Atmospheric Gravity Waves in the Ionosphere and Thermosphere During the 2017 Solar Eclipse. Issue 11 (5th June 2018)

• Record Type: Journal Article
• Authors: Lin, Cissi Y.; Deng, Yue; Ridley, Aaron
• Is Part Of: Geophysical research letters. Volume 45:Issue 11(2018)
• Page Start: 5246
• Page End: 5252
• Publication Date: 2018-06-05
• Subjects: solar eclipse -- gravity waves -- bow waves; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2018GL077388
• Languages: English
• ISSNs: 0094-8276

Abstract

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. Plain Language Summary: Just as a boat moving through the surface of a lake stirs up waves in its wake, the lunar shadow moving across continents stirs up waves in our atmosphere during a solar eclipse. While the 2017 solar eclipse allowed a once‐in‐a‐lifetime viewing opportunity for over 200 million Americans, it also allowed scientists to capture unambiguous bow waves predicted by theoretical studies decades ago with the modern Global Navigation Satellite System. In this study, we use a self‐consistent global circulation model for the upper atmosphere to further confirm the formation of bow waves by the supersonically moving lunar shadow. Waves with period of 20–30 min observed by Global Navigation Satellite System have been reproduced in our simulations. Key Points: Supersonically moving lunar shadow induces mesoscale waves at totality locations A bow wave front led by the lunar shadow is formed with modification of the in situ forcing VTEC have strong wave responses with periods of 20‐30 min