日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM13] 内部磁気圏

2019年5月29日(水) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:海老原 祐輔(京都大学生存圏研究所)、Danny Summers(Memorial University of Newfoundland)、三好 由純(名古屋大学宇宙地球環境研究所)、齊藤 慎司(名古屋大学 大学院理学研究科)

[PEM13-P01] Evaluation of wave normal and Poynting vector analyses for whistler mode waves observed by the waveform capture (WFC) on board the Arase

*笠原 禎也1五十嵐 智1西澤 宏幸1松田 昇也2土屋 史紀3熊本 篤志3笠羽 康正3尾崎 光紀1松岡 彩子2 (1.金沢大学、2.宇宙科学研究所、3.東北大学)

キーワード:ホイスラーモード波、波形捕捉受信器、到来方向推定、プラズマ波動

The Plasma Wave Experiment (PWE) is one of scientific instruments on board the Arase (ERG) satellite to measure electric field from DC to 10 MHz and magnetic field from a few Hz to 100 kHz in the inner magnetosphere. It is well known that chorus wave, one of typical plasma waves in VLF range observed in the inner magnetosphere, is a plausible candidate that accelerates relativistic electrons in the radiation belt. Besides the chorus, the Arase has observed various kinds of plasma waves such as lightning whistlers and hiss waves. It is very important to study the propagation characteristics of these waves.

In the present paper, we developed a direction finding system applicable to whistler mode waves using the data from waveform capture (WFC), which is one of receivers covering the frequency range below 20kHz implemented in the PWE. The absolute directions of the wave normal and Poynting vectors were derived in the coordinate system referring the ambient magnetic field and geomagnetic meridian plane. We also estimated the Poynting vector theoretically using the derived wave normal vector, electron density and ambient magnetic field intensity to confirm the validity of the results from the observation data.

We demonstrated that the results were generally reliable, but further calibration is necessary for electric field to improve the accuracy of Poynting vector because the waveform of electric field is now calibrated under the assumptions of theoretical antenna capacitance in a vacuum and typical plasma impedance. In other words, we expect to be able to correct the calibration table for electric field measurements from the direction finding results.

In the presentation, we introduce some typical results which have been derived from the observation data of upper- and lower-band chorus, and lightning whistlers.