On the influence of the jet stream variations on infrasonic propagation

Abstract

The jet stream is an eastward flowing wind jet seen around 10 km with its largest magnitude in the winter months, lessening in the summer. Its direction, while predominantly easterly, can vary from northeast to southeast on a day-to-day basis. It can produce ducting of infrasonic signals when its speed is of sufficient magnitude. Infrasonic signals were observed on a network of sensor arrays from a series of explosions detonated throughout the year. Each series consisted of 3 explosions, 1 series for each season of the year. Sensors were deployed in arrays of 4 sensors per array. The network consisted of 4 lines of arrays extending in the westerly, easterly, northeasterly, and southeasterly directions. These arrays were located at distances ranging from 20 km to 80 km from the source. The data from each array was analyzed to determine if infrasonic signals from the explosions were detected. A propagation model was produced for each event using a parabolic equation and an atmospheric profile corresponding to the time of each event. Correlations between the observations and the direction of the jet stream are investigated.