Letter | Published:

Pulsating aurora from electron scattering by chorus waves

Nature volume 554, pages 337340 (15 February 2018) | Download Citation

Abstract

Auroral substorms, dynamic phenomena that occur in the upper atmosphere at night, are caused by global reconfiguration of the magnetosphere, which releases stored solar wind energy1,2. These storms are characterized by auroral brightening from dusk to midnight, followed by violent motions of distinct auroral arcs that suddenly break up, and the subsequent emergence of diffuse, pulsating auroral patches at dawn1,3. Pulsating aurorae, which are quasiperiodic, blinking patches of light tens to hundreds of kilometres across, appear at altitudes of about 100 kilometres in the high-latitude regions of both hemispheres, and multiple patches often cover the entire sky. This auroral pulsation, with periods of several to tens of seconds, is generated by the intermittent precipitation of energetic electrons (several to tens of kiloelectronvolts) arriving from the magnetosphere and colliding with the atoms and molecules of the upper atmosphere4,5,6,7. A possible cause of this precipitation is the interaction between magnetospheric electrons and electromagnetic waves called whistler-mode chorus waves8,9,10,11. However, no direct observational evidence of this interaction has been obtained so far12. Here we report that energetic electrons are scattered by chorus waves, resulting in their precipitation. Our observations were made in March 2017 with a magnetospheric spacecraft equipped with a high-angular-resolution electron sensor and electromagnetic field instruments. The measured13,14 quasiperiodic precipitating electron flux was sufficiently intense to generate a pulsating aurora, which was indeed simultaneously observed by a ground auroral imager.

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References

  1. 1.

    Polar and Magnetospheric Substorms 22–31, 222–224 (Springer, 1968)

  2. 2.

    et al. Tail reconnection triggering substorm onset. Science 321, 931–935 (2008)

  3. 3.

    & Aurorae and closed magnetic field lines. J. Atmos. Terr. Phys. 39, 1429–1434 (1977)

  4. 4.

    Pulsating aurora. Nature 274, 119–126 (1978)

  5. 5.

    & A campaign to study pulsating auroras. Can. J. Phys. 59, 1029–1033 (1981)

  6. 6.

    in Auroral Phenomenology and Magnetospheric Processes: Earth And Other Planets (eds et al.) 55–68 (American Geophysical Union, 2012)

  7. 7.

    et al. Origins of the Earth’s diffuse auroral precipitation. Space Sci. Rev. 200, 205–259 (2016)

  8. 8.

    , , , & Scattering by chorus waves as the dominant cause of diffuse auroral precipitation. Nature 467, 943–946 (2010)

  9. 9.

    et al. Identifying the driver of pulsating aurora. Science 330, 81–84 (2010)

  10. 10.

    et al. Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions. J. Geophys. Res. 116, A11221 (2011)

  11. 11.

    et al. Relation between fine structure of energy spectra for pulsating aurora electrons and frequency spectra of whistler mode chorus waves. J. Geophys. Res. Space Phys. 120, 7728–7736 (2015)

  12. 12.

    , , , & Pulsating auroras produced by interactions of electrons and time domain structures. J. Geophys. Res. Space Phys. 122, 8604–8616 (2017)

  13. 13.

    et al. in Dynamics of the Earth's Radiation Belts and Inner Magnetosphere (eds et al.) 103–116 (American Geophysical Union, 2012)

  14. 14.

    et al. Geospace exploration project: Arase (ERG). J. Phys. Conf. Ser. 869, 012095 (2017)

  15. 15.

    & Limit on stably trapped particle fluxes. J. Geophys. Res. 71, 1–28 (1966)

  16. 16.

    , & A circulating cyclotron maser and pulsed VLF emissions. Geomagn. Aeron. 26, 77–82 (1986)

  17. 17.

    et al. Pulsating auroral electron flux modulations in the equatorial magnetosphere. J. Geophys. Res. Space Phys. 118, 4884–4894 (2013)

  18. 18.

    et al. The THEMIS array of ground-based observatories for the study of auroral substorms. Space Sci. Rev. 141, 357–387 (2008)

  19. 19.

    & Modeling the dynamics of the inner magnetosphere during strong geomagnetic storms. J. Geophys. Res. 110, A03208 (2005)

  20. 20.

    et al. Estimation of magnetic field mapping accuracy using the pulsating aurora-chorus connection. Geophys. Res. Lett. 38, L14110 (2011)

  21. 21.

    & Potential waves for relativistic electron scattering and stochastic acceleration during magnetic storms. Geophys. Res. Lett. 25, 3011–3014 (1998)

  22. 22.

