamura, R.

    Journal of Geophysical Research: Space Physics   Vol. 128   2023.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2023JA032023

    DOI： 10.1029/2023JA032023

  4. Ion-neutral collision frequencies for calculating ionospheric conductivity Reviewed

    Ieda, A.

    Journal of Geophysical Research: Space Physics   Vol. 125 ( 2 )   2020.2

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2019JA027128

    Web of Science

  5. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images Reviewed

    Ieda Akimasa, Kauristie Kirsti, Nishimura Yukitoshi, Miyashita Yukinaga, Frey Harald U., Juusola Liisa, Whiter Daniel, Nose Masahito, Fillingim Matthew O., Honary Farideh, Rogers Neil C., Miyoshi Yoshizumi, Miura Tsubasa, Kawashima Takahiro, Machida Shinobu

    EARTH PLANETS AND SPACE   Vol. 70   2018.5

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1186/s40623-018-0843-3

    Web of Science

  6. Stepwise tailward retreat of magnetic reconnection: THEMIS observations Reviewed

    Ieda, A. , Y. Nishimura, Y. Miyashita, V. Angelopoulos, A. Runov, T. Nagai, H. U. Frey, D. H. Fairfield, J. A. Slavin, H. Vanhämaki, H. Uchino, R. Fujii, Y. Miyoshi, and S. Machida

    J. Geophys. Res. Space Physics   Vol. 121   page： 4548-4568   2016.5

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    Auroral stepwise poleward expansions were clarified by investigating a multiple-onset substorm that occurred on 27 February 2009. Five successive auroral brightenings were identified in all-sky images, occurring at approximately 10 min intervals. The first brightening was a faint precursor. The second brightening had a wide longitude; thus, it represented the Akasofu substorm onset. Other brightenings expanded poleward; thus, they were interpreted to be auroral breakups. These breakups occurred stepwise; that is, later breakups were initiated at higher latitudes. Corresponding reconnection signatures were studied using Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite observations from between 8 and 24 Re down the magnetotail. The Akasofu substorm onset was not accompanied by a clear reconnection signature in the tail. In contrast, the three subsequent auroral breakups occurred simultaneously (within a few min) with three successive fast flows at 24 Re; thus, these were interpreted to be associated with impulsive reconnection episodes. These three fast flows consisted of a tailward flow and two subsequent earthward flows. The flow reversal at the second breakup indicated that a tailward retreat of the near-Earth reconnection site occurred during the substorm expansion phase. In addition, the earthward flow at the third breakup was consistent with the classic tailward retreat near the end of the expansion phase; therefore, the tailward retreat is likely to have occurred in a stepwise manner. We interpreted the stepwise characteristics of the tailward retreat and poleward expansion to be potentially associated by a stepwise magnetic flux pile-up.

    DOI： 10.1002/2015JA022244

  7. Approximate forms of daytime ionospheric conductance Reviewed

    Ieda, A., S. Oyama, H. Vanhamäki, R. Fujii, A. Nakamizo, O. Amm, T. Hori, M. Takeda, G. Ueno, A. Yoshikawa, R. J. Redmon, W. F. Denig, Y. Kamide, and N. Nishitani

    J. Geophys. Res.   Vol. 119   2014.11

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    The solar zenith angle (SZA) dependence of the conductance is studied and a simple theoretical form for the Hall-to-Pedersen conductance ratio is developed, using the peak plasma production height. The European Incoherent Scatter (EISCAT) radar observations at Tromso (67 MLAT) on 30 March 2012 were used to calculate the conductance. The daytime electric conductance is associated with plasma created by solar extreme ultraviolet radiation incident on the neutral atmosphere of the Earth. However, it has been uncertain whether previous conductance models are consistent with the ideal Chapman theory for such plasma productions. We found that the SZA dependence of the conductance is consistent with the Chapman theory after simple modifications. The Pedersen conductance can be understood by approximating the plasma density height profile as being flat in the topside E region, and by taking into account the upward gradient of atmospheric temperature. An additional consideration is necessary for the Hall conductance, which decreases with increasing SZA more rapidly than the Pedersen conductance. This rapid decrease is presumably caused by a thinning of the Hall conductivity layer from noon towards nighttime. We expressed this thinning in terms of the peak production height in the Chapman theory.

    DOI： 10.1002/2014JA020665

  8. A Statistical Study of Near-Earth Magnetotail Evolution During Pseudosubstorms and Substorms With THEMIS Data

    Fukui Kento, Miyashita Yukinaga, Machida Shinobu, Miyoshi Yoshizumi, Ieda Akimasa, Nishimura Yukitoshi, Angelopoulos Vassilis

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   Vol. 125 ( 1 )   2020.1

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  9. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images (vol 70, 73, 2018)

    Ieda Akimasa, Kauristie Kirsti, Nishimura Yukitoshi, Miyashita Yukinaga, Frey Harald U., Juusola Liisa, Whiter Daniel, Nose Masahito, Fillingim Matthew O., Honary Farideh, Rogers Neil C., Miyoshi Yoshizumi, Miura Tsubasa, Kawashima Takahiro, Machida Shinobu

    EARTH PLANETS AND SPACE   Vol. 71   2019.7

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  10. Revisiting substorm events with preonset aurora

    Miyashita Yukinaga, Ieda Akimasa

    ANNALES GEOPHYSICAE   Vol. 36 ( 5 ) page： 1419-1438   2018.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.5194/angeo-36-1419-2018

    Web of Science

  11. Theory, modeling, and integrated studies in the Arase (ERG) project

    Seki Kanako, Miyoshi Yoshizumi, Ebihara Yusuke, Katoh Yuto, Amano Takanobu, Saito Shinji, Shoji Masafumi, Nakamizo Aoi, Keika Kunihiro, Hori Tomoaki, Nakano Shin'ya, Watanabe Shigeto, Kamiya Kei, Takahashi Naoko, Omura Yoshiharu, Nose Masahito, Fok Mei-Ching, Tanaka Takashi, Ieda Akimasa, Yoshikawa Akimasa

    EARTH PLANETS AND SPACE   Vol. 70   2018.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1186/s40623-018-0785-9

    Web of Science

  12. Visualization tool for three-dimensional plasma velocity distributions (ISEE_3D) as a plug-in for SPEDAS

    Keika Kunihiro, Miyoshi Yoshizumi, Machida Shinobu, Ieda Akimasa, Seki Kanako, Hori Tomoaki, Miyashita Yukinaga, Shoji Masafumi, Shinohara Iku, Angelopoulos Vassilis, Lewis Jim W., Flores Aaron

