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
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(12). https://doi.org/10.1002/2017JA024548