Is the Relation Between Ionospheric Parameters and Solar Proxies Stable?
Abstract
The relationship between ionospheric parameters and solar activity proxies is important for long‐term studies as ionospheric climatology or long‐term trends and for modeling. It has been broadly assumed that this relationship is stable with time. Using foF2 and foE of four European stations with long (1976–2014) data series, Juliusruh, Pruhonice, Rome, and Slough/Chilton, we show that it is not quite correct assumption. The dependence of yearly average values of ionospheric parameters on solar activity proxies appears to be steeper in 1996–2014 than in 1976–1995 for foF2 and steeper after 2000 for foE. Also, the relationships among solar activity proxies seem to change. Yearly values of foF2 and foE are very predominantly controlled by solar activity represented by proxies.
Plain Language Summary
The ionosphere is created by solar ionizing radiation. However, its continuous measurements for long‐term studies of the ionosphere are not available; therefore, we use various proxies of solar activity. It has been broadly assumed that the relationship between ionospheric parameters and solar activity proxies is stable with time. Here we show that this is not the case. This relationship changed since the beginning of the 21st century. This should be taken into account in studies of ionospheric climatology and long‐term trends and in ionospheric modeling.
