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  • Recorded tracings of high-frequency (HF) radio pulses reflected in the ionosphere. This ionograms are produced by an ionosonde at Wakkanai, Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The profile of the ionospheric plasma density can be obtained from this data.

  • Some parameters which are manually scaled from ionosondes obtained at Wakkanai station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are manually scaled basically every 1 hour. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are automatically scaled from ionosondes obtained at Kokubunji station in Tokyo, Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are automatically scaled basically every 15 minutes. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Recorded tracings of high-frequency (HF) radio pulses reflected in the ionosphere. This ionograms are produced by an ionosonde at Okinawa, Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The profile of the ionospheric plasma density can be obtained from this data.

  • Some parameters which are automatically scaled from ionosondes obtained at Wakkanai station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are automatically scaled basically every 15 minutes. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are manually scaled from ionosondes obtained at Okinawa station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are manually scaled basically every 1 hour. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are automatically scaled from ionosondes obtained at Yamagawa station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are automatically scaled basically every 15 minutes. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are manually scaled from ionosondes obtained at Kokubunji station in Tokyo, Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are manually scaled basically every 1 hour. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are manually scaled from ionosondes obtained at Yamagawa station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are manually scaled basically every 1 hour. Time is Japanese Standard Time (JST), which is UTC + 9.

  • Some parameters which are automatically scaled from ionosondes obtained at Okinawa station in Japan. The ionosonde sweeps HF radio pulses from 1MHz to 30MHz, basically every 15 minutes. The transmitted radio pulses travel more slowly within the ionosphere, depending on the ionospheric plasma density. The apparent height, that is, virtual height of the reflection point is recorded for each frequency of the transmitted HF radio wave in ionograms. When the frequencies become higher than the maximum plasma frequency of the ionospheric layer, the radio wave pass through the layer and be lost in space. The frequency which corresponds to the maximum plasma frequency of each layer is called critical frequency. Some parameters such as critical frequency (e.g., foF2, foEs) and virtual heights (h’F2, h’Es) are automatically scaled basically every 15 minutes. Time is Japanese Standard Time (JST), which is UTC + 9.