How is the T index calculated from ionosonde data?
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The T index, which characterizes the degree of disturbance in the ionosphere, is calculated using ionosonde data by analyzing the F2-layer critical frequency (foF2) observations. This involves filling in missing foF2 values by cloning data from another station and normalizing the peak density (NmF2) to its median value. The correlation between the cloned and observed foF2 values is crucial for accurate calculations, especially during ionospheric disturbances. The T index is determined based on the hourly deviation of NmF2 from the median, creating a logarithmic scale where different values represent varying levels of ionospheric disturbance, from quiet states to extreme conditions. This method allows for the identification and cataloging of ionospheric disturbances, with stormy conditions being more prevalent at high latitudes, during nighttime, and in equinox and winter seasons.
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| Papers (5) | Insight |
|---|---|
| The T index is derived from ionosonde data by reconstructing missed foF2 observations through cloning from another station and calculating the logarithmic deviation from a quiet reference value. | |
Open access 01 Dec 2017 | The T index is calculated using the change in Angle of Arrival (AoA) elevation angle, change in ionosonde virtual height, distance between transmitter and receiver, and ionosonde virtual height. |
| The T index is calculated from ionosonde data by integrating electron density up to 20,000 km using optimized Chapman or NeQuick topside formulations, reducing initial errors by 23-27%. | |
| Not addressed in the paper. | |
05 Sep 2020 | Not addressed in the paper. |
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