The Numerical Analysis of Two-Frequency Mutual Coherence Function for Infrared Laser Propagation in Clouds

The relations of the amplitudes and phases of the Γ for laser pulse propagation in clouds to ω_d are given by Ishimaru et al, based on average particles in clouds. In practice, since the particles size in clouds is according to a size distribution spectrum, the Γ ought to be derived from a particles size distribution. Based on the approximately solution which has been presented by Ishimaru and Hong, these examples of infrared laser pulse propagating in cloud are described and numerical analyses show the Γ's amplitude and phase obvious changes for tenuous and dense clouds. For a kind of cumulus and stratocumulus over Xi'an areas, considering cloud particles size distribution and mean particle size, respectively, the Γ's amplitudes and phases are calculated. These numerical results show that the differences between results calculated by applying particle size spectrum and mean size in clouds are remarkable, especially for the phase calculation. Therefore, It is shown that the Γ calculated according to particles size distribution is more reasonable than by average particle size. This study is important for us to improve infrared laser ranging and image systems performances and atmospheric remote-sensing techniques.