Ionospheric Effects caused by Electrons precipitated from the Outer Radiation Belt

Abstract

DURING the period October 1962 to March 1963, there was a disturbance in the ionosphere at the Antarctic station Sanae (70° 18′ S., 2° 22′ W.) whenever a high flux of precipitated electrons was observed in the magnetically conjugate area by the satellite Alouette¹. Together with Gledhill, we² have shown that similar disturbances are produced at other stations lying near the same magnetic shell (L = 4) in both the northern and southern hemispheres. We established that flux values above a certain level are observed only when the ionosphere is disturbed, and that the percentage of total time for which this level is exceeded at each station is almost exactly the same as the percentage time for which the ionosphere is disturbed. Our results showed that the frequency of occurrence of ionospheric disturbances on L = 4 increases markedly in the vicinity of the South Atlantic geomagnetic anomaly. This observation was attributed to the fact that the mirror points of particles trapped in the outer radiation belt are much lower there than anywhere else, being responsible for the high intensities of charged particles observed there^3,4.