The average is calculated in three steps to preserve the integrity of both the ground wave and the ionospheric reflection.
From the nature.com
Composition changes in the thermosphere can also alter ionospheric structures that affect radio wave propagation and communications.
From the sciencedaily.com
Finally, the average ground wave and the average ionospheric reflection are spliced together to make the final average waveform.
From the nature.com
Even though the L2 code data are encrypted, the signal's carrier wave enables correction of some ionospheric errors.
From the en.wikipedia.org
The critical frequency is the limiting frequency at or below which a radio wave is reflected by an ionospheric layer at vertical incidence.
From the en.wikipedia.org
Radio wave propagation is affected by atmospheric conditions, ionospheric absorption, and the presence of obstructions, for example mountains or trees.