Effect of vertical drifts on the nocturnal ionization of the lower ionosphere

Abstract

Effect of vertical ionic drift velocities on the night-time ionization density in the lower ionosphere for heights ranging between 80 km to 130 km is studied by a method of successive approximation. Values are also given of the effective recombination coefficient as a function of height and time for these drift velocities. Velocities ranging from 1 to 20 km/hr are used. The resultant ionization profiles for velocities 1–5 km/hr represent magnetically quiet conditions, while those for higher velocities would represent disturbed conditions of increasing severity. It will be noted that the ionization density decreases for upward drift and increases for downward drift. The present work provides a quantitative explanation of the sudden cessation of night-time echoes of low-frequency radio waves at times of magnetic disturbances, such as those observed at the Pennsylvania State University (Lindquist, 1953).