Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF

Blasl, K. A., Nakamura, T. K. M., Plaschke, F., Nakamura, R., Hasegawa, H., Stawarz, Julia, Liu, Yi-Hsin, Peery, S., Holmes, J. C., Hosner, M., Schmid, D., Roberts, O. W. and Volwerk, M. (2022) Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF. Physics of Plasmas, 29 (1). 012105. ISSN 1070-664X

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In this study, we present the first observations from the Magnetospheric Multiscale (MMS) mission of the Kelvin-Helmholtz instability (KHI) at the dusk-flank magnetopause during southward interplanetary magnetic field conditions on September 23, 2017. The instability criterion for the KHI was fulfilled for the plasma parameters observed throughout the event. An analysis of the boundary normal vectors based on the application of the timing method onto the magnetic field and the electron density data and the minimum directional derivative method onto the magnetic field data shows signatures of surface waves in the plane parallel to the velocity shear. A comparison to 2D fully kinetic simulations demonstrates reasonable consistencies with the formation of surface waves generated by the KH instability, as well as the structures of rolled-up KH waves. The observations further indicated low density faster than sheath plasma as an indicator of rolled-up vortices, which is also consistent with the simulations. All of these results show that the observed waves and vortices are most likely generated by the KH instability. High-time resolution MMS measurements further demonstrate kinetic-scale electric field fluctuations on the low-density side of the edges of surface waves. Detailed comparisons with the simulations suggest that the observed fluctuations are generated by the lower-hybrid drift instability excited by the density gradient at the edges of these surface waves. These secondary effects can lead to a flattening of the edge layers, indicating the connection between kinetic and larger scales within the KH waves and vortices.

Item Type: Article
Additional Information: Funding Information: This work was supported by the Austrian Science Fund (FWF), Grant No. P32175-N27. For the simulations employed in this paper, we acknowledge PRACE for giving us access to MareNostrum at the Barcelona Supercomputing Center (BSC), Spain. A part of the simulation data was analyzed with resources at the Space Research Institute of the Austrian Academy of Sciences. The work by H.H. was supported by JSPS Grant-in-aid for Scientific Research KAKENHI 21K03504. J.E.S. was supported by the Royal Society University Research Fellowship URF\R1\201286. The observational data employed in this paper were obtained from the MMS spacecraft and are publicly available via NASA resources and the Science Data Center at CU/LASP (https:// They were analyzed using the SPEDAS44 software package for IDL ( The wave-power spectra in Fig. 10 were obtained using the routine of SPEDAS.
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 09 Dec 2022 12:11
Last Modified: 09 Dec 2022 12:15

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