Figure 3

The TEC values at the zero solar EUV point. The left column is the TEC extrapolated from the linear TEC-EUV fitting for which the data of EUV < 4 were used (see Figure 2a), and the right column is the TEC extrapolated from the quadratic TEC-EUV fitting for which the data of the full EUV range were used (see Figure 2b). The white lines denote the dip equator, and the black contours denote zero TEC.