Atmospheric Gravity Waves in the Ionosphere and Thermosphere During the 2017 Solar Eclipse

Abstract

As a cavity of solar radiation created by the lunar shadow moves across the United States on 21 August 2017, decreases in local ionospheric and thermospheric (IT) temperature and density are anticipated. The average velocity of the total solar eclipse across the United States is ~700 m/s. The supersonically moving lunar shadow has induced bow waves and gravity waves that are observed by the Global Navigation Satellite System (GNSS) network. We use the Global Ionosphere-Thermosphere Model, a global circulation model solving for nonhydrostatic equations, with high-resolution (2° in longitude and 0.5° in latitude) and high-cadence (forcing updated every 2 s) settings to investigate the IT responses related to the atmospheric gravity wave perturbations during the solar eclipse. The modeled IT conditions extracted at 5-s cadence at two ground stations reveal different responses in both neutral and electron densities under totality and partial-eclipse scenarios. A bow wave of −0.2 TECu develops and lasts hours since totality, which is comparable with the GNSS observations. Gravity waves with period of 20–30 min observed by GNSS have been reproduced in our simulations.