A Long-Term Survey of the Role of Atmospheric Planetary Waves in the Day-to-Day Variability of the Ionosphere

Atmospheric planetary waves play an important role in shaping how the ionosphere is coupled to the rest of the Earth's atmosphere. Of significant interest in this study are the 2-, 3-, and 6-day planetary waves. Using multiple long-term datasets, we performed an extensive survey of these wave events in the atmosphere and ionosphere. Our results show that 3-day (80%) and 6-day (92%) oscillations in the ionosphere observed from the ground have a known driver that originated mostly from a planetary wave, but 2-day oscillations often do not. While some of the 2- and 3-day ionospheric oscillations are associated with random fluctuations from the sun or magnetosphere, almost none of the 6-day oscillations in the ionosphere are associated with these external drivers. For the 2-day oscillations, there is a significant change in the correspondence between the ionospheric oscillation and known drivers during solstices (69%) compared to equinoxes (36%). The impact of the external drivers on 2-day oscillations in the ionosphere during equinoxes is ∼2 times larger than during solstices. When generating a corresponding response in the ionosphere, the strength of the amplitudes of 2-day westward wavenumber-3 planetary waves made a clear impact, but less clear for 3-day eastward 1 and 6-day eastward/westward planetary waves, revealing that wave amplitude is significant for driving ionospheric response. There is a likelihood of a 3-day eastward 1/6-day eastward planetary wave event generating a corresponding response in the ionosphere to be more when the solar activity conditions are low compared to when it is high.