Coupling time domain acoustical and mesoscale meteorological models

14th Long Range Sound Propagation Symposium, ANNAPOLIS, ETATS-UNIS, 17-/03/2011 - 18/03/2011In this paper, a coupling approach between a meso-scale meteorological model (Meso-NH) and an acoustic propagation model (TLM) is proposed. Meso-NH (http://mesonh.aero.obs-mip.fr/mesonh/) is the non-hydrostatic mesoscale atmospheric model of the French research community. It intended to be applicable to all scales ranging from large (synoptic) scales to small scales (Large-Eddy Simulation) and its performance for several boundary layer regimes has been tested successfully. In order to use it for acoustic purposes, very fine scale simulations have been carried out to be compared to the Lannemezan 2005 experiment, from which both acoustics and meteorological data are available. It was found necessary to take into account the drag force of tree instead of the classical roughness length approach. This development, and its validation, has been done and finally involves a good agreement between simulation and experiment. The Transmission-Line Matrix (TLM) is a time domain acoustics model which permits to take into account all the principle phenomenon of outdoor acoustic propagation (absorption, diffraction, reflection, refraction,..). Its validation has been first carried out for an homogeneous atmosphere (ground effects, obstacle effects, etc.). Next recent developments have been done to take into account meteorological effects through the effective sound celerity. Those new TLM predictions in inhomogeneous atmosphere are compared with FDTD simulations. Finally, the coupling between Meso-NH and the TLM model is presented. Thus, some comparisons between acoustics measurements and 3D simulations within the framework of Lannemezan-2005 experiment site are presented and discussed