Three‐Dimensional and Trans‐Hemispheric Changes in Ionospheric Electron Density Caused by the Great Solar Eclipse in North America on 21 August 2017

Abstract

AbstractWe report the three‐dimensional (3‐D) structure of the electron depletion caused by the great solar eclipse on 21 August 2017 derived from dense Global Navigation Satellite Systems (GNSS) total electron content observations. A linear least squares inversion was performed with a continuity constraint to stabilize the solution. The reconstructed 3‐D ionospheric electron density depletion showed a peak height at ~200 km. The depletion reached 42%, 60%, and 72%, below 250, 350, and 450 km, respectively, and the vertically integrated (150–450 km) decrease was 54%. We validated the accuracy of the electron density depletion at 200 km above the Millstone Hill observatory with the incoherent scatter radar observation and at 400 km using the in situ measurement by the Swarm satellite. The coincidence suggests that 3‐D tomography is useful for investigating the vertical structure of eclipse‐induced ionospheric changes. We further detected the electron depletion and enhancement with maximum values of 1.4–1.9 TECU and 0.7–1.0 TECU, respectively, in the geomagnetic conjugate region in the southern hemisphere.