The KRAKEN Normal Mode Program
NAVAL RESEARCH LAB WASHINGTON DC
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In the late 1970s several normal-mode models existed which were widely used for predicting acoustic transmission-loss in the ocean however, each had its own problems. Typical difficulties included numerical instabilities for certain types of sound-speed profiles and failures to compute a complete set of ocean modes. In short, there was a need for a model that was robust, accurate, and efficient. In order to resolve these problems a new algorithm was developed forming the basis for the KRAKEN normal mode model. Over subsequent years, KRAKEN was greatly extended, with options for modeling ocean environments that are range-independent, range-dependent or fully 3-dimensional. The current version offers a specialist a vast number of options for treating ocean-acoustics problems or more generally acousto-elastic waveguides. On the other hand, it is easy for a less sophisticated user to learn the small subset of tools needed for the common problem of transmission-loss modeling in range-independent ocean environments. This report addresses the need for a more complete users guide to supplement the on-line help files. The first chapters give a fairly technical description of the mathematical and numerical basis of the model. Additional chapters give a simpler description of its use and installation in a manner that is accessible to less scientifically-oriented readers.
- Computer Programming and Software