Atmospheric and Oceanographic Analyses and Forecasts for the Chesapeake Bay Region during the Coastal Marine Demonstration Project

The National Oceanographic Partnership Program-supported Coastal Marine Demonstration Project for the greater Chesapeake Bay region and contiguous U.S. east coastal domain had two demonstrations in June - July 1999 and February - April 2000. Out of a suite of experimental and operational marine products that were being demonstrated to the marine user community, a number of atmospheric and oceanographic model-based products were focused on the bay. The Chesapeake Bay system comprised the eXperimental Estuary Forecast Center (XEFC) established in the Coast Survey Development Laboratory in partnership with the Air Resources Laboratory. This system included high resolution (4 km) analyzed and forecast winds, and nowcasts and forecasts of water levels, waves and currents. The system of models began with the analyzed and forecast atmospheric fields derived from the operational 32-km Eta model for North America, which are used for initialization, first guess fields, or boundary conditions for the Bay models. The hourly analyzed surface atmospheric fields (surface winds, temperature, and pressure) are derived from the Local Analysis and Prediction System, as customized for application in the Chesapeake Bay (called CBLAPS), and which is based on a suite of surface and upper air operational observations. The twice daily 36-h forecast fields (3-D winds, wind stress, temperature, pressure, humidity, heat fluxes, and visibility) are derived from the Regional Atmospheric Model System as applied in the Chesapeake Bay region (called CBRAMS). Both the analyzed and forecast winds were used to drive three different bay models: (1) a barotropic hydrodynamic model for producing hourly analyses and 24-h forecasts of water levels twice a day; (2) a wind-wave model for producing hourly analyses and 24-h forecasts of wind-waves twice a day; and (3) a 3-dimensional hydrodynamic model for producing twice daily 24-h forecasts of currents. The hydrodynamic models were also forced at their open ocean boundaries by observed water level gauge data and forecast water level from a coastal ocean model for the nowcast and forecast, respectively. All fields were produced on a pseudo-operational schedule for the purposes of the demonstration and were displayed on a web site (and provided in digital GRIB form) for evaluation and use by a wide variety of users. The XEFC will be described and assessments derived from both technical verification and the marine community user evaluation during the two demonstrations will be provided.