Simulating acoustic scattering from atmospheric temperature fluctuations using a k-space method.

This paper describes a numerical method for simulating far-field scattering from small regions of inhomogeneous temperature fluctuations. Such scattering is of interest since it is the mechanism by which acoustic wind velocity profiling devices (Doppler SODAR) receive backscatter. The method may therefore be used to better understand the scattering mechanisms in operation and may eventually provide a numerical test-bed for developing improved SODAR signals and post-processing algorithms. The method combines an analytical incident sound model with a k-space model of the scattered sound close to the inhomogeneous region and a near-to-far-field transform to obtain far-field scattering patterns. Results from two test case atmospheres are presented: one with periodic temperature fluctuations with height and one with stochastic temperature fluctuations given by the Kolmogorov spectrum. Good agreement is seen with theoretically predicted far-field scattering and the implications for multi-frequency SODAR design are discussed.