Effects of ionosphere disturbances on low frequency propagation

Abstract

Results of vertical-incidence pulse observations at the Central Radio Propagation Laboratory, National Bureau of Standards, show that ionospheric storms have appreciable effects on the reflective properties of the E-region at night. Daytime effects of storms are limited primarily to periods of high absorption, coinciding with similar effects at higher frequencies. Data obtained at 160 kc indicate that the character of low frequency reflections at night may be a sensitive indication of storminess. Correlation is shown between magnetic K-indices and low frequency data. During storms, effects have been of such magnitude that they cannot be ignored in design of low-frequency navigational or high-speed communications systems.