Global distribution of atmospheric radio noise derived from distribution of lightning activity

Based on global maps of thunderstorm activity observed by the Ionosphere Sounding Satellite-b, atmospheric radio noise levels over the world were calculated and global distribution maps of atmospheric radio noise were made for frequencies of 2.5, 5, 10, and 20 MHz for every four hours in universal time during autumn. The calculation method is discussed, including its treatmment of the characteristics of atmospherics, the occurrence rate of lightning discharges, and the propagation characteristics and power available from a local thunderstorm. The calculated results agree better with worldwide measurements than those given by CCIR Report No. 322. The characteristics of atmospheric radio noise, including the frequency dependence and geographical characteristics, are discussed and explained by the presented method.