SM006-0005
Cold ionospheric ion dynamics inside an EMIC wave in the inflow region of dayside magnetopause reconnection

Monday, 7 December 2020
Poster
Sergio Toledo Redondo1, Justin H Lee2, Sarah K. Vines3, Drew L. Turner4, Robert Colby Allen4, Mats Andre5, Scott A Boardsen6, James L Burch7, Richard Eugene Denton8, Huishan Fu9, Stephen A Fuselier10, Daniel J Gershman11, Barbara L Giles11, Daniel Graham12, Naritoshi Kitamura13, Yuri Khotyaintsev14, Benoit Lavraud15, Olivier Le Contel16, Wenya Li12, Thomas Earle Moore17 and Adolfo F. Vinas11, (1)University of Murcia, Murcia, Spain, (2)The Aerospace Corporation, Los Angeles, CA, United States, (3)University of Texas at San Antonio, San Antonio, TX, United States, (4)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (5)Swedish Inst Space Physics, Uppsala, Sweden, (6)NASA Goddard SFC, Greenbelt, MD, United States, (7)Southwest Research Institute San Antonio, San Antonio, TX, United States, (8)Dartmouth College, Department of Physics and Astronomy, Hanover, NH, United States, (9)Beihang University, Beijing, China, (10)Southwest Research Institute, San Antonio, TX, United States, (11)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (12)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (13)The University of Tokyo, Tokyo, Japan, (14)IRF Swedish Institute of Space Physics, Uppsala, Sweden, (15)IRAP/CNRS, Toulouse, France, (16)Laboratoire de Physique des Plasmas (UMR7648), CNRS/Ecole Polytechnique/UPMC/Univ. Paris Sud/Obs. de Paris, Paris, France, (17)NASA Goddard Space Flight Ctr, Greenbelt, MD, United States
Abstract:
We report detailed observations, using the Magnetospheric Multiscale mission, of the ion dynamics inside an Alfvén branch wave that travels tangential to the reconnecting dayside magnetopause on the magnetospheric side of the magnetopause boundary. The measured wave properties are in excellent agreement with linear theory, showing that the wave corresponds to an electromagnetic ion cyclotron wave. The magnetospheric plasma is composed of plasma sheet-originating ions (several keV temperature) and cold, ionospheric-originating ions (~10 eV), which exhibit different dynamics inside the wavefront. The cold ions follow the magnetic field fluctuations and remain frozen-in, while the hot ions, owing to their large gyroradius, are partially demagnetized inside the wavefront. The energy source of the wave is the hot ion anisotropy, and the cold ions also exchange energy and momentum with the wave. The cold ion velocity fluctuations contribute to balance the Hall term of the Ohm's law. In this regime, the cold ions exchange energy back and forth with the fields. On the other hand, the hot ions are in a kinetic regime, allowing irreversible energy transfer with the wave electromagnetic fields. Since the wave is adjacent to the reconnecting magnetopause, the effects of the wave on the local plasma near the magnetopause preconditions the ion populations flowing into the magnetospheric reconnection inflow region.
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