Study of Auroral VLF Hiss Observed at Syowa Station, Antarctica
スポンサーリンク
概要
- 論文の詳細を見る
Observations of polarization, incident angle and arriving direction of auroral hiss were carried out at Syowa Station during the period of 1967 to 1970. The present paper consists of two parts. In Part I, we describe the equipment used for the measurement of polarization, incident and azimuthal angles and show the obtained results. The direction finding (DE) system used is based on the analysis of Lissajous' figures of electric and magnetic fields displayed on cathode ray tubes. The individual polarization of the received signal is also measured. Moreover, auroral hiss is decomposed into right-and left-handed polarized components, and these two components are continuously recorded. From the discussion of the observed results, it is found that auroral hiss has propagated downward in the azimuthal direction from a not so broad range around the magnetic meridian plane and its incident angle is also not so large. Additionally, in most cases, auroral hiss is known to consist of wave components downcoming from multiple directions in the azimuthal and incident planes. The DF system used was found to be effective in a few cases of isolated and sharp auroral hiss. However, this system should be re-examined because it is, strictly speaking, useful only for monochromatic waves, while the auroral hiss seems to have a noise-like nature. Therefore, a new DF system applying the correlation method is being planned to study, with more accuracy, the azimuthal and incident angles of noisy signals such as auroral hiss. The polarization of auroral hiss received on the ground seems to be almost right-handed circular, at VLF and LF, which is theoretically confirmed by the full wave calculation of the polarization using the realistic model of the auroral ionosphere. On the other hand, the observed polarization of ELF hiss is slightly right-handed circular, which can be reasonably accepted, taking into consideration the result of the full, wave calculation. In Part II, the morphological characteristics of auroral hiss are discussed in comparison with those of low-latitude hiss using the VLF data observed at Syowa Station and at Moshiri in Japan. Auroral hiss, considered to be a manifestation of polar substorms, is a local phenomenon and its frequency extends from a few kHz to more than 100 kHz. Low-latitude hiss, however, is closely correlated with worldwide geomagnetic storms and it is a narrow band VLF phenomenon. Together with other differences between them, it is concluded that auroral hiss is completely different from low-latitude hiss. Although the morphological features of auroral hiss have been well known, a complete understanding of its generation mechanism has not yet been obtained. There are unsolved problems such as about two orders shortening of the calculated intensity below the observations and the existence of the threshold low-energy electron flux below which VLF hiss is not observed. These facts may suggest that a coherent plasma instability mechanism is partially involved in the generation of auroral hiss. Therefore, the investigation of the coherency of auroral hiss being planned by us may give a better understanding of the generation processes of auroral hiss.
- 国立極地研究所の論文
著者
-
Hayakawa Masashi
Research Institute of Atmospherics, Nagoya University
-
Tanaka Yoshihito
Research Institute Of Atmospherics Nagoya University
-
Nishino Masanori
Research Institute of Atmospherics, Nagoya University
-
Hayakawa Masashi
Research Institute Of Atmospherics Nagaya University
-
Hayakawa Masashi
Research Institute Of Atmospherics Nagoya University
-
Nishino Masanori
Research Institute Of Atmospherics Nagoya University
-
Nishino Masanori
Research Institute Of Atmospherics Nagaya University
-
Tanaka Yoshihito
Research Institute Of Atmospherics Nagaya University
-
Tanaka Yoshihito
Research Institute of Atmospherics, Nagoya University
関連論文
- On the statistical properties of magnetospheric ELF/VLF hiss
- Measurement of Auroral Electric Fields with an Antarctic Sounding Rocket S-310JA-7. 1.DC Electric Field
- GEOS-1 observation of hiss-triggered chorus emissions in the outer magnetosphere and their generation model
- The wave normal directions of chorus emissions in the outer magnetosphere
- On the observed results of the intensity and the polarization of narrow-band auroral hiss emissions
- Comprarison between the arrival direction of auroral hiss and the location of aurora observed at Syowa Station
- Observation of Auroral Hiss by the S-310JA-6 Sounding Rocket
- A New Direction-Finding System for Auroral Hiss in Antarctica Besed on the Measurement of Time Difference of Wave Arrival at Three Spaced Observing Points
- Low-latitude Pi 1-2 magnetic pulsations of the August 28, 1986 substorm event
- Characteristics of Pc 3 magnetic pulsations in conjugate area around L=1.3-2.1
- Pc 3 magnetic pulsations observed at low latitudes: A possible model
- The Results of Auroral Sounding with S-310JA-4 Rocket: Electric Field, Particle and Waves
- Synthetic Observations of High-Latitude Ionosphere by S-310JA-4 Sounding Rocket
- Medium-Latitude VLF/ELF Emissions as Deduced from the Multi-Stationed Direction Finding Measurements
- Scattering of Electromagnetic Waves by Cylindrical Irregularity Immersed in a Plasma at Oblique Incidence
- ARRIVAL DIRECTION OF AURORAL HISS EMISSIONS DETERMINED BY TRIPARTITE OBSERVATION
- The wave distribution functions of plasmaspheric ELF hiss: GEOS 1 observation in the equatorial region
- An Observing Plan of Wave Normal Direction of Auroral VLF Emissions on Board a Rocket at Syawa Station
- Study of Auroral VLF Hiss Observed at Syowa Station, Antarctica
- Ray-tracing interpretation of wave normal directions of chorus emissions observed in the off-equatorial region of the outer magnetosphere
- On the Polarization of Half-Gyrofrequency Whistler-Mode Waves in the Two-Component Magnetospheric Plasma
- Nonlinear effect for the Omega signals in the auroral ionosphere by rocket observations
- Direction finding of half-gyrofrequency VLF emissions in the off-equatorial region of the magnetosphere
- The generation mechanism of ELF hiss in detached plasma regions of the magnetosphere, as based on the direction finding results
- Characteristics of substorm-associated VLF/ELF emissions at medium latitudes
- Low latitude aurorae on October 21, 1989. I.