Figure 10From: How does ionospheric TEC vary if solar EUV irradiance continuously decreases?Seasonal variations of the cubic fitted GEC at four solar EUV irradiance levels. Levels 1, 2, 3, and 4 correspond to 0.1- to 50-nm EUV flux equal to 3, 2, 1, and 0.5 (in units of 1014 photons/m2/s), respectively. The parameter S equals the ratio of minimum GEC to maximum GEC.Back to article page