Ionospheric Total Electron Content Response to the Great American Solar Eclipse of 21 August 2017

Using a comprehensive database of ~4,000 ground-based Global Navigation Satellite Systems stations, we investigate the ionosphere's response to the 21 August 2017 solar eclipse. The high-resolution, two-dimensional maps of the ionospheric total electron content (TEC) were constructed using combined GPS and GLONASS measurements. Solar eclipse resulted in a continent-size TEC decrease with stronger effects up to 50% over the U.S. eastern coast. Along the totality path within an area of 75% obscuration TEC decreased by ~30–40%. We reveal a latitudinal dependence of the TEC response with equatorward expansion of TEC depletion. Recovery signature in the form of large-scale TEC enhancement up to 20–30% occurred in posteclipse period. Swarm and DMSP satellites encountered the eclipse-induced plasma density depletion and posteclipse increase at 450 km height and above. These effects were associated with downward plasma fluxes from topside ionosphere/plasmasphere and thermospheric changes.