Empirical model of the global response of foF2 to changing geomagnetic activity
Abstract
An empirical model is developed, providing the relative deviation of foF2 from its monthly median value as a function of local time and Kp, to the global scale. The distribution of the relative deviation along the local time at any fixed moment is considered as composed of a diurnal and a semidiurnal waves, expressed by five parameters: daily mean (average offset), diurnal and semidiurnal amplitudes and their respective phases. The model expression is scaled by a modified function of Kp, which reflects the delayed reaction of foF2 to Kp changes. The model parameters are obtained by using data from 55 world-wide distributed ionosonde stations, having at least 11 years of continuous data. Data from each station was grouped into 12-month bins, every bin containing all available hourly data within the respective month of the year. The model parameters are obtained for each station/month bin by fitting the model expression to the data. By using station coordinates, global maps for each model-parameter/month are produced and their values are tabulated in grid files. The set of all 5 model parameters allows to obtain, through the model expression, the monthly average relative deviation of foF2 for any location on the globe. The model expression is then scaled by a mo dified function of Kp to represent the actual geomagnetic conditions. This model can be used directly in IRI to account for the short-term deviations of foF2, invoked by changing geomagnetic activity.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E..80K