Study of VLF band electromagnetic waves in the Antarctica observed by Polar Patrol Balloons

摘要

We developed the wide-band electromagnetic wave receiver, named BMW, onboard PPB scientific balloons to observe waveforms of ELF band waves and power spectra of VLF band waves over the Antarctica. EMW receiver worked properly during all the PPB experiment, and observed a variety of plesrna waves such as Pc1 pulsations, ELF hiss, polar chorus and auroral hiss. According to the cross correlation analysis, we found the VLF whistler waves observed by two balloons successively with the interval of 3 seconds. These waves are estimated to be excited by the compressional Alfven waves propagating across the Earth's magnetic fields, propagate along the Earth's magnetic fields, and then observed by two balloons. This model is consistent with the modulation model of VLF waves which have been considered. This is the first result of the formation flight of two balloons in plasma wave observations, Since the observation times in two balloons are completely synchronized with GPS 1pps pulse signals, we can separate spatial and temporal variations of the observation results. Further, we will investigate the relation between VLF band waves and compressional Alfven waves in detail with using VLF wave data observed at Syowa Station. In addition, we have made a campaign observation with the ELF/VLF wave instrument onboard Ake-bono satellite during this PPB experiments. We will make three-dimensional analysis of ELF/VLF wave phenomena with using wave data observed by Akebono satellite.