Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 30, 639-659, 2012
http://www.ann-geophys.net/30/639/2012/
doi:10.5194/angeo-30-639-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
Regular paper
02 Apr 2012
A meteor head echo analysis algorithm for the lower VHF band
J. Kero1,2, C. Szasz1, T. Nakamura1, T. Terasawa3, H. Miyamoto4, and K. Nishimura1 1National Institute of Polar Research (NIPR), 10-3 Midoricho, Tachikawa, 190-8518 Tokyo, Japan
2Umeå University, Box 812, 981 28 Kiruna, Sweden
3Institute for Cosmic Ray Research, Univ. of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa city, 277-8582 Chiba, Japan
4Department of Earth Science and Astronomy, College of Arts and Sciences, Univ. of Tokyo, Komaba 3-8-1, Meguro-ku, 153-8902 Tokyo, Japan
Abstract. We have developed an automated analysis scheme for meteor head echo observations by the 46.5 MHz Middle and Upper atmosphere (MU) radar near Shigaraki, Japan (34.85° N, 136.10° E). The analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters as well as investigations of the meteoroid-atmosphere interaction processes. In this paper we present this analysis procedure in detail. The algorithms use a combination of single-pulse-Doppler, time-of-flight and pulse-to-pulse phase correlation measurements to determine the radial velocity to within a few tens of metres per second with 3.12 ms time resolution. Equivalently, the precision improvement is at least a factor of 20 compared to previous single-pulse measurements. Such a precision reveals that the deceleration increases significantly during the intense part of a meteoroid's ablation process in the atmosphere. From each received pulse, the target range is determined to within a few tens of meters, or the order of a few hundredths of the 900 m long range gates. This is achieved by transmitting a 13-bit Barker code oversampled by a factor of two at reception and using a novel range interpolation technique. The meteoroid velocity vector is determined from the estimated radial velocity by carefully taking the location of the meteor target and the angle from its trajectory to the radar beam into account. The latter is determined from target range and bore axis offset. We have identified and solved the signal processing issue giving rise to the peculiar signature in signal to noise ratio plots reported by Galindo et al. (2011), and show how to use the range interpolation technique to differentiate the effect of signal processing from physical processes.

Citation: Kero, J., Szasz, C., Nakamura, T., Terasawa, T., Miyamoto, H., and Nishimura, K.: A meteor head echo analysis algorithm for the lower VHF band, Ann. Geophys., 30, 639-659, doi:10.5194/angeo-30-639-2012, 2012.
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