High-altitude radar meteors detected using a new analysis algorithm for interferometric meteor head echoes

We have a long-term goal of creating a holistic and cross-disciplinary approach to meteor research where we connect together topics such as meteor measurements, ablation simulations, meteoroid stream simulations, and sensor simulations. Here, we present the most recent work on developing an automated radar data analysis algorithm able to calculate probability distributions of meteor- and meteoroid parameters for head echoes measured using interferometric high-power large-aperture radars. The algorithm utilizes direct Monte Carlo simulations of uncertainties, with Bayesian Markov-chain Monte Carlo estimation of meteor model parameters. The algorithm also employs N-body propagation of distributions to perform orbit determination, estimating the galactic background noise temperature for absolute-calibration and an statistical approach using many high signal-to-noise ratio meteors for phase calibration. This analysis algorithm has been applied to data from the Middle and Upper atmosphere (MU) radar in Shigaraki, Japan. As a first case study, we have re-analysed a part of the MU radar meteor head echo data set collected during 2009-2010. As a result we have confirmed the existence of a rare high-altitude radar meteor population with initial altitudes reaching up to ~150 km. Out of the total amount of 106 000 events, only 74 had an initial altitude >130 km, while four of those had an initial altitude >145 km.