A summary diagram of electron density variations due to G(., Fχ). Panel a shows the G(.) function representing electron density below 100 km altitude (black solid line) that is set by a combination of a logarithmic function (red dotted line), a power function (blue dotted line), and a linear function (green dotted line) passing through two points: the origin and the electron density value at 100 km altitude calculated using GAIA. Panel b shows the time variation of Fχ associated with the flare. Panel c is the electron density variation created by combining the function G(.) set in panel a and the ionization altitude corresponding to Fχ in panel b. The black dotted line is the electron density calculated using GAIA. The solid lines of cyan, magenta, and yellow in panel c are the functions G(., Fχ), which correspond to the points shown in panel b.