NOAA's National Ocean Service (NOS) is developing an operational forecast system for the Northern Gulf of Mexico (NGOFS) using the finite-volume coastal ocean model FVCOM. In addition to providing the maritime navigation and emergency response communities with operational products of water levels, currents, water temperature, and salinity, the system will be the foundation for an emerging ecological forecasting capability for the northern Gulf of Mexico. Two periods of hindcast runs, (1) July 2008 – September 2009 and (2) November 2010-February 2011, respectively, were conducted to support the NGOFS development. This study describes the model set up and results from the hindcast runs.

The NGOFS covers a model domain along the Northern Gulf of Mexico coastal shelf from South Padre, TX (west) to Panama City, FL (east). It is bounded roughly by the 200-m isobath along the shelf break (south). The model grid is composed of 90,267 nodes and 174,474 triangular elements. The resolution varies from approximately 150 m near the coast to 11 km close to the continental shelf break. The hindcast runs are driven by net heat fluxes and winds at the surface, tidal and nontidal water level, velocity, and temperature and salinity transports along the open ocean boundary, and river discharges along the coast. Nontidal open ocean forcing is imposed from two regional models: NOS' Gulf of Mexico (NGOM) model for period (1) and the global Navy Coastal Ocean Model (NCOM) for period (2). Both these models are POM-based.

The hindcast results for both fields and time series of parameters such as water level, current velocity, temperature and salinity are recorded. Skill assessment is conducted through comparing the time series with observations for both periods. The assessment focuses on the following phenomena: water stratification;, river plume extensions; heat and salinity transports from the deep ocean onto the shelf and from the shelf into coastal embayments; spatial patterns and intensity of coastal currents; and the partition of contributions from barotropic and baroclinic components. In addition, we also investigate seasonal variations of the above parameters and the impacts due to the surface forcing, river discharge, and open ocean boundary conditions. In addition to the eventual operational implementation of NGOFS for this region, this study will help to gain some insight into the circulation system in the Northern Gulf of Mexico region.