Model of the Position of the Main Ionospheric Trough in the Eccentric Dipole Coordinates

Based on the data of probe measurements of the electron density in the ionosphere on the CHAMP satellite from July 2000 to December 2007, an analysis of the possibility of using the coordinates of the eccentric dipole (ED) in the model for the invariant latitude of the minimum of the main ionospheric trough, Φ, was carried out. It has been established that the Φ model constructed from these data in the coordinates of the corrected geomagnetic (CGM) latitude can be used without changes in the ED coordinates, since the standard deviation of the model is less than the difference in the Φ values for these two options for specifying geomagnetic latitudes. The difference in the Φ values for these two options is minimal for the Southern Hemisphere and can be noticeable for the Northern Hemisphere, especially at the longitudes of the East Siberian Magnetic Anomaly. The dependence of Φ on local time and geomagnetic activity is the main one. The dependence of Φ on geographic longitude is relatively weak, therefore the difference in the Φ values between the CGM and ED coordinates even at the longitudes of the East Siberian Magnetic Anomaly is less than the standard deviation of the model.