What effect of the sun's activity influences ionospheric propagation on a daily basis?

The ionosphere is created and maintained primarily by the sun's electromagnetic radiation, especially ultraviolet and X-ray emissions, along with particle radiation. When these emissions strike the Earth's upper atmosphere, they ionize gas molecules, creating the electrically charged layers that refract radio waves. Because this ionization process is driven by constant daily sunlight exposure, the level of ionization naturally peaks during the day and decreases at night. While events like Coronal Mass Ejections (CMEs) or solar wind variations do impact propagation, they are intermittent events that cause geomagnetic storms rather than the normal, daily baseline ionospheric behavior.