Altitudinal dependence of meteor radio afterglows measured via optical counterparts

TL;DR

This study combines radio and optical observations to analyze meteor radio afterglows, revealing a strong altitudinal cutoff around 90 km that impacts radio emission, likely due to wave damping from electron collisions.

Contribution

It provides the first comprehensive analysis of the altitudinal dependence of meteor radio afterglows using combined optical and radio data, identifying a critical altitude for radio emission.

Findings

Radio afterglows are absent below approximately 90 km altitude.

The altitudinal cutoff supports the hypothesis that wave damping affects radio emission.

Optical counterparts were observed for 44 radio afterglows.

Abstract

Utilizing the all-sky imaging capabilities of the LWA1 radio telescope along with a host of all-sky optical cameras, we have now observed 44 optical meteor counterparts to radio afterglows. Combining these observations we have determined the geographic positions of all 44 afterglows. Comparing the number of radio detections as a function of altitude above sea level to the number of expected bright meteors we find a strong altitudinal dependence characterized by a cutoff below $\sim$ 90 km, below which no radio emission occurs, despite the fact that many of the observed optical meteors penetrated well below this altitude. This cutoff suggests that wave damping from electron collisions is an important factor for the evolution of radio afterglows, which agrees with the hypothesis that the emission is the result of electron plasma wave emission.