Lightning Flash Counts and Radio Noise Fields in the Tropics

Abstract

IT is now generally accepted that the source of atmospheric radio noise is the natural lightning discharge associated with thunderstorms, the discharges possessing energy components throughout the radio-frequency spectrum¹. It is, therefore, to be expected that a correlation exists between the measured level of noise fields and the frequency of occurrence of lightning discharges in a given area. A standard lightning flash counter has been adopted by the International Radio Consultative Committee (C.C.I.R.) for obtaining statistical data about lightning flashes at various locations throughout the world². The Central Radio Propagation Laboratories of the United States (C.R.P.L.) and the Radio Research Board of the Department of Scientific and Industrial Research of Great Britain (D.S.I.R.) have designed two separate equipments for the measurement of atmospheric noise-levels, and these have been installed at chosen sites over the world. Fortunately, a standard lightning flash counter and one each of the noise recording equipments were kindly made available at Ibadan, Nigeria (7° 26′ N, 3° 54′ E.), in the tropical belt during and after the International Geophysical Year, thus facilitating the collection of a fairly large amount of statistical data for lightning flash counts and median values of noise power.