Theoretical Modelling of Chromospheric Emission Lines Through The Solar Activity Cycles 21–23 According To The Observational Analysis Results

In our previous papers, we compared the connection between the sizes of faculae and plage regions, sunspots/sunspot groups (SGs), chromospheric emission lines and solar spectral irradiance variability between the spectral ranges 121.5–300.5 nm for the period 1981–2009 and discussed the changes in the sunspot counts (SSCs) and the number of SGs relative to the variations in solar activity indices. In this work, we tried to explain the theoretical reason for these variabilities in the ultraviolet region and connected these changes to the temporal variations of solar activity indices in comparison to different type of SSCs/SGs for the first time in the literature. We found that the intensity of Fe II (298.5 nm) ion in the last solar minimum was higher than the two previous solar minima 21 and 22. So, the velocity of particles of Fe II ions increases with decreasing density of the medium and increasing plage surface. Increasing velocity causes an increase in the acceleration and intensity of particles.