ROCKET MEASUREMENTS OF AURORAL RADIO ABSORPTION

Abstract

Three Black Brant rockets were instrumented by the Radio Physics Laboratory of the Defence Research Board to measure ionospheric radio absorption during ionospheric disturbances. This instrumentation included v.h.f. receivers to measure the strength of cosmic radio noise and of radio signals from the ground during the flight. Geiger counters were provided by the National Research Council of Canada to measure the flux of energetic particles. Results from a flight made at dawn on October 28, 1960, during auroral absorption, indicate that most of the absorption at 22 Mc/s occurred at an altitude between 65 and 90 km, with the most intense absorption occurring in the 70- to 75-km region.This observation is consistent with the observation made by N.R.C. of increasing numbers of electrons with energies greater than 30 kev above about 74 km, both during the ascending and the descending portions of the flight. Assuming large horizontal extent of the absorbing regions, the rocket measurement of 11.5 db of total absorption at 22 Mc/s along an oblique path at 60° from the zenith agrees closely with the 30 Mc/s zenith riometer observation of 3.3 db.