Eastern thunderstorms located by VLF atmospherics parameters

Daily variations of spectral atmospherics parameters, as measured by the atmospheric analyzer of the Heinrich Hertz Institut in Berlin-Charlottenburg, are analyzed over an eight-day period for long lasting storm centers within the octant NE-E (receiving station Stockert near Bonn). The delay-time difference and the amplitude ratio of spectral groups at 6 and 8 kHz were measured alternatively every 5 min. Within the first-mode approximation these parameters are proportional to the propagation distance. Storm centers located by these parameter measurements are compared with synoptical observations. As theory indicates, the strong directional dependence of the GDD (group delay-time difference) and the SAR (spectral amplitude ratio) on the propagation direction relative to the earth's magnetic field is verified by these measurements.