Second Generation CBEFS2

A second generation Chesapeake Bay Experimental Forecast System (CBEFS2) is under development to (i) improve water level forecasts from the existing two-dimensional model, (ii) provide three-dimensional flow-fields such as currents, temperature, salinity, etc. and (iii) prepare for ecosystem modeling and forecasting. The CBEFS2 is being developed based on the three-dimensional, Regional Ocean Modeling System (ROMS) flow code from Rutgers University. The ecosystem component of the system will provide predictions of the distribution of several Harmful Algal Bloom (HAB) species in Chesapeake Bay patterned on the currently employed sea nettles prediction system. The ROMS prediction system for Chesapeake Bay (CHESROMS) uses a curvilinear, orthogonal model grid with 150 x 100 points in the horizontal and 30 terrain-following sigma vertical levels (Figure 1).

Figure 1. ROMS model grid for CHESROMS application.

The initial conditions for the first model run consist of quasi-analytical, linearly scaled temperature and salinity fields (and a spin-up from rest). Subsequent runs are initialized from flow-fields saved in ROMS restart files. For validation testing the model forcings are: (a) astronomical tides from ADCIRC East Coast 2001 tidal database harmonics, (b) non-tidal water levels from the National Water Level Observation Network Duck, NC station, (c) open boundary temperature and salinity from the World Ocean Atlas (WOA) 2001 climatological database, (d) surface forcing from North American Regional Re-analysis (NARR) products and (e) rivers from US Geological Survey (USGS). The vertical eddy-viscosity parameterization is obtained through the k-Ω General Length Scale (GLS) turbulence model.

Some preliminary results for an axial temperature transect, surface salinity and surface current fields are shown in Figures 2-4.

Figure 2. Axial transect of the temperature in Chesapeake Bay

Figure 3. Surface Salinity in Chesapeake Bay

Figure 4 Velocity magnitude vectors in Chesapeake Bay.

After validation and calibration of the above modeling system against measured data, it will be run in a real-time, operational mode under the Coastal Ocean Modeling Framework (COMF) currently implemented at the Marine Modeling and Analysis Programs (MMAP/Coast Survey Development Laboratory/Office of Coast Survey/NOS) and the Center for Operational Oceanographic Products and Services (CO-OPS) at NOAA.

The model will be run daily, where in order to created the model inputs, COMF will fetch: (i) water level data from Duck, NC and extract its non-tidal component, (ii) river discharges from USGS and (iii) surface forcing data from a source such as the North American Mesoscale (NAM) model.