bellhop raysolver differences / comparison

[apatlpo]

Not being an acoustician, it's difficult to grasp whether there are what are the differences between Bellhop and RaySolver physics. Do we expect any?

The documentation states they are similar albeit a 2D vs 2-1/2D difference which I do not understand and would be happy to read any references about.

I gave a try to a direct comparison in deep water with Munk sound speed profile. The full script is found here. I tried to align input parameters for both models but am not 100% sure this was done correctly.

My preliminary observations are that:

• transmission loss look about similar albeit for a blank with RaySolver
• rays are very different with many more more rays with Bellhop than with RaySolver
• (probably related) signal arrivals are also very different for both models

You'll find below several figures illustrating the results

Would anybody have ideas in order to explain differences or align results (if this has any sense) ?