On the derivation of an hourly local index to define the normal ionosphere
In this paper an hourly local ionospheric index f n F 2 is proposed to define the normal level of the undisturbed ionosphere. For the determination of this index a model is developed where the normal values of the f 0 F 2 parameter were reproduced using multiple regression analysis. For eac...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
2000-06-01
|
| Series: | Annals of Geophysics |
| Subjects: | |
| Online Access: | http://www.annalsofgeophysics.eu/index.php/annals/article/view/3629 |
| Summary: | In this paper an hourly local ionospheric index f n F 2 is proposed to define the normal level of the undisturbed ionosphere. For the determination of this index a model is developed where the normal values of the f 0 F 2 parameter were reproduced using multiple regression analysis. For each month of the year, for a given station, a set of 48 or 72 coefficients are calculated, depending on the monthly sunspot activity. Then, the normal values of the f 0 F 2 parameter are computed as a function of the daily sunspot number. The analysis of the model results revealed the following characteristics for the f n F 2 index: first, the temporal variations that characterize the normal ionosphere, imposing some artificial effects on the monthly median values, are eliminated from the newly derived f n F 2 index. Second, the f n F 2 index does not follow the false steplike variations observed in the monthly median f 0 F 2 time series, in transition periods from one month to another. Third, during intervals of low magnetospheric activity,the f n F 2 index presents a very good degree of fit with the observed f 0 F 2 parameter, compared to the monthly median f 0 F 2 behaviour. During disturbed conditions, the f n F 2 index remains at the normal level, whereas median values are affected by ionospheric disturbances. In general, the data analysis showed that the f n F 2 index varies only with the daily sunspot number Rz and is independent of the magnetospheric activity, approaching the level of the normal ionosphere with a high degree of confidence. |
|---|---|
| ISSN: | 1593-5213 2037-416X |