Investigating the Role of Magnetosheath High‐Speed Jets in Triggering Dayside Ground Magnetic Ultra‐Low Frequency Waves

Abstract

AbstractUltra‐low frequency (ULF) waves significantly contribute to transferring energy and transporting particles in the coupled magnetosphere‐ionosphere system. Recent studies suggested magnetosheath high‐speed jets (HSJs) can drive magnetospheric ULF waves, but whether they can be an important source of dayside ground magnetic ULF oscillations has not been examined thoroughly. Utilizing 5 years of observations by the Time History of Events and Macroscale Interactions During Substorms satellites and ground‐based magnetometers, we found that 37% of all the observed magnetosheath HSJs can trigger ground magnetic field oscillations and were thus determined as geoeffective HSJs. The occurrence rate has positive relationship with increasing flow speed and dynamic pressure of magnetosheath HSJs. We propose that magnetosheath HSJs can be a source of dayside ground magnetic ULF oscillations. We also identified the different behaviors of isolated and recurrent magnetosheath HSJs in generating ground magnetic ULF oscillations. The recurrence time of recurrent magnetosheath HSJs likely determines the frequencies of the ULF oscillations.