Ionosphere Storm Effects in the E Layer

Abstract

DURING the course of an ionosphere storm, and more particularly near its beginning, I have frequently observed that the signals from short-wave stations which are situated within the skip-zone are subject to a form of distortion which is peculiar to them alone. This is quite different from the 'flutter' and other types of fading to which signals from more distant stations often become subject during an ionosphere storm, and it takes the form of a partially rhythmic note of low audio-frequency, producing the effect of a distinct and pronounced 'rumble' upon the received signal. The intensity of the 'rumble' varies directly with the wave-length of the received station, and also, apparently, directly with its power and the directivity of its aerial system. It is particularly noticeable in Britain upon the signals from the B.B.C.'s high-powered short-wave stations. I have observed this effect to begin very early in an ionosphere storm, the signals from stations within the skip-zone often being affected in this way before those from more distant stations begin to show any signs of deterioration due to the storm.