Oral Presentation
Evaluation of wave normal and Poynting vector for whistler mode waves observed by the waveform capture (WFC) on board the Arase
Presenter: Yoshiya Kasahara (Kanazawa University)
The Plasma Wave Experiment (PWE) on board the Arase (ERG) satellite is designed to measure electric field from DC to 10 MHz and magnetic field from a few Hz to 100 kHz. The waveform capture (WFC) is one of subsystems of the PWE and is dedicated to measuring waveform for the two electric components and three magnetic field components. WFC aims at detailed observation of plasma waves in the VLF range such as chorus, hiss and lightning whistler in the Earth’s inner magnetosphere.
In the present paper, we introduce direction finding results (wave normal vectors and Poynting vectors) derived from whistler mode waves measured by the WFC. In order to estimate these parameters in accurate, it is inevitable to calibrate the gain and phase of the waveform using frequency responses of sensors and receivers. Particularly the electric field data needs to be corrected in consideration of the antenna impedance of the sensor which depends on the electron density and temperature at the observation point. In the present study, we first derive the wave normal directions and refractive indexes from the observed data and compared them with the ones theoretically derived from the Appleton-Hartley dispersion relation. We demonstrated that the results were generally reliable, but further calibration is necessary considering not only electron density but also electron temperature. In the presentation, we introduce some typical results which have been derived from the data when upper- and lower-band chorus, and lightning whistlers were observed by the Arase.
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