    EARTH PLANETS AND SPACE   Vol. 69   2017.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1186/s40623-017-0761-9

    Web of Science

  13. A direct link between chorus emissions and pulsating aurora on timescales from milliseconds to minutes: A case study at subauroral latitudes Reviewed

    Ozaki, M., S. Yagitani, K. Sawai, K. Shiokawa, Y. Miyoshi, R. Kataoka, A. Ieda, Y. Ebihara, M. Connors, I. Schofield

    J. Geophys. Res. Space Physics   Vol. 120   page： 9617-9631   2015.11

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    DOI： 10.1002/2015JA021381

  14. Statistical visualization of the Earth's magnetotail and the implied mechanism of substorm triggering based on superposed-epoch analysis of THEMIS data Reviewed

    Machida, S., Y. Miyashita, A. Ieda, M. Nosé, V. Angelopoulos, and J. P. McFadden

    Ann. Geophys.   Vol. 32   page： 99–111   2014.2

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.5194/angeo-32-99-2014

  15. Ground-based ELF/VLF chorus observations at subauroral latitudes - VLF-CHAIN Campaign Reviewed

    Shiokawa, K., Y. Yokoyama, A. Ieda, Y. Miyoshi, R. Nomura, S. Lee, N. Sunagawa, Y. Miyashita, M. Ozaki, K. Ishizaka, S. Yagitani, R. Kataoka, F. Tsuchiya, I. Schofield, and M. Connors

    J. Geophys. Res.   Vol. 119   2014

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2014JA020161

  16. General solution for calculating polarization electric fields in the auroral ionosphere and application examples Reviewed

    Amm, O., R. Fujii, H. Vanhamäki, A. Yoshikawa, and A. Ieda

    J. Geophys. Res.   Vol. 118   page： A11217   2013.5

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： doi:10.1002/jgra.50254

  17. An application of the finite length Cowling channel model to auroral arcs with longitudinal variations Reviewed

    Fujii, R., O. Amm, H. Vanhamäki, A. Yoshikawa, and A. Ieda

    J. Geophys. Res.   Vol. 117   page： A11217   2012.11

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： doi:10.1029/2012JA017953

  18. Observed correlation between pulsating aurora and chorus waves at Syowa Station in Antarctica Reviewed

    Ozaki, M., S. Yagitani, K. Ishizaka, K. Shiokawa, Y. Miyoshi, A. Kadokura, H. Yamagishi, R. Kataoka, A. Ieda, Y. Ebihara, N. Sato, and I. Nagano

    J. Geophys. Res.   Vol. 117   page： A08211   2012

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： A08211, doi:10.1029/2011JA017478

  19. Rayleigh-Taylor type instability in auroral patches Reviewed

    Shiokawa, K., A. Nakajima, A. Ieda, K. Sakaguchi, R. Nomura, T. Aslaksen,M. Greffen, and E. Donovan

    J. Geophys. Res.   Vol. 115   page： A02211, doi:10.1029/2009JA014273   2010.2

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  20. A statistical investigation of the Cowling channel efficiency in the auroral zone Reviewed

    Amm, O., R. Fujii, K. Kauristie, A. Aikio, A. Yoshikawa, A. Ieda, and H. Vanhamäki

    J. Geophys. Res.   Vol. 116   page： A02304, doi:10.1029/2010JA015988   2010

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  21. Reformulation and energy flow of the Cowling channel Reviewed

    Fujii, R., O. Amm, A. Yoshikawa, A. Ieda, and H. Vanhamäki

    J. Geophys. Res.   Vol. 116   page： A02305, doi:10.1029/2010JA015989   2010

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  22. Pressure changes associated with substorm depolarization in the near-Earth plasma sheet Reviewed

    Y. Miyashita, S. Machida, A. Ieda, D. Nagata, Y. Kamide, M. Nosé, K. Liou, T. Mukai, S. P. Christon, C. T. Russell, I. Shinohara, and Y. Saito

    J. Geophys. Res.   Vol. 115   page： A12239, doi:10.1029/2010JA015608   2010

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  23. Optical and particle observations of type B red aurora Reviewed

    Ebihara, Y., T. Sakanoi, K. Asamura, M. Hirahara, and A. Ieda

    Geophys. Res. Lett.   Vol. 36   page： L20105, doi:10.1029/2009GL041037   2009.10

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  24. Geotail observations of plasma sheet ion composition over 16 years: On variations of average plasma ion mass and O+ triggering substorm model Reviewed

    Nose, M., A. Ieda, and S. P. Christon

    J. Geophys. Res.   Vol. 114   page： A07223, doi:10.1029/2009JA014203   2009.7

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  25. Statistical visualization of the Earth's magnetotail based on Geotail data and the implied substorm model Reviewed

    Machida, S., Y. Miyashita, A. Ieda, M. Nosé, D. Nagata, K. Liou, T. Obara, A. Nishida, Y. Saito, and T. Mukai

    Ann. Geophys.   Vol. 27   page： 1035-1046   2009

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  26. Longitudinal development of a substorm brightening arc Reviewed

    Shiokawa, K., A. Ieda, A. Nakajima, K. Sakaguchi, R. Nomura, T. Aslaksen, M. Greffen, E. Spanswick, E. Donovan, S. B. Mende, J. McFadden, K.-H. Glassmeier, V. Angelopoulos, and Y. Miyashita

    Ann. Geophys.   Vol. 27 ( 5 ) page： 1935-1940   2009

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  27. Mapping of ionospheric parameters for space weather predictions: A concise review

    Y. Kamide, A. Ieda

    SCIENCE IN CHINA SERIES E-TECHNOLOGICAL SCIENCES   Vol. 51 ( 10 ) page： 1589 - 1599   2008.10

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    Language：English   Publisher：SCIENCE PRESS  

    Reviewing briefly the recent progress in a joint program of specifying the polar ionosphere primarily on the basis of ground magnetometer data, this paper emphasizes the importance of processing data from around the world in real time for space weather predictions. The output parameters from the program include ionospheric electric fields and currents and field-aligned currents. These real-time records are essential for running computer simulations under realistic boundary conditions and thus for making numerical predictions of space weather efficient as reliable as possible. Data from individual ground magnetometers as well as from the solar wind are collected and are used as input for the KRM and AMIE magnetogram-inversion algorithms, through which the two-dimensional distribution of the ionospheric parameters is calculated. One of the goals of the program is to specify the solar-terrestrial environment in terms of ionospheric processes and to provide the scientific community with more than what geomagnetic activity indices and statistical models indicate.

