Development of a Hierarchy of Nested Models to Study the California Current System

The Naval Research Laboratory has developed a hierarchy of differing resolution data assimilating models in the Pacific Ocean, which includes global models, regional U.S. West Coast models, and high resolution coastal models such as for the Monterey Bay area. The three regional U. S. West Coast models (from 30°N to 49°N), designed to study the California Current System, are based on the Princeton Ocean Model (POM), the Navy Coastal Ocean Model (NCOM), called NCOM-CCS, and the Hybrid Coordinate Ocean Model (HYCOM), respectively. The NCOM-CCS formulation is a parallel version model capable of running reliably on many computer platforms. The model has nesting capabilities and offers the choice of using the sigma or a hybrid (sigma-z) vertical coordinate. The NCOM-CCS model also includes a coupled ecosystem model based on Chai et al., 2002. A variety of scientific issues related to model initialization, forcing, open boundary conditions, and model spin up are discussed. The focus of this paper is on: the sensitivity of the horizontal resolution of atmospheric forcing on the NCOM-CCS model predictive skills; the impact of open boundary conditions and coupling with global models on reproducing major hydrographic conditions in the California Current System; and the analysis of the model mixed layer predictions and data assimilation issues. Qualitative and quantitative comparisons are made between observations and model predictions for October 2000 – December of 2001 period.