Development of Two-Way Nesting in the Navy Coastal Ocean Model

We report the ongoing effort to implement and test two-way embedding schemes in the Navy Coastal Ocean Model (NCOM), which can run as a stand-alone ocean model, as well as a component within the Coupled Ocean/Atmospheric Mesoscale Prediction System (COAMPS). While COAMPS provides a framework for one- and two-way coupling among atmosphere, ocean, and wave models, embedded coupling between coastal and regional scale ocean models is needed to advance the operational capability across multi-scales in nearshore waters; in particular, in regions that are bathymetrically complex and strongly influenced by riverine, estuary, and wetland processes. We shall discuss the nesting strategy, results of implementing various schemes and boundary conditions at the grid interface, and issues associated with bathymetry inconsistency between the coarse and fine grids. Evaluations are based on idealized experiments and real coastal simulations with tides and atmospheric surface forcing. Needs for improvements are addressed.