    DOI： 10.1007/s11431-008-0254-y

    Web of Science

  28. Longitudinal association between magnetotail reconnection and auroral breakup based on Geotail and Polar observations Reviewed

    A. Ieda, D. H. Fairfield, J. A. Slavin, K. Liou, C. -I. Meng, S. Machida, Y. Miyashita, T. Mukai, Y. Saito, M. Nose, J. -H. Shue, G. K. Parks, M. O. Fillingim

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   Vol. 113 ( A8 ) page： A08207, 10.1029/2008JA013127   2008.8

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

    The dawn-dusk locations of reconnection in the near-earth magnetotail at the time of isolated auroral breakup are studied to clarify whether breakup is always accompanied by reconnection. The near-earth reconnection is identified by tailward plasma flows faster than 200 km/s with southward magnetic field. We first identified 66 breakups in the Polar ultraviolet imager observations of the nightside polar ionosphere. We then studied tailward flows during breakups using Geotail in situ observations of the plasma sheet between 25 and 31 RE down the tail. It was found that the dawn-dusk (Y) locations of relatively fast (>= 400 km/s) tailward flows were associated with breakup magnetic local time (MLT) by a regression line of YAGSM = -5.7 x (MLT + 0.6) R(E) with a correlation coefficient of 0.8. Most tailward flows were observed within 5 R(E) of the modeled Y locations, where tailward flows occurred in 88% of the 26 cases of breakups between 22 and 0 MLT. It is thus inferred that in most cases, breakup is accompanied by tailward flow near the breakup MLT with its dawn-dusk dimension similar to 10 R(E). There were only two events without tailward flows in the region where flows have been expected. These two events were an earthward flow event and a traveling compression region event, which are not inconsistent with the initiation of the near-earth reconnection. Auroral breakup is thus likely to always be accompanied by near-earth reconnection near breakup MLT. It is also inferred that reconnection and breakup occur simultaneously within a few minutes, assuming a time delay between reconnection onset and the arrival of tailward flows at satellite locations.

    DOI： 10.1029/2008JA013127

    Web of Science

  29. *Longitudinal association between magnetotail reconnection and auroral breakup based on Geotail and Polar observations Reviewed

    Ieda, A., D. H. Fairfield, J. A. Slavin, K. Liou, C.-I. Meng, S. Machida, Y. Miyashita, T. Mukai, Y. Saito, M. Nosé, J.-H. Shue, G. K. Parks, and M. O. Fillingim

    J. Geophys. Res.   Vol. 113 ( A8 ) page： A08207, 10.1029/2008JA013127   2008.8

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  30. *Two classes of earthward fast flows in the plasma sheet Reviewed

    J.-H. Shue, A. Ieda, A. T. Y. Lui, G. K. Parks, T. Mukai, and S. Ohtani

    J. Geophys. Res.   Vol. 113 ( A2 ) page： A002205, doi:10.1029/2007JA012456   2008.2

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  31. Mapping of ionospheric parameters for space weather predictions: A concise review Invited Reviewed

    Kamide Y., and A. Ieda

    Sci. China Ser. E-Tech. Sci.   Vol. 51 ( 10 ) page： 1589-1599, doi:10.1007/s11431-008-0254-y   2008

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  32. Towards understanding the electrodynamics of the 3-dimensional high-latitude ionosphere: present and future, Reviewed

    Amm, O., A. Aruliah, S. C. Buchert, R. Fujii, J.W. Gjerloev, A. Ieda, T. Matsuo, C. Stolle, H. Vanham¨aki, and A. Yoshikawa

    Ann. Geophys.   Vol. 26   page： 3913–3932   2008

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  33. Simultaneous ground and satellite observations of an isolated proton arc at subauroral latitudes Reviewed

    Sakaguchi, K., K. Shiokawa, A. Ieda, Y. Miyoshi, Y. Otsuka, T. Ogawa, M. Connors, E. F. Dononvan, and F. J. Rich

    J. Geophys. Res   Vol. 112   page： A04202, doi:10.1029/2006JA012135   2007

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  34. ERG - A small-satellite mission to investigate the dynamics of the inner magnetosphere Reviewed

    Shiokawa, K., K. Seki, Y. Miyoshi, A. Ieda, T. Ono, M. Iizima, T. Nagatsuma, T. Obara, T. Takashima, K. Asamura, Y. Kasaba, A. Matsuoka, Y. Saito, H. Saito, M. Hirahara, Y. Tonegawa, F. Toyama, M. Tanaka, M. Nose, Y. Kasahara, K. Yumoto, H. Kawano, A. Yoshikawa, Y. Ebihara, A. Yukimatsu, N. Sato, S. Watanabe, and the Inner Magnetosphere Subgroup in the Society of Geomagnetism and Earth, Planetary and Space Sciences

    Adv. Space Res.   Vol. 38 ( 8 ) page： 1861-1869   2006

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  35. Real-time modeling of the ionosphere using GEDAS/KRM for space weather

    Ieda, A. and Y. Kamide

    Proceedings of The 7th International School/Symposium for Space Simulations     page： 259-260   2005

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    Authorship：Lead author   Language：English   Publishing type：Research paper (bulletin of university, research institution)  

  36. Plasmoids observed in the near-Earth magnetotail at X~-7 Re Reviewed

    J. Geophys. Res   Vol. 110   page： A12214, doi:10.1029/2005JA011263   2005

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  37. Solar wind control of the radial distance of the magnetic reconnection site in the magnetotail Reviewed

    Nagai T., M. Fujimoto, R. Nakamura, W. Baumjohann, A. Ieda, I. Shinohara, S. Machida, Y. Saito, and T. Mukai

    J. Geophys. Res   Vol. 110   page： A09208, doi:10.1029/2005JA011207   2005

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  38. Geotail observations of signatures in the near-Earth magnetotail for the extremely intense substorms of the 30 October 2003 storm Reviewed

    Miyashita Y., Y. Miyoshi, Y. Matsumoto, A. Ieda, Y. Kamide, M. Nosé, S. Machida, H. Hayakawa, R. W. McEntire, S. P. Christon, D. S. Evans, and O. A. Troshichev

    J. Geophys. Res   Vol. 110   page： A09S25, doi:10.1029/2005JA011070   2005

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  39. Magnetotail response to prolonged southward IMF Bz intervals: Loading, unloading, and continuous magnetospheric dissipation Reviewed

    Tanskanen, E. I., J. A Slavin, D. H. Fairfield, D. G Sibeck, J. Gjerloev, T. Mukai, A. Ieda, and T. Nagai

