Echo‐sounding of the Kennelly‐Heaviside layer

Abstract

Observations of the Kennelly‐Heaviside layer have been continued at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington by the writer and L. R. Hafstad. The United States Naval Research Laboratory, as before, has kindly transmitted the necessary schedules of signals. Multivibrator‐modulation was used, giving very sharp pulse‐signals on 4,435 and 8,870 kilocycles. A marked diurnal‐variation in the effective height of the layer and in the echo‐pattern received for each transmitted pulse or “peak” was observed in three 24‐hour series of observations taken during the early fall and winter. The echo‐pattern shows multiplicities during the day and evening but becomes very complex at night. A few observations made during the magnetic disturbance of October 17 to 19, 1928, showed an unusually great effective height and a change in the echo‐pattern.