Trace accuracy

The discussion presented in [4,5] and [2] share in common a calculation of transmission loss, with a ``canonical'' Munk profile (see Fig.1). Source frequency is considered to be 50 Hz, and the source is located at 1000 m. 51 rays were traced with the Trace model between -14$^\circ$ and 14$^\circ$, restricting the ray fan exclusively to waterborne rays (see Fig.12). The ray plot indicates the existence of three large shadow zones, two of them (10-50 km and 70-100 km) in the upper part of the waveguide and the other one (40-80 km) in the lower part of it.

Figure 12: Ray trace for the Munk profile.

Those rays were used to calculate a curve a transmission loss, for receiver at 800 m depth. The comparison of Trace with Kraken (see Fig.13) reveals a good agreement in the general trend of transmission loss calculated by both models. The differences in amplitude are negligible, except in the shadow zones, where rays contribute poorly to the field.

Figure 13: Transmission loss for the Munk profile for a receiver depth of 800 m using KRAKEN (solid) and TRACE (dash-point).