    J. Geophys. Res   Vol. 110   page： A03216, doi: 10.1029/2004JA010561   2005

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  40. Difference between earthward and tailward flows in their dependences on geomagnetic and IMF conditions Reviewed

    A Ieda, T Mukai, S Machida, JH Shue, SI Ohtani, T Nagai, Y Saito

    Frontiers in Magnetospheric Plasma Physics: Celebrating 10 Years of Geotail Operation   Vol. 16   page： 186 - 189   2005

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

    Earthward and tailward perpendicular fast flows in the plasma sheet were studied and their differences in response to geomagnetic conditions and to interplanetary magnetic field (IMF) conditions are discussed. We first identified the plasma sheet from 3.5 years of Geotail plasma and magnetic filed observations between 8 and 32 R-E down the tail. We then studied occurrence rates of fast flows during geomagnetically quiet and active intervals as identified by Kp and ASY indices, and during northward and southward IMF intervals. As a result, both earthward and tailward flows were observed more often during active or southward IMF intervals than during quiet or northward IMF intervals, as expected. On the other hand, we found that there is a difference between earthward and tailward flows: Dependences on geomagnetic conditions are more evident in tailward flows than in earthward flows. We further discuss that tailward flows indicate the substorm expansion phase better than earthward flows do.

    Web of Science

  41. Roles of the magnetic reconnection in the Earth's magnetotail during substorms: Geotail observations Invited Reviewed

    Machida, S., A. Ieda, and Y. Miyashita

    Physics of Magnetic Reconnection in High-Temperature Plasmas, edited by M. Ugai, Research Signpost, Kerala, India     page： 161-191   2004

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  42. Difference between earthward and tailward flows in their dependences on geomagnetic and IMF conditions Reviewed

    Ieda, A., T. Mukai, S. Machida, J.-H. Shue, S.-I. Ohtani, T. Nagai, and Y. Saito

    COSPAR Colloquia Series   Vol. 16   page： 186-189   2004

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  43. Difference in magnetotail variations between intense and weak substorms Reviewed

    Miyashita Y., Y. Kamide, S. Machida, K. Liou, T. Mukai, Y. Saito, A. Ieda, C.-I. Meng, and G. K. Parks

    J. Geophys. Res   Vol. 109   page： doi:10.1029/2004JA010588   2004

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    Language：English   Publishing type：Research paper (scientific journal)  

  44. Quiet time magnetotail plasma flow: Coordinated Polar ultraviolet images and Geotail observations Reviewed

    A Ieda, JH Shue, K Liou, SI Ohtani, CI Meng, DH Fairfield, T Mukai, Y Saito, S Machida, T Nagai, GK Parks

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   Vol. 108 ( A9 ) page： 10.1029/2002JA009739   2003.9

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

    [ 1] A search for fast flows in the plasma sheet during quiet times was conducted in order to further test the previously found close association between fast flows and auroral brightenings. We first identified "quiet intervals'' of at least 30-min duration in the Polar ultraviolet global images of auroras. During 16 months of Polar observations from January 1997 through April 1998, 41 quiet intervals were identified when Geotail was between 8 and 31 RE down the tail and within 10 RE of the midnight meridian. Fast flows were more rare during the quiet intervals than at other times. For 4 of the 41 intervals identified, Geotail detected flows faster than 300 km s(-1) in the plasma sheet. All the four flows were earthward parallel flows accompanied by northward magnetic field beyond 20 RE, and there were no perpendicular flows faster than 300 km s(-1). To understand the nature of the fast ( but not perpendicular) flows during the quiet intervals, an earthward flow at 21 RE down the tail was studied in detail. The plasma beta was higher than unity during the earthward flow, but the fastest ion velocity moments consisted of the two counterstreaming components flowing along the magnetic field, a characteristic known to define the plasma sheet boundary layer. Our results further support the close association between auroral brightenings and clear fast flows as seen in previous studies, because no perpendicular fast flows were found during quiet intervals. Since some perpendicular flows slower than 300 km s(-1) were found beyond -20 R-E down the tail, a velocity of -300 km s(-1) appears to statistically make a difference in the geoeffectiveness of perpendicular flows.

    DOI： 10.1029/2002JA009739

    Web of Science

  45. Geotail observations of magnetic flux ropes in the plasm a sheet, Reviewed

    Slavin, J.A., R.P. Lepping, J. Gjerloev, D.H. Fairfield, M. H esse, C.J. Owen, M.B. Moldwin, T. Nagai, A. Ieda, and T. Mukai

    J. Geophys. Res   Vol. 108   page： 10.1029/2002JA009557   2003

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    Language：English   Publishing type：Research paper (scientific journal)  

  46. *Quiet time magnetotail plasma flow: Coordinated Polar ultraviolet images and Geotail observations Reviewed

    Ieda, A., J.-H. Shue, K. Liou, S.-I. Ohtani, C.-I. Meng, D.H. Fairfield, T. Mukai, Y. Saito, S. Machida, T. Nagai, and G.K. Parks

    J. Geophys. Res.   Vol. 108   page： 10.1029/2002JA009739   2003

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  47. Quantitative relationships between rlasma sheet fast flows and nightside auroral power Reviewed

    J.-H. Shue, S. Ohtani, P.T. Newell, K. Liou, C.-I. Meng, A. Ieda, and T. Mukai

    J. Geophys. Res   Vol. 108   page： 10.1029/2002JA009794   2003

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    Language：English   Publishing type：Research paper (scientific journal)  

  48. Simultaneous observations of earthward flow burst and plasmoid ejection during magnetospheric substorms Reviewed

    Slavin, J.A., D.H. Fairfield, R.P. Lepping, M. Hesse, A. Ieda, E. Tanskanen, N. Ostgaard, T. Mukai, T. Nagai, H.J. Singer, and P.R. Sutcliffe

    J. Geophys. Res   Vol. 107   page： 10.1029/2000JA003501   2002

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    Language：English   Publishing type：Research paper (scientific journal)  

  49. Magnetospheric signature of an ionospheric traveling convection vortex event Reviewed

    Moretto, T., M. Hesse, A. Yahnin, A. Ieda, D. Man, and J.F. Waternann

    J. Geophys. Res   Vol. 107   page： 10.1029/2001JA000049   2002

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  50. Plasmoid ejection and auroral brightenings Reviewed

    A Ieda, DH Fairfield, T Mukai, Y Saito, S Kokubun, K Liou, CI Meng, GK Parks, MJ Brittnacher

