Mats Bentsen, Nansen Environmental and Remote Sensing Center, Bergen
Incremental remapping was recently introduced as a transport/advection algorithm. The method solves the transport equations in conservation form and, in the context of layered ocean modelling, it ensures monotonicity of layer thickness for a non-divergent velocity field. Monotonicity is ensured for associated tracers for any velocity field that does not violate the CFL condition of the method. Adding tracers leads to a small incremental computational cost, since the method is geometrical in nature and many computations can be reused. These features make incremental remapping interesting for layered ocean modelling, especially taking into account the increasing interest in earth system modelling where the ocean component must deal with a large number of tracers. The traditional incremental remapping algorithm is naturally suited for B-grid models. Methods for implementing incremental remapping for C-grid models will be discussed. Solving transport equations for temperature and salinity within a layer with some reference density, typically introduces numerical density errors. A method for reducing this error using incremental remapping will be discussed. MICOM has been modified so that incremental remapping could be implemented. Results from this effort will be shown.