Meteor radar rates and the solar cycle

Abstract

A WORLDWIDE increase in meteor echo rates in 1963 was observed in New Zealand¹, Canada and Sweden and has been widely discussed in the literature^2–8. From radar observations in 1953–66 I reported⁹ a long term variation in the echo count rate with a peak occurring in 1963 near the solar minimum. Those observations also showed that the height of first appearance of meteors from a given shower had remained nearly constant at ∼ 110 km, whereas the average endpoint height had risen by ∼ 11 km from 1956 to 1963. It was thus evident that the 1963 peak in the meteor echo count rate was of atmospheric origin. We report here further observations, and propose that the phenomenon can be explained by a solar controlled variation of the atmospheric density gradient at the meteor ablation level, probably caused by a variation in the solar X-ray flux.