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Daytona Beach


Physical Sciences

Document Type


Publication/Presentation Date



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.

Publication Title

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