A puzzling feature of the Earth’s equatorial upper atmosphere is the occurrence of enhanced VHF radar echoes near 150-km altitude. These so-called 150-km echoes have been observed for over 50-years, and occur nearly every day, making them a persistent feature of the equatorial ionosphere.
However, the source of the echoes remains unknown. We present observational and modeling results of the response of the 150-km echoes and ionosphere electron densities to a solar flare that occurred on September 7, 2005. Similar rapid descent during the solar flare, and gradual ascent following the flare is seen in both the observed 150-km echoes and simulated electron densities. This result provides evidence for the connection between structures in the 150-km echoes and background ionosphere electron densities, providing insight into the formation mechanism of the 150-km echoes.
Publication Name: Geophysical Research Letters
First HAO Author's Name: Nick Pedatella