Meteor trail induced backscatter in MST radar echoes

Abstract

The amplitude variations and Doppler spectra of the 50 MHz radar echoes from meteor trails are investigated. The radar echoes from underdense meteor trails particulary during nighttime do not always fit the conventional specular reflection model. The echo was found to spread, sometimes, over as large as 8–10 km in range. In each range bin, the spread echo from the trail is produced with an altitude dependent time delay after the passage of the meteoroid producing the ionized trail. The Doppler spectra of the spread echo in each range bin is asymmetric with a high frequency wing comprised of narrow spectral peaks and successive spectral peaks amplitude decrease with frequency. These observations are interpreted as due to multiple reflections of the radar pulse between the striations generated parallel to the geomagnetic field along the length of the meteor trail. There is evidence to show that within the dynamo region the EW and NS components of the currents at lower and higher altitudes could be in opposite directions during the early morning hours of Sq electric field reversal.