Lunar Tide Effects on Ionospheric Solar Eclipse Signatures: The August 21, 2017 Event as an Example

Jann Yenq Liu, Tsung Yu Wu, Yang Yi Sun, Nicholas M. Pedatella, Chi Yen Lin, Loren C. Chang, Yi Chung Chiu, Chien Hung Lin, Chia Hung Chen, Fu Yuan Chang, I. Te Lee, Chi Kuang Chao, Andrzej Krankowski

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The ionospheric total electron content (TEC) derived from dense ground-based Global Navigation Satellite System receivers over the continental United States and those from global ionosphere maps are utilized to find the ionosphere response to the August 21, 2017 total solar eclipse. Maximum obscurations and their associated TEC major depressions appear simultaneously at midlatitudes, while major depressions elongate toward the magnetic equator with some delays in the equatorial ionization anomaly (EIA) region. The former is due to the photochemical loss process, while the latter is caused by the plasma transport of E×B drifts and lunar gravitation forces. TECs of predawn reductions, morning enhancements, afternoon reductions, and nighttime enhancements reveal that the semidiurnal lunar tide are essential. Since a solar eclipse always occurs on a new moon day, the lunar tide results in the early EIA appearance and major depressions being underestimated/diminished before and overestimated/enhanced after about 14:00 local time.

Original languageEnglish
Article numbere2020JA028472
JournalJournal of Geophysical Research: Space Physics
Issue number12
StatePublished - Dec 2020


  • equatorial ionization anomaly
  • lunar tide
  • solar eclipse


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