Longitudinal variations of the ionospheric, plasmaspheric, and total electron contents in December 2009

The major morphological features of the global structure and longitudinal variations of the electron content distribution in the ionosphere–protonosphere system during the winter solstice for the solar activity minimum in 2009 are examined. It is demonstrated how the Weddell Sea anomaly and the longitudinal structure of the main ionospheric trough (depression in the concentration of light ions) manifest themselves through the total, ionospheric, and protonospheric electron contents. Based on model calculations, the specific features of longitudinal variations in the O⁺/H⁺ transition altitude are for the first time considered, which made it possible to estimate the altitude of the transition boundary from the ionosphere to the plasmasphere (protonosphere) for the selected conditions.