It has long been predicted since 1970 that the Moon's shadow during solar eclipses - or rather the cooling region, sweeping over the Earth's atmosphere with a supersonic speed during solar eclipses - could trigger bow waves in the atmosphere. Thsi .

The longest total solar eclipse within next hundred years occurred on 22 July 2009 sweped over the Eastern Asia region during the noontime period.

An analysis of the Hilbert-Huang transform (HHT) was applied to study ionospheric TEC (total electron content) derived from ground-based GPS receivers in Taiwan and Japan.  Researcher not only found the feature of the predicted bow wave, but also a stern wave on the equator side of the eclipse path, as well as the stern wake right behind the Moon's shadow boat.

These bow- and stern waves are formed by acoustic gravity waves of periods about 3 and/or 5 minutes traveling equatorward with a phase speed of about 100 m/s in the ionosphere.

Source: Geophysical Research Letters