Radio Emissions from Earth’s Foreshock and Bolides

Abstract: It is well understood that Earth’s foreshock radiation is due to the bow shock deflecting the solar wind and accelerating electrons upstream into the foreshock where they produce Langmuir waves and radio emissions. Recently, the Long Wavelength Array (LWA) in the USA observed radio waves from meteors and other bolides entering the ionosphere and atmosphere. Here we correct and generalise the model for Earth’s foreshock radiation by Kuncic et al. (2004) and adapt it to the bolide case. We also produce the first 2D source pictures of Earth’s foreshock radiation, confirming the prediction from Gurnett et al. (1993) that the radio source should be elongated perpendicular to the plane containing the magnetic field vector. For the bolide case, we show that our predicted fluxes are in the same range as observations by Obenberger and Taylor (2018) and therefore the theory is now a viable explanation for radio emissions from fireballs.