Wave steepening in ionospheric total electron density due to the 21 August 2017 total solar eclipse

A data-adaptive method named Hilbert-Huang transform is employed to examine the nonlinear and non-stationary evolution of the waves. The results show that the TEC wave behaves as a traveling ionospheric disturbance before the totality appearance, turns later into steepening, and breaks eventually.

A TEC wave with a period of similar to 40 min and wavelength of similar to 1,000 km propagates mainly in an east-southward direction before the totality appearance. The wave amplitude and scales, respectively, increases and reduce by near similar to 50% as the moon shadow approaches the western coast of the continental United States. The short-period TEC waves (period similar to 2 min) reveal that the wave may break eventually when the wave gets steeper.