Kelvin-Helmholtz waves at the Earth's magnetopause: Multiscale development and associated reconnection

H. Hasegawa, A. Retinó, A. Vaivads, Y. Khotyaintsev, M. André, T. K M Nakamura, Teh Wai Leong, B. U Ö Sonnerup, S. J. Schwartz, Y. Seki, M. Fujimoto, Y. Saito, H. Rème, P. Canu

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Abstract

We examine traversais on 20 November 2001 of the equatorial magnetopause boundary layer simultaneously at ∼ 1500 magnetic local time (MLT) by the Geotail spacecraft and at ∼1900 MLT by the Cluster spacecraft, which detected rolled-up MHDscale vortices generated by the Kelvin-Helmholtz instability (KHI) under prolonged northward interplanetary magnetic field conditions. Our purpose is to address the excitation process of the KHI, MHD-scale and ion-scale structures of the vortices, and the formation mechanism of the low-latitude boundary layer (LLBL). The observed KH wavelength (>4 × 104 km) is considerably longer man predicted by the linear theory from the thickness (∼1000 km) of the dayside velocity shear layer. Our analyses suggest that the KHI excitation is facilitated by combined effects of the formation of the LLBL presumably through high-latitude magnetopause reconnection and compressional magnetosheath fluctuations on the dayside, and that breakup and/or coalescence of the vortices are beginning around 1900 MLT. Current layers of thickness a few times ion inertia length ∼100 km and of magnetic shear ∼60° existed at the trailing edges of the vortices. Identified in one such current sheet were signatures of local reconnection: Alfvénic outflow jet within a bifurcated current sheet, nonzero magnetic field component normal to the sheet, and field-aligned beam of accelerated electrons. Because of its incipient nature, however, this reconnection process is unlikely to lead to the observed dusk-flank LLBL. It is thus inferred that the flank LLBL resulted from other mechanisms, namely, diffusion and/or remote reconnection unidentified by Cluster.

Original languageEnglish
Article numberA12207
JournalJournal of Geophysical Research: Space Physics
Volume114
Issue number12
DOIs
Publication statusPublished - 2009
Externally publishedYes

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Magnetopause
magnetopause
boundary layers
Boundary layers
tropical regions
boundary layer
Kelvin-Helmholtz instability
Earth (planet)
vortex
Vortex flow
vortices
current sheets
magnetic fields
shear stress
Spacecraft
spacecraft
Ions
ions
Magnetic fields
magnetic field

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics

Cite this

Hasegawa, H., Retinó, A., Vaivads, A., Khotyaintsev, Y., André, M., Nakamura, T. K. M., ... Canu, P. (2009). Kelvin-Helmholtz waves at the Earth's magnetopause: Multiscale development and associated reconnection. Journal of Geophysical Research: Space Physics, 114(12), [A12207]. https://doi.org/10.1029/2009JA014042

Kelvin-Helmholtz waves at the Earth's magnetopause : Multiscale development and associated reconnection. / Hasegawa, H.; Retinó, A.; Vaivads, A.; Khotyaintsev, Y.; André, M.; Nakamura, T. K M; Wai Leong, Teh; Sonnerup, B. U Ö; Schwartz, S. J.; Seki, Y.; Fujimoto, M.; Saito, Y.; Rème, H.; Canu, P.

In: Journal of Geophysical Research: Space Physics, Vol. 114, No. 12, A12207, 2009.

Research output: Contribution to journalArticle

Hasegawa, H, Retinó, A, Vaivads, A, Khotyaintsev, Y, André, M, Nakamura, TKM, Wai Leong, T, Sonnerup, BUÖ, Schwartz, SJ, Seki, Y, Fujimoto, M, Saito, Y, Rème, H & Canu, P 2009, 'Kelvin-Helmholtz waves at the Earth's magnetopause: Multiscale development and associated reconnection', Journal of Geophysical Research: Space Physics, vol. 114, no. 12, A12207. https://doi.org/10.1029/2009JA014042
Hasegawa, H. ; Retinó, A. ; Vaivads, A. ; Khotyaintsev, Y. ; André, M. ; Nakamura, T. K M ; Wai Leong, Teh ; Sonnerup, B. U Ö ; Schwartz, S. J. ; Seki, Y. ; Fujimoto, M. ; Saito, Y. ; Rème, H. ; Canu, P. / Kelvin-Helmholtz waves at the Earth's magnetopause : Multiscale development and associated reconnection. In: Journal of Geophysical Research: Space Physics. 2009 ; Vol. 114, No. 12.
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AU - Retinó, A.

AU - Vaivads, A.

AU - Khotyaintsev, Y.

AU - André, M.

AU - Nakamura, T. K M

AU - Wai Leong, Teh

AU - Sonnerup, B. U Ö

AU - Schwartz, S. J.

AU - Seki, Y.

AU - Fujimoto, M.

AU - Saito, Y.

AU - Rème, H.

AU - Canu, P.

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