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   Vol. 106 ( A3 ) page： 3845 - 3857   2001.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

    Geotail plasma and magnetic field observations of 24 plasmoids between 21 and 29 R-E have been compared with Polar ultraviolet observations of auroral brightenings. Both single and multiple plasmoids almost always corresponded to brightenings, but the brightenings were sometimes weak and spatially limited and did not always grow to a global substorm. Even a case where a plasmoid event occurred with fast postplasmoid flow corresponded to a weak brightening but no substorm. Some brightenings did not correspond to plasmoids, but these brightenings were observed away from the longitude of Geotail, indicating that plasmoids have a small longitudinal extent in the near tail. The plasmoids were occasionally observed before the brightenings but more frequently were observed 0-2 min after the brightenings with the delays probably due to the transit time to the observation point. It seems likely that; formation of a near-Earth neutral line causes each brightening in the polar ionosphere. but these formations do not always lead to a full-fledged substorm. What additional circumstance causes development of a full, large-scale substorm remains an open question.

    Web of Science

  51. *Plasmoid ejection and auroral brightenings Reviewed

    Ieda, A., D.H. Fairfield, T. Mukai, Y. Saito, S. Kokubun, K. Liou, C.-I. Meng, G.K. Parks, and M.J. Brittnacher

    J. Geophys. Res.   Vol. 106   page： 3845-3857   2001

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  52. Statistical visualization of Earth's magnetotail during substorms by means of multidimensional superposed epoch analysis with Geotail data Reviewed

    Machida, S., A. Ieda, T. Mukai, Y. Saito, and A. Nishida

    J. Geophys. Res.   Vol. 105   page： 25,291-25,303   2000

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  53. GEOTAIL observations of flow velocity and north-south magnetic field variations in the near and mid-distant tail associated with substorm onsets Reviewed

    Machida, S., Y. Miyashita, A. Ieda, A. Nishida, T. Mukai, Y. Saito, and S. Kokubun,

    Geophys. Res. Lett   Vol. 26   page： 635-638   1999

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  54. Statistical analysis of the plasmoid evolution with Geotail observations Reviewed

    A Ieda, S Machida, T Mukai, Y Saito, T Yamamoto, A Nishida, T Terasawa, S Kokubun

    JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS   Vol. 103 ( A3 ) page： 4453 - 4465   1998.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

    Plasmoids in the Earth's magnetotail were studied statistically, using low energy particle (LEP) and magnetic field (MGF) data from the Geotail spacecraft. Their evolution along the tail axis from X(GSM') = -16 to -210 R(E) was investigated with 824 plasmoid events. Their dependence on Y(GSM') was studied as well to derive the three-dimensional structure of the plasmoids. (The coordinates are aberrated to remove the average effects of the orbital velocity of the Earth about the Sun.) We defined a plasmoid as a structure with rotating magnetic fields and enhanced total pressure. In the near tail (X(GSM') greater than or equal to -50 R(E)), there was a tendency for the plasmoids to be observed in the premidnight sector around the tail axis (\Y(GSM') - 3\ less than or equal to 10 R(E)), while they were observed widely (\Y(GSM')\ less than or equal to 20 R(E)) in the middle tail (-50 > X(GSM') greater than or equal to -100 R(E)) and in the distant tail (-100 R(E) > X(GSM')). The plasmoids expanded in the +/-Y(GSM') direction with typical velocities of +/-130 +/- 100 km/s in the near tail. This strongly supports the view that plasmoids are initially formed at the near-Earth neutral line which has a limited extent in the Y(GSM') direction. The plasmoids accelerated in the downtail direction from 400 +/- 200 km/s to 700 +/- 300 km/s from the near to the middle tail. Then, it is suggested that they decelerated to 600 +/- 200 km/s as they traveled to the distant tail. The ion temperature inside plasmoids was 4.5 +/- 2 keV in the near and middle tail, and then rapidly decreased to 2 +/- 1 keV from the middle to the distant tail region. The ion temperature in the distant tail was 2 times higher than the values deduced previously. Typical plasmoid dimensions were estimated to be 10 R(E) (length) x 40 R(E) (width) x 10 R(E) (height) in the middle and distant tail. The energy carried by each plasmoid was similar to 2 x 10(14) J in the middle tail, half of which was lost from the middle to the distant tail. Inside plasmoids,the thermal energy flux exceeded the bulk energy flux and Poynting flux. The energy released tailward in the course of a substorm was estimated to be roughly 10(15) J.

    DOI： 10.1029/97JA03240

    Web of Science

  55. *Statistical analysis of the plasmoid evolution with Geotail observations Reviewed

    Ieda, A., S. Machida, T. Mukai, Y. Saito, T. Yamamoto, A. Nishida, T. Terasawa, and S. Kokubun

    J. Geophys. Res.   Vol. 103   page： 4453-4465   1998

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MISC 4

  1. MMS衛星群とGeotail衛星によるサブストーム開始の同時観測

    家田章正, 北村成寿, 齋藤義文, 横田勝一郎, POLLOCK Craig J., GILES Barbara L., RUSSELL C.T., 町田忍, 長井嗣信, 熊本篤志, 土屋史紀, 笠原禎也, 三好由純

    地球電磁気・地球惑星圏学会総会及び講演会(Web)   Vol. 144th   2018

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  2. 電離圏電気伝導度の太陽天頂角依存性

    家田章正, 大山伸一郎, 藤井良一, 中溝葵

    地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)   Vol. 134th   2013

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  3. FAST衛星によるオーロラサージ電流系の観測

    家田章正, 藤本正樹, 西野真木, 堀智昭, 関華奈子, MCFADDEN James P., 西村幸敏, 藤井良一, 海老原祐輔, 町田忍, 宮下幸長, 齋藤義文

    地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)   Vol. 128th   2010

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  4. Real-time modeling of the ionosphere using GEDAS/KRM for space weather

    Ieda, A, Y. Kamide

    Proceedings of The 7th International School/Symposium for Space Simulations     page： 259-260   2005

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    Language：English   Publishing type：Rapid communication, short report, research note, etc. (bulletin of university, research institution)  

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Presentations 12

  1. 尾部リコネクション領域の移動：THEMIS地上・衛星観測

    家田章正

    磁気圏ダイナミクス研究会 

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    Event date： 2018.3

    Language：English   Presentation type：Oral presentation (general)  

