About this Book

In the Stanford Radio Acoustic Sounding System (RASS), an electromagnetic signal is made to scatter from a moving acoustic pulse train. Under a Bragg-scatter condition, maximum electromagnetic scattering occurs. The scattered radio signal contains temperature and wind information as a function of the acoustic pulse position. In this investigation, RASS performance is assessed in a real atmosphere where coherency of the acoustic pulse is degraded as it propagates vertically into the lower atmosphere. The only assumption made is that the electromagnetic wave is not affected by stochastic perturbations in the atmosphere. It is concluded that, for acoustic pulses with carrier frequencies below a few kilohertz propagating under typical atmospheric conditions, turbulence has little effect on the strength of the received radio signal at heights up to a few kilometers. This result implies that focusing of RF energy by the acoustic wavefronts is primarily a function of sound intensity which decreases as 1/x-squared, where x denotes altitude.