Introduction

Trace and Traceo are ray tracing models written in GNU Fortran 77, designed to perform two-dimensional acoustic ray tracing in ocean waveguides with flat or variable boundaries (wavy surfaces, bottom upslopes or downslopes, sea mountains, canyons, etc.). Such boundaries can exhibit range dependent properties. The two models can also handle general sound speed profiles or sound speed fields. The receiver array can be horizontal, vertical, rectangular or it can have an arbitrary shape. At the user request both Trace and Traceo can provide different sets of output information, which can be either ``geometric'' (ray coordinates, travel time, amplitude, refraction and reflection coordinates, number of surface and bottom reflections, reflection coefficients, etc.), or ``physical'' (acoustic pressure, particle velocity or transmission loss). Traceo exceeds Trace capabilities by allowing to define a smooth object located between the source and the receiver array, providing a ray tracing tool which can be used in detection problems. The present document introduces the theory behind ray tracing calculations, the procedure to install the models, the general structure of input and output files, and some examples of the calculations performed with the current (``0.3th'') version of the models; at the end of the document the conclusions and future work will be presented.