Range dependent effect on ray propagation in the North Eastern Atlantic

Getting oceanographic data on a large scale and with sufficient time and space resolution is generally very difficult. However, these data are essential when studying with accuracy the propagation of sound, especially when simple analytic models are not available due to the complexity of the ocean variability at the required distance and time scale. This is for example the case of oceanic acoustic tomography (OAT) in the North Eastern Atlantic (study area of the French national program POMME). In OAT, the classical stratified assumption has to be checked against realistic simulations of long range wave propagation. For the North Eastern Atlantic where the Mediterranean mid waters and the mixed upper layer induce complex effects on temperature profiles, numerical models tend to be more and more accurate. This is the case for the CLIPPER model developed by the LEGI(*) in Grenoble. The authors show in this work how this set of high resolution and realistic numerical data can be used to simulate the acoustic wave propagation with new insights. They focus their analysis to the POMME area: [-15 W, -22 W] longitudes, [35 N, 48 N] latitudes. They first describe the numerical oceanographic data as given by the CLIPPER model and show their high resolution quality. They present then the results of systematic ray tracing calculations that has been made between pairs of transmitter and receiver (receiver is a long-line vertical array) in the North-South direction