Rocket-Induced Lower Ionosphere Disturbances Derived from Measurements of VLF Transmitter Signals

Rocket launch can induce large-scale atmospheric disturbances, which were mainly investigated using measurements of total electron content (TEC) in previous studies. In this study, we report the perturbations in Very-Low-Frequency (VLF) transmitter signals triggered by three rocket launch events, which, different from TEC measurements, are directly related to the D-region ionosphere. Although the rocket type, launch site, transmitting frequency, and receiver location were different, the perturbations in VLF measurements were similar in all three events. They typically occurred ~4–14 minutes after the liftoff, resulted in an amplitude change of up to 14 dB, and had a common period of ~3–7 minutes. Moreover, all perturbations consisted of two isolated pulses and this feature is notably different from previous measurements. The VLF amplitude change, in general, increases with the rocket weight and decreases with the distance from the launch site. Given the close correlation between rocket launch and VLF measurements, as well as the similarity between these events, these perturbations were likely caused by the shock acoustic waves generated during rocket launch since both the propagation speed and periods were similar.