17:15 〜 18:45
[PEM12-P08] Horizontal structures and movements of sporadic E layers observed with ionosonde receiver networks
キーワード：スポラディックE層、電離圏、イオノゾンデ
The sporadic-E (Es) layers are high plasma density layers that appear suddenly in the E region of the ionosphere, around 100 km altitude. It is known that tidal winds play a major role in the formation and movement of Es. The horizontal movement of Es has been studied with various observational methods and numerical simulations. Continuous TEC observation is useful to capture the horizontal structure of Es because of its many observation sites, although Es height cannot be measured. Es height measurement is important because wind is critical to the motion of Es and the distribution of wind is dependent on height. The advantage of ionosonde observation is the ability to measure the height. There are four ionosonde facilities of NICT in Japan, and they perform vertical and oblique observation. However, the distance of ionosonde observation network is longer than typical Es scale, and the network does not have enough observation points to investigate horizontal movement of Es. In this study, we installed receivers and performed multistatic observations with networks of ionosonde and receivers to investigate the horizontal structure and movement of Es over Japan.
In the ionosonde observation networks, two receivers are installed at Aso and Miyazaki in June 2023. They receive HF waves transmitted from ionosonde of NICT Radio Observation Facilities at Wakkanai, Kokubunji, Yamagawa and Ogimi. Radio waves transmitted from ionosonde are reflected by Es layers above the midpoint between the ionosonde and the receiver, which measures the electron density of the Es above the midpoint. The horizontal scale of the Es layers can be estimated by determining whether the same Es layer is observed at multiple observation points based on the correlation between the density and altitude changes of Es. The movement of Es can be investigated in tristatic observation. The new receivers are near Yamagawa station, so we can perform a tristatic observation by comparing of the ionosonde vertical observation at Yamagawa and oblique observations at Aso and Miyazaki. The distance is 190 km between Yamagawa and Aso, and 100 km between Yamagawa and Miyazaki. In this tristatic observation, the direction and velocity of Es horizontal movement are calculated from the difference in observation time at each site.
This network will make simultaneous observation with sounding rocket experiment, RIDE campaign to be launched from JAXA Uchinoura Space Center in Kagoshima in the summer of 2024.
In this study, we will discuss the horizontal structure and horizontal movement of the Es layer with data from the ionosonde network.
In the ionosonde observation networks, two receivers are installed at Aso and Miyazaki in June 2023. They receive HF waves transmitted from ionosonde of NICT Radio Observation Facilities at Wakkanai, Kokubunji, Yamagawa and Ogimi. Radio waves transmitted from ionosonde are reflected by Es layers above the midpoint between the ionosonde and the receiver, which measures the electron density of the Es above the midpoint. The horizontal scale of the Es layers can be estimated by determining whether the same Es layer is observed at multiple observation points based on the correlation between the density and altitude changes of Es. The movement of Es can be investigated in tristatic observation. The new receivers are near Yamagawa station, so we can perform a tristatic observation by comparing of the ionosonde vertical observation at Yamagawa and oblique observations at Aso and Miyazaki. The distance is 190 km between Yamagawa and Aso, and 100 km between Yamagawa and Miyazaki. In this tristatic observation, the direction and velocity of Es horizontal movement are calculated from the difference in observation time at each site.
This network will make simultaneous observation with sounding rocket experiment, RIDE campaign to be launched from JAXA Uchinoura Space Center in Kagoshima in the summer of 2024.
In this study, we will discuss the horizontal structure and horizontal movement of the Es layer with data from the ionosonde network.