DISTORTION OF TRIMPI SHAPES BY HIGH-ALTITUDE WINDS

Phase and amplitude perturbations (Trimpis) on man-made VLF signals pr opagating in the Earth-ionosphere waveguide, due to lightning-induced ionization occurring off the great circle path from VLF transmitter to receiver, are sensitive to the instantaneous lateral location of this ionization. High-altitude winds of similar to 100 m/s can move this i onization fast enough during its decay to change the rate, shape, and even sign of the phase and amplitude perturbation decays.