INVESTIGATION OF THE DRIFTS OF THE EFFECTIVE POINT OF RADIO REFLECTION ALONG A METEOR TRAIN

Abstract

The concept of the effective point of radio reflection from a meteor train has been given on the basis of atmospheric turbulence, on a vertical scale of the order of 100 m to 6 km, in the M region. Some experimental evidence has been provided to support the postulate of its drifting along the train, using meteoric body doppler radar records, taken on 30.02 Mc/s at South Gloucester, during the Geminid shower periods of 1948–50. The velocities (Vs) of the above drifts in the case of 90 observations have been calculated, using the ranges of the observed meteors as obtained from the range–time records taken simultaneously on pulsed radar on 32.7 Mc/s at the Metcalfe Road field station (7.5 km distant). It is found that these velocities tend to have higher values in the case of shorter echo durations and vice versa. Theoretical interpretation of the observed results has been attempted. Reasonable assumptions of the ionization distribution along a meteor train and of diffusion rates at different levels in the M region have been made to derive the echo durations from different portions of a meteor train. Variation of these echo durations with position on the train has been taken into account to calculate the theoretical curves of vertical components of Vs vs. total echo durations, in the case of a Geminid shower. The effect of turbulence on echo durations has been taken into account to explain the observed results successfully.