Statistical Survey of Ion Cyclotron Wave Signatures around Earth's Magnetotail Dipolarizations

In the Earth’s magnetotail fast earthward plasma flows (so-called Bursty Bulk Flows) are often associated with dipolar magnetic flux bundles. The leading edges of such earthward-moving flux bundles are called dipolarization fronts (DF). Previous studies have reported wave signatures around the local proton cyclotron frequency during selected events, using data from the Cluster, THEMIS and MMS missions. In the present study, we examine characteristics of these ion-scale waves during several hundred DF events, observed by NASA’s Magnetospheric Multiscale mission (MMS) between 2017 and 2022. By applying a wavelet analysis to the database, we not only obtain a statistical picture of the waves from spectral parameters such as the polarization, propagation direction, and electromagnetic character. It also allows us to map their temporal distribution around the DFs, and to obtain a global picture about the occurrence of such waves across different regions of the magnetotail, including the central plasma sheet, the outer plasma sheet, and the plasma sheet boundary layer. Based on the analysis we discuss possible generation mechanisms of the waves.