The COHERENS model

COHERENS is a three-dimensional multi-purpose numerical model, designed for application in coastal and shelf seas, estuaries, lakes, reservoirs, ... The model is available as a free source code for the scientific community and can be considered as a tool for a better understanding of the physical and ecological processes and for the prediction and monitoring of waste material in shelf seas, the coastal zone and estuaries. Its ease of implementation across a range of computing platforms means that it is attractive to groups who have a sufficient modelling expertise and have need for sophisticated model products. Important advantages of the model are its transparency due to its modular structure and its flexibility because of the possibility to select different processes, specific schemes and different types of forcing for a particular application. The program structure allows users to perform process as well as predictive and operational setups without knowledge of the detailed model structure.

The first version of the program, now denoted as COHERENS V1 was developed over the period 1990-1998 by a multinational group, as part of the European projects PROFILE, NOMADS and COHERENS. Since its release in April 2001, more than 1400 registrations have been recorded on the COHERENS Web site.

Preparation for a full update of the program started in 2003 during the European projects ODON (2003-2005) and ECOOP (2007-2009). The code has been completely rewritten in FORTRAN 90 and can be used both in sequential and parallel mode using the MPI parallel communication library. Output can (optionally) be provided in portable netCDF format from within the program. Both curvilinear and general σ-coordinates are available for creation of model grids.

The program is now ready for release as a free software and is given the official name of COHERENS V2.0. Modules for biology, sediments and particle tracers are not yet implemented in the current version.

Several further updates with improvements and additional features have already been started and will be released in the near future. Current activities include the implementation of a generic biological model, a more extended sediment transport module which takes account of different size classes, a particle tracer module, structures for engineering applications in port structures and water ways, an implicit scheme which removes the mode splitting scheme, various inundation schemes, etc.