    Venue：名古屋大学, 名古屋   Country：Japan  

  2. オーロラキロメートル放射とオーロラ極方向拡大との関係：Geotail衛星と地上全天観測 International conference

    家田章正, 宮下幸長, 町田忍, 三浦翼, 川嶋貴大

    , 地球電磁気・地球惑星圏学会（第142回総会・講演会）, 

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    Event date： 2017.10

    Language：English   Presentation type：Oral presentation (general)  

    Venue：京都大学, 宇治   Country：Japan  

  3. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images Invited International conference

    The 13th International Conference on Substorms 

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    Event date： 2017.9

    Language：English   Presentation type：Oral presentation (invited, special)  

    Venue：Sheraton Portsmouth Harborside Hotel, Portsmouth, NH, USA   Country：Japan  

  4. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images International conference

    19. Ieda, A., S. Machida, Y. Miyoshi, T. Kawashima, T. Miura, K. Kauristie, Y. Nishimura, Y. Miyashita, G. K. Parks, and M. O. Fillingim

    地球惑星科学連合2017年大会 

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    Event date： 2017.5

    Language：English   Presentation type：Oral presentation (general)  

    Venue：幕張メッセ, 幕張   Country：Japan  

  5. 電離圏電気伝導度を算出するための衝突周波数

    家田章正

    地球電磁気・地球惑星圏学会  2019.10.26 

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    Language：Japanese  

  6. 電離圏F領域の衝突周波数モデル

    家田章正

    地球電磁気・地球惑星圏学会  2020.11.3 

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    Language：Japanese   Presentation type：Oral presentation (general)  

  7. 尾部リコネクション領域の移動：THEMIS地上・衛星観測 International conference

    家田章正

    磁気圏ダイナミクス研究会  2018.3.19 

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    Language：English   Presentation type：Oral presentation (general)  

    Venue：名古屋大学, 名古屋  

  8. オーロラキロメートル放射とオーロラ極方向拡大との関係：Geotail衛星と地上全天観測

    家田章正, 宮下幸長, 町田忍, 三浦翼, 川嶋貴大

    , 地球電磁気・地球惑星圏学会（第142回総会・講演会）,  2017.10.19 

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    Language：English   Presentation type：Oral presentation (general)  

    Venue：京都大学, 宇治  

  9. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images

    Ieda, A, S. Machida, Y. Miyoshi, T. Kawashima, T. Miura, K. Kauristie, Y. Nishimura, Y. Miyashita, G. K. Parks, M. O. Fillingim

    地球惑星科学連合2017年大会  2017.5.21 

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    Language：English   Presentation type：Oral presentation (general)  

    Venue：幕張メッセ, 幕張  

  10. Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images Invited

    Ieda, A, K. Kauristie, L. Juusola, Y. Nishimura, Y. Miyashita, D. H. Fairfield, H. U. Frey, M. O. Fillingim, D. Whiter, F. Honary, N. C. Rogers, Y. Miyoshi, S. Machida

    The 13th International Conference on Substorms  2017.9.26 

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    Language：English   Presentation type：Oral presentation (invited, special)  

    Venue：Sheraton Portsmouth Harborside Hotel, Portsmouth, NH, USA  

  11. MMS衛星群とGeotail衛星によるサブストーム開始の同時観測

    家田章正, 北村成寿, 齋藤義文, 横田勝一郎, C. J. Pollock, B. L. Giles, C. T. Russell, R. Nakamura, 町田忍, 長井嗣信, 熊本篤志, 土屋史紀, 笠原禎也, 三好由純, 松岡彩子

    地球電磁気・地球惑星圏学会  2018.11.27 

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    Language：Japanese   Presentation type：Oral presentation (general)  

  12. Auroral substorm onset in satellite-based global images and ground-based all-sky images

    A. Ieda, K. Kauristie, L. Juusola, Y. Nishimura, Y. Miyashita, H. U. Frey, M. O. Fillingim, D. Whiter, M Nosé, Y. Miyoshi, S. Machida, F. Honary, N. C. Rogers

    Japan Geoscience Union 2019  2019.5.29 

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    Language：English   Presentation type：Poster presentation  

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KAKENHI (Grants-in-Aid for Scientific Research) 17

  1. Auroral current system as estimated by a magnetic inversion method

    Grant number：20540438  2008 - 2011

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    IEDA Akimasa

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    Authorship：Principal investigator 

    Grant amount：\4420000 （ Direct Cost: \3400000 、 Indirect Cost：\1020000 ）

    The spatial distribution of field-aligned currents(FACs) is studied for an intense substorm. We first estimated the height-integrated ionospheric Hall and Pedersen conductances from ultraviolet images taken by the Polar satellite. To derive FACs, we then employed Ohm's law for the ionosphere, applying a magnetic inversion method to the input conductances and ground magnetic field data. As a result, the Hall FACs that are connected to the ionospheric Hall currents were aniti-correlated with the Pedersen FACs that are connected to the ionospheric Pedersen currents. Such anti-correlations were observed near the poleward and the equatorward edges of the auroral westward currents. This result indicates that the auroral current system included the Cowling channel that is the auroral westward currents enhanced by the polarization electric field in this particular event.

  2. 衛星観測と地磁気逆計算法によるオーロラ爆発開始条件の解明

    Grant number：17740325  2005 - 2007

    科学研究費助成事業  若手研究(B)

    家田 章正

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    Authorship：Principal investigator 

    Grant amount：\3600000 （ Direct Cost: \3600000 ）

    地球の電離圏では数時間に一度、オーロラが爆発的に発達する。本研究の目的は、オーロラ爆発が開始するために必要な条件を明らかにすることである。特に、オーロラ爆発時における、磁気圏近尾部リコネクションの、朝夕方向の位置を調べることにより、オーロラ爆発時にはリコネクションが必ず生じているのかどうかを明らかにした。近尾部リコネクションは南向き磁場を伴う200km/s以上の反地球向き高速流により同定した。まず、66例の孤立したオーロラ爆発を、ポーラー衛星の紫外線オーロラ観測により同定した。次に、オーロラ爆発時に、地球から反太陽方向に5-31地球半径、かつ朝夕方向に+-15地球半径以内のプラズマシート中で、ジオテイル衛星が反地球向き高速流を観測する確率を計算した。その結果、オーロラ爆発が夕方で生じた場合は夕方で、真夜中で生じた場合は真夜中で、反地球向き高速流の観測確率が高かった。この結果は、反地球向き高速流の朝夕方向の位置(Y)とオーロラ爆発の経度(MLT)に対応があることを意味しており、最小自乗フィットでは、Yagsm=-5.7(MLT+0.6)Reと表せ、相関係数は0.8であった。ほとんどの反地球向き高速流はこの回帰直線から朝夕方向に5Re以内で観測されており、またそこでは反地球向き高速流の観測確率は88%であった。ジオテイル衛星の位置が回帰直線に近いにもかかわらず、反地球向き高速流が観測されなかった例が二つあったが、これらは地球向き高速流との例と、移動性圧縮領域(TCR)の例であったので、近尾部リコネクションと矛盾はしない。これらの結果から、オーロラ爆発の経度では、リコネクションは必ず生じていると考えられる。

