The properties of large amplitude whistler mode waves in the magnetosphere: Propagation and relationship with geomagnetic activity

摘要

We present results of a study of the characteristics of very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 R_E using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had ≥80 mV/m peak-to-peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had ≥0.8 nT peak-to-peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20° of the ambient magnetic field, though some are more oblique (up to ～50°). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (≈8 nT peak-to-peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ≈300 μW/m~2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons.