Using data from Time History of Events and Macroscale Interactions during Substorms (THEMIS), a statistical study was performed to determine whether a dawn-dusk asymmetry exists in the occurrence rates of the Kelvin-Helmholtz (KH) instability during Parker-Spiral (PS) and Ortho-Parker-Spiral (OPS) orientations of the interplanetary magnetic field (IMF). It is determined from the data that there is a strong preference toward the dawn side during PS orientation, and although a preference to the dusk side during OPS is suggested, this requires further study for an unambiguous confirmation. The uncertainty in the OPS result is due to a low number of events which satisfied our selection criteria. Because IMF is statistically in PS orientation, the KHI preference for the dawn-flank during this orientation may help explain the origin of the plasma sheet asymmetry of cold-component ions because it has been shown that KHI can drive kinetic-scale wave activity capable of ion heating.
Journal of Geophysical Research: Space Physics
American Geophysical Union
Grant or Award Name
NSF GEM grant 1502774, NASA grant NNX16AF89G, Academy of Finland grant 288476
Scholarly Commons Citation
Henry, Z. W., Nykyri, K., Moore, T. W., Dimmock, A. P., & Ma, X. (2017). On the dawn-dusk asymmetry of the Kelvin-Helmholtz instability between 2007 and 2013. Journal of Geophysical Research: Space Physics, 122. https://doi.org/10.1002/2017JA024548