Infrasonic atmospheric propagation studies using a 3-D ray trace model

Computer simulations of atmospheric infrasound propagation for severe weather environments allow us to more fully interpret infrasonic measurements from the ISNet. For example, we show that Gaussian vertical wind jets near 2 Km can effectively trap acoustic energy downwind and cause rays to be directed upward for upwind propagation. Infrasound from a fire just south of Denver near the time of a sounding is compared with the ray trace results. With no wind and a standard atmosphere robust propagation exists from a vertically extended sound source out to 20 Km. Isothermal layers and inversions provide an effective waveguide, trapping rays near the earth’s surface. Rays passing directly through a mesocyclone will be bent, while rays in other directions will not have azimuths affected. We are building up model initialization tools that can be used to simulate more complex storm environment effects on propagation.