Special Particle Precipitation Signatures Over Giant Auroral Undulations During the 7 September 2015 Geomagnetic Storm

Abstract

Giant undulations (GUs) have been well established to be the optical manifestation of the plasmapause surface wave (PSW) where the wave‐particle interactions provide particle sources to generate auroras. However, their detailed particles precipitation signatures in the ionosphere remain unclear. Here we analyze multi‐satellite conjugated observations in the ionosphere during a prominent GUs event, revealing the two‐zone precipitation pattern including energetic proton precipitations responsible for the main body of GUs and low‐energy electron precipitations for the edge of GUs. Interestingly, the occurrence of GUs is also accompanied with high‐energy particles precipitations of hundreds of keV and magnetic disturbances of three components. The sizes of sawtooth in the GUs correlate positively with the strength of adjacent subauroral polarization streams (SAPS). The two‐zone precipitation pattern and high‐energy particles precipitation over GUs are potentially related to the plasma sheet and very‐low frequency wave (VLF) modulation of the PSW, respectively.