EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Kinetic interaction of cold and hot protons with an oblique EMIC wave near the dayside reconnecting magnetopause

Sergio Toledo-Redondo1,2, Justin H. Lee3, Sarah K. Vines4, Drew L. Turner4, Robert C. Allen4, Mats André5, Scott A. Boardsen6, James L. Burch7, Richard E. Denton8, Huishan Fu9, Stephen A. Fuselier7, Barbara Giles6, Naritoshi Kitamura10, Yuri V. Khotyaintsev5, Benoit Lavraud2, Olivier LeContel11, Wenya Li12, Enrique A. Navarro13, Jorge Portí14, and Alfonso Salinas15
Sergio Toledo-Redondo et al.
  • 1University of Murcia, Murcia, Spain (
  • 2Institut de Recherche en Astrophysique et Planetologie, Universite de Toulouse, CNRS, UPS, CNES
  • 3The Aerospace Corporation, El Segundo, CA, USA
  • 4The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
  • 5Swedish Institute of Space Physics, Uppsala, Sweden
  • 6NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 7Southwest Research Institute, San Antonio, Texas, USA
  • 8Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire, USA
  • 9School of Space and Environment, Beihang University, Beijing, China
  • 10Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Tokyo, Japan
  • 11Laboratoire de Physique des Plasmas (LPP), UMR7648 CNRS/Ecole Polytechnique Institut Polytechnique de Paris/Sorbonne Université/Université Paris Saclay/Observatoire de Paris, Paris, France
  • 12State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, 100190, China
  • 13Department of Applied Physics, Universitat de Valencia, Valencia, Spain
  • 14Department of Applied Physics, University of Granada, Granada, Spain
  • 15Department of Electromagnetism and Matter Physics, University of Granada, Granada, Spain

We report observations of the ion dynamics inside an Alfven branch wave that propagates near the reconnecting dayside magnetopause. The measured frequency, wave normal angle and polarization are within 1% with the predictions of a dispersion solver, and indicate that the wave is an electromagnetic ion cyclotron wave with very oblique wave vector. The magnetospheric plasma contains hot protons (keV), cold protons (eV), plus some heavy ions. The cold protons follow the magnetic field fluctuations and remain frozen-in, while the hot protons are at the limit of magnetization.

The cold proton velocity fluctuations contribute to balance the Hall term in Ohm's law, allowing the wave polarization to be highly-elliptical and right-handed, a necessary condition for propagation at oblique wave normal angles. The dispersion solver indicates that increasing the cold proton density facilitates generation and propagation of these waves at oblique angles, as it occurs for the observed wave.

How to cite: Toledo-Redondo, S., Lee, J. H., Vines, S. K., Turner, D. L., Allen, R. C., André, M., Boardsen, S. A., Burch, J. L., Denton, R. E., Fu, H., Fuselier, S. A., Giles, B., Kitamura, N., Khotyaintsev, Y. V., Lavraud, B., LeContel, O., Li, W., Navarro, E. A., Portí, J., and Salinas, A.: Kinetic interaction of cold and hot protons with an oblique EMIC wave near the dayside reconnecting magnetopause, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7351,, 2021.

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