  3. Association between auroral breakups and oxygen ions in Earth's magnetotail

    Grant number：21K03639  2021.4 - 2025.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

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    Authorship：Principal investigator 

    Grant amount：\4290000 （ Direct Cost: \3300000 、 Indirect Cost：\990000 ）

  4. Study of auroral current system using multi-satellite observations

    Grant number：16K05568  2016.4 - 2020.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Ieda Akimasa

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    Authorship：Principal investigator 

    Grant amount：\4550000 （ Direct Cost: \3500000 、 Indirect Cost：\1050000 ）

    Aurora near the midnight polar ionosphere (100 km altitude) brightens explosively approximately every a few hours. This auroral breakup is supposed to represent an electrical short of the current flowing in the magnetotail (50-200 million meters) into the ionosphere. We studied auroral breakup using simultaneous ground-satellite observations. In particular, we clarified the reason why auroral breakup jumps to a higher latitude every 10 min. We also clarified the reason why auroral breakup looks different between ground observations and satellite observations.

  5. A challenge to construct a new substorm image by coordinating ground auroral observations and in-situ spacecraft observations

    Grant number：26247082  2014.6 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    Machida Shinobu, ZENITANI Seiji, NISHIMURA Yukitoshi

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    We have conducted integrated study by analyzing the ground-based auroral imager data and the in-situ observational data from GEOTAIL, THEMIS and MMS spacecraft, and further performing numerical plasma simulations. As a result, it was found that the electron tearing mode instability takes place in the catapult current sheet, resulting in the magnetic reconnection at the near-Earth neutral line. Moreover, the resultant high-speed plasma flows toward the Earth excites instability caused by non-uniformity of the pressure, such as the ballooning instability, and generates large-scale auroral disturbances. We could obtain a new substorm model revising previous models. Furthermore, related studies have largely advanced our understanding on the magnetic reconnection.

  6. High-time resolution measurements of aurora and electromagnetic waves using ground-based observation network and satellites

    Grant number：23403009  2011.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    SHIOKAWA Kazuo, MIYOSHI Yoshizumi, OZAKI Mitunori, KATAOKA Ryuho, IEDA Akimasa, EBIHARA Yusuke, YAGITANI Satoshi

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    Authorship：Coinvestigator(s) 

    In this study we have installed new loop antennas (100-kHz sampling) to measure VLF/ELF chorus waves and auroral cameras (30-100 Hz sampling) at subauroral latitudes in Canada since 17 February, 2012. These observations reveal several previously unknown features of VLF/ELF emissions and their relation to pulsating auroras at subauroral latitudes. Routine measurements of VLF/ELF and auroras have been carried out since then, and statistical features of VLF/ELF waves have been obtained at subauroral latitudes including their relation to local time, magnetic activity, and solar wind conditions. Comparisons with conjugate satellites in the magnetospheric equatorial plane are also on going.

  7. Study of auroral current system using satellite observations and a magnetic inversion method

    Grant number：23540524  2011.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    IEDA Akimasa

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    Authorship：Principal investigator 

    Grant amount：\5070000 （ Direct Cost: \3900000 、 Indirect Cost：\1170000 ）

    The solar zenith angle (SZA) dependence of the conductance is studied and a simple theoretical form for the conductance is developed, using the peak plasma production height. The daytime electric conductance is associated with plasma created by solar extreme ultraviolet radiation incident on the neutral atmosphere of the Earth. However, it has been uncertain whether previous conductance models are consistent with the ideal Chapman theory for such plasma productions. We found that the SZA dependence of the conductance is consistent with the Chapman theory after simple modifications. An additional consideration is necessary for the Hall conductance, which decreases with increasing SZA more rapidly than the Pedersen conductance. This rapid decrease is presumably caused by a thinning of the Hall conductivity layer from noon toward nighttime. We expressed this thinning in terms of the peak production height in the Chapman theory.

  8. A frontier study for elucidating the triggering and driving mechanisms of substorms

    Grant number：22340145  2010 - 2012

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    MACHIDA Shinobu, MORIOKA Akira, IEDA Akimasa, NOSE Masahito, MIYOSHI Yoshizumi, MIYASHITA Yukinaga, HORI Tomoaki, TAKADA Taku

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    Authorship：Coinvestigator(s) 

    Substorm are known as phenomena releasing large amount of energies in both magnetosphere and ionosphere. We investigated such substorms aiming at elucidating how they are triggered and derived by analyzing data obtained by simultaneous spacecraft and ground-based observations. We confirmed the validity of the model of substorm we proposed previously. Further, we could obtain several significant features of substorm-associated auroral kilometric radiations.

  9. Study of the upper atmosphere dynamics using highly sensitive multi-point optical instruments

    Grant number：20244080  2008.4 - 2013.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    SHIOKAWA Kazuo, OTSUKA Yuichi, SAITO Akinori, MIYOSHI Yoshizumi, MATSUOKA Ayako, HIRAHARA Masafumi, HOSOKAWA Keisuke, NOZAWA Satonori, OYAMA Shinichiro, OGAWA Yasunobu, IEDA Akimasa, NISHITANI Nozomu, ISHII Mamoru, KUBOTA Minoru, OGAWA Tadahiko, YAMAMOTO Mamoru

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    Authorship：Collaborating Investigator(s) (not designated on Grant-in-Aid) 

    We have obtained various interesting results on the dynamical variations of the upper atmosphere at altitudes of 80-300 km using multi-point observation of nighttime airglow by 5 Fabry-Perot interferometers and more than 10 al-sky airglow imagers at Russia, Canada, Japan, Norway, Indonesia, Thailand, and Australia. Outstanding examples of the results are (1) various dynamical variations of medium-scale traveling ionospheric disturbances at subauroral latitudes, (2) evidence of duct propagation of small-scale gravity waves in the mesopause region, (3) evidence of a typhoon-induced small-scale gravity wave propagation to the mesopause region, and (4) relationship of eastward propagation of equatorial plasma bubbles and eastward thermospheric wind.