    , , & An empirical plasmasphere and trough density model: CRRES observations. J. Geophys. Res. 106, 25631–25641 (2001)

  23. 23.

    , , & Magnetospheric source region of discrete auroras inferred from their relationship with isotropy boundaries of energetic particles. Ann. Geophys. 15, 943–958 (1997)

  24. 24.

    et al. Whistler mode chorus enhancements in association with energetic electron signatures in the Jovian magnetosphere. J. Geophys. Res. 116, A02215 (2011)

  25. 25.

    et al. Saturn chorus intensity variations. J. Geophys. Res. Space Phys. 118, 5592–5602 (2013)

  26. 26.

    et al. Cusp type electrostatic analyzer for measurements of medium energy charged particles. Rev. Sci. Instrum. 77, 123303 (2006)

  27. 27.

    , & Variability of the minimum detectable energy of an APD as an electron detector. Nucl. Instr. Meth. A 664, 282–288 (2012)

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Acknowledgements

The observations presented here were obtained with the help of Mitsubishi Heavy Industries, Ltd, Meisei Electric Co., Ltd, Hamamatsu Photonics Co. Ltd, YS DESIGN Co., Ltd, NIPPI Co. Ltd, Sumitomo Heavy Industries, Ltd and TIERRA TECNICA Co. Ltd. We acknowledge the work of the members of the ERG project team over several years. Y.M. is supported by JSPS Kakenhi (15H05747, 15H05815 and 16H06286). Y. Kasahara is supported by JSPS Kakenhi (16H04056 and 16H01172). H.U.F. is supported by grant AGS-1004736 from the National Science Foundation (NSF) of the USA. I.S. is supported by JSPS Kakenhi (17H06140). We thank NASA for contract NAS5-02099, S. Mende and E. Donovan for use of the ASI data, the Canadian Space Agency for logistical support in fielding and data retrieval from the ground-based observatory stations, and the NSF for support of the Ground-based Imager and Magnetometer Network for Auroral Studies programme through grant AGS-1004736. The ERG (Arase) satellite science data is available from the ERG Science Centre operated by the Institute of Space and Astronautical Science of the Japan Aerospace eXploration Agency and the Institute for Space–Earth Environmental Research of Nagoya University (https://ergsc.isee.nagoya-u.ac.jp/index.shtml.en). We are grateful to J. Hohl for assistance in editing the manuscript. We also thank N. Umemura for assistance in source data archiving. S. Kasahara thanks T. Mukai and M. Fujimoto for discussions.

Author information

Affiliations

  1. Department of Earth and Planetary Science, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan

    • S. Kasahara
    • , K. Keika
    •  & K. Seki
  2. Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, 24105 Nagoya, Aichi, Japan

    • Y. Miyoshi
    • , S. Matsuda
    •  & S. Kurita
  3. Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, Japan

    • S. Yokota
  4. Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa, Japan

    • T. Mitani
    • , A. Matsuoka
    •  & I. Shinohara
  5. Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, Japan

    • Y. Kasahara
  6. Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578 Japan

    • A. Kumamoto
  7. Academia Sinica Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, AS/NTU, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan

    • Y. Kazama
  8. Space Sciences Laboratory, University of California, Berkeley, California 94720-7450, USA

    • H. U. Frey
  9. Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, California 90095-1567, USA

    • V. Angelopoulos

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Contributions

S. Kasahara developed the MEP-e instrument used in this study with S.Y. and T.M., identified the event, analysed the combined dataset and wrote the paper. Y.M. oversaw the production of the combined dataset and discussed its interpretation. Y. Kasahara, S.M. and A.K. provided Plasma Wave Experiment data and discussed the interpretation. A.M. provided MaGnetic Field experiment data. Y. Kazama assisted in the evaluation of MEP-e data through comparison with the Low-Energy Particle experiments – electron analyser. H.U.F. and V.A. provided ASI/THEMIS data and discussed the event and presentation of the results. S. Kurita evaluated the spacecraft footprint with Y.M. and discussed the event. K.K. and K.S. discussed the event and presentation. I.S. oversaw the ERG project and discussed the interpretation of the event. All authors reviewed the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to S. Kasahara.

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Extended data

Supplementary information

Videos

  1. 1.

    Auroral motions obtained by all-sky imagers

    Successive clear sky images from two ground stations (Fort Simpson at the upper left, and The Pas at the lower right) are shown as a video. The red cross indicates the nominal spacecraft footprint. Dashed lines illustrate magnetic coordinates every 10o in latitude and 15o in longitude. The presented time period covers that of Fig. 3.

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DOI

https://doi.org/10.1038/nature25505

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