Figure 2From: How does ionospheric TEC vary if solar EUV irradiance continuously decreases?The demonstrations of total electron content (TEC)-EUV regression fitting. Linear fitting for the data of EUV < 4 (a), quadratic fitting for the data of the full EUV range (b), and cubic fitting for the data of the full EUV range and constrained with the term of zero TEC at zero EUV (c).Back to article page