  10. 地磁気逆計算法を用いたオーロラ電流系の解明

    2008.4 - 2012.3

    科学研究費補助金  基盤研究(C)

    家田　章正

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    Authorship：Principal investigator 

  11. 地磁気逆計算法を用いたオーロラ電流系の解明

    2008.4 - 2012.3

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    家田 章正

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    Authorship：Principal investigator  Grant type：Competitive

    Grant amount：\3400000 （ Direct Cost: \3400000 ）

  12. High-time resolution optical observation of auroras in the Canadian arctic

    Grant number：19403010  2007 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    OGAWA Tadahiko, , SHIOKAWA Kazuo, IEDA Akimasa, NISHITANI Nozomu, HOSOKAWA Keisuke

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    Authorship：Coinvestigator(s) 

    We conduct two campaign observations of high-time resolution all-sky auroral imaging at multi-point stations in the Canadian arctic using 1/30-sec sampled cameras, in addition to the automated routine measurements of monochromatic all-sky cameras. We also combine these observations with the THEMIS satellite measurements. From these observations we obtain fine-scale structures and their development of auroras at the beginning of auroral substorms, as well as detailed characteristics of polar-cap plasma structures.

  13. Multi-dimensional Simultaneous Observations of the Geospace-Ionosphere Phenomena using Low-Altitude Polar Satellites and Ground-Based Facilities

    Grant number：19403011  2007 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    MASAFUMI Hirahara, ASAMURA Kazushi, YAMAZAKI Atsushi, SHINOHARA Iku, SAKANOI Takeshi, KASABA Yasumasa, OKANO Syoichi, MIYAOKA Hiroshi, KADOKURA Akira, OKADA Masaki, OGAWA Yasunobu, SAITO Akinori, NOZAWA Satonori, SEKI Kanako, SHIOKAWA Kazuo, IEDA Akimasa, KIKUCHI Takashi, OYAMA Shin-ichiro, EBIHARA Yusuke, TAGUCHI Makoto, HOSOKAWA Keisuke, WATARI Shinichi, MURATA Takeshi

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    Authorship：Collaborating Investigator(s) (not designated on Grant-in-Aid) 

    A micro-satellite of the Japanese mission was successfully launched from Baikonur Cosmodrome in Kazakhstan on August 23, 2005. We can simultaneously observe spatial distribution and time variation of fine aurora emissions associated with auroral electron precipitation and ionospheric ion outflows with a full pitch-angle coverage and a high-time resolution. Our Reimei team has also started some collaborative observations with EISCAT, all-sky cameras, and SuperDARN. Almost every new moon interval, we have been achieving simultaneous observations with Reimei and the ground-based instruments.

  14. 衛星観測と地磁気逆計算法によるオーロラ爆発開始条件の解明

    2005.4 - 2008.3

    科学研究費補助金  若手研究(B)

    家田　章正

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    Authorship：Principal investigator 

  15. 衛星観測と地磁気逆計算法によるオーロラ爆発開始条件の解明

    2005.4 - 2008.3

    日本学術振興会  科学研究費助成事業  若手研究(B)

    家田 章正

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    Authorship：Principal investigator  Grant type：Competitive

    Grant amount：\3600000 （ Direct Cost: \3600000 ）

  16. Highly Sensitive Optical Observations of Aurcraand Upper Atmosphere in the Canadian Arctic

    Grant number：16403007  2004 - 2006

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    OGAWA Tadahiko, SHIOKAWA Kazuo, OTSUKA Yuichi, IEDA Akimasa, NISHITANI Nozomu, HOSOKAWA Keisuke

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    Authorship：Coinvestigator(s) 

    Two all-sky airglow/aurora imagers were installed at two Canadian stations at Resolute Bay(RSB)and Athabasca observed polar-cap plasma patches almost always(ATH))in 2005, At RSB, we always during southward IMF periods, From two-dimensional cross-correlation analyses, we determined velocity vectors of the patches, which indicates the ionospheric convection vector, that showed high correlation with the IMF-By and -Bz variations. At ATH, we often observed isolated proton arcs and Stable Auroral Red (SAR) arcs, which were located equatorward of the amoral oval The appearance of the isolated proton arcs was highly correlated with the Pc 1 geomagnetic pulsations measured simultaneously at ATH, suggesting interactions between the electromagnetic ion cyclotron (EMK) waves and protons in the vicinity of the plasmapause and the ring current. Similar interactions without waves were also suggested for the SAR arcs, which appeared after the substorm expansion phase even without geomagnetic storm. These observations show promising capability monitor magnetospheric processes from the ground stations, whit would contribute to the future satellite projects such as THEMES, ERG, and Scope/Xscale

  17. 太陽地球系科学スクールに向けての企画

    Grant number：15634012  2003

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    上出 洋介, 荻野 竜樹, 増田 智, 関 華奈子, 西谷 望, 家田 章正

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    Authorship：Coinvestigator(s) 

    世界中から講師と学生/若手研究者を招き、太陽地球系科学の国際スクールを日本さ開催するため計画を持っている。本研究では、その実現に向けての企画調査を行なった。まず、当該分野でこの数年間に実施されたサマースクールの開催責任者から、経験に基づく体制づくりに関するノウハウを学び、続いて国際学術団体、学会連合から講義課題についての希望調査を行なった。また、以前から共催が要請されているWISER(World Institute for Space Environment Research)本部(ブラジル国立宇宙科学研究所)を訪問し、具体的な条件、可能な共同体制、3カ年計画での講義/シンポジウム、スクール終了後の教科書出版の議論を行なった。それらの調査をもとに、国内研究分担者による準備検討会を開催し、意見を集約した。得られた主な結論は次の通りである。
    1.国際スクールは、講義(午前中)とパネルディスカッション(午後)で構成される。請義では、基礎、最新のトピックスを扱う。パネルディスカッションは、主として最近の相反する理論、モデリングについて、スクールの学生が主導し、講師はアドバイザーとして参加する。開校は5日間(月-金曜日)。3年間続けることが望ましい。
    2.講師は、退官した、当該分野の開拓者レベルとする。著名なメダル/賞の受賞者に限る。学生は、世界の大学、研究所から推薦された70名程度(うち、日本人は10名以内)とする。
    3.このスクールから、3年連続で教科書を出版する。出版は、Cambridge University Press, Springer Verlagなどから選択する。
    4.学生には滞在費/食事代を提供する。旅費は各自の機関もちとする。ただし、発展途上国からの参加者には旅費も支給する。
    5.講師候補者約60名のリストアップを行なった。

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To the head of KAKENHI (Grants-in-Aid for Scientific Research).▲