Office of Coast Survey
National Oceanic and Atmospheric Administration
U.S. Department of Commerce

Hydrodynamic Models

Simulating Complex Systems

Coast Survey develops and tests hydrodynamic modeling applications for use in operational systems and products. Three types of modeling applications are developed:

  • three-dimensional operational forecast systems (OFS) to support safe navigation mission requirements,
  • tide models and tidal datum products used in NOAA’s VDatum vertical datum transformation software, and
  • storm surge models to provide combined tide and storm-induced surge guidance for coastal water levels and inundation.

  • Coast Survey and the Center for Operational Oceanographic Products and Services (CO-OPS) have coordinated on the development and operational implementation of a system of real-time, operational coastal 3-D hydrodynamic models around the U.S. coastline for more than 15 years. These oceanographic prediction systems provide high resolution nowcasts (analyses) and forecast guidance of circulation in the coastal ocean, specifically coastal water levels and 3-D currents, temperatures, and salinity from 48 to 60 hours into the future. These coastal forecast modeling systems that OCS and CO-OPS have partnered to develop, maintain, and operate are called Operational Forecast Systems (OFS). The OFS are designed to meet marine transportation needs for environmental intelligence that support decision making for the safe transit of ships in coastal waters, as well as the needs of other users such as National Weather Service marine forecasters, fisheries, and coastal managers. The Regional Ocean Modeling System (ROMS) and the Finite Volume Community Ocean Model (FVCOM) are the primary models used for OFS model development. In addition, NOS partners with NOAA’s Great Lakes Environmental Research Laboratory to develop and test forecast modeling systems for the Great Lakes.

    The OFS applications of these models go through a rigorous development and validation process. The validated modeling system is then delivered to CO-OPS, who works with the National Weather Service’s National Centers for Environmental Prediction to install it for operations on NOAA’s Weather and Climate Operational Supercomputing System (WCOSS). The forecast systems are installed within the NOS Coastal Ocean Modeling Framework (COMF), a standardized suite of programs and formats that streamline operational management, and run at automatic intervals each day to generate forecast guidance. Currently the OFS cover numerous major ports along the U.S. coastline and over the Great Lakes, but coverage is not yet complete. In addition, OCS is investigating the use of data assimilation in the OFS to improve their initial depiction of the present state of the ocean conditions each day in order to improve the forecast guidance to users.

    Depiction of surface water currents from the Northern Gulf of Mexico Operational Forecast System.

  • In support of NOAA’s VDatum vertical datum transformation tool, Coast Survey develops numerical tide models and tidal datum products for U.S. coastal waters. VDatum is designed to vertically transform geospatial data among a variety of vertical datums. These transformations allow users to convert their data from different vertical references into a common system, thereby enabling the fusion of diverse geospatial data, particularly in coastal regions. The NOS VDatum team develops regional VDatum updates, specifically working on the tidal datum transformations that are made available in the VDatum software.

    The ADCIRC coastal hydrodynamic model simulates tides in regional applications, and these modeled water levels are subsequently used to compute spatially varying tidal datums. These model outputs are further combined with tidal observations so that the final VDatum vertical datum transformations are consistent with the published tidal datums made available by CO-OPS. Data assimilation techniques are used to blend the model- and observation-derived tidal datums, and this technique will also allow VDatum to provide an associated spatially varying uncertainty in the future.

    VDatum demonstration project in Tampa Bay, Florida.

  • Coast Survey has also developed forecast systems specifically for addressing coastal flooding. Coast Survey has applied the community-based hydrodynamic model ADCIRC to the prediction of storm surge and tides during tropical (i.e., hurricane) and extratropical (i.e., nor’easter) storms. These storm surge models are different from the traditional operational forecast systems in that they only predict water levels, but they also have been designed to address storm surge risks. They are a larger scale than traditional OFS to account for the uncertainty in storm tracks, extending across the East or West coasts. Recent advancements include the extension of these storm surge