Fig. 3From: Ionospheric responses on the 21 August 2017 solar eclipse by using three-dimensional GNSS tomographyThe electron density variations as well as the difference percentage at 1755 UT at 260 km altitude plane (a–b), 42oN latitude plane (c–d), and − 100oE longitude plane (e–f). The electron density difference in a, c, and e is calculated by Ned-Ned-1. The electron density difference percentage in b, d, and f is calculated by Eq. (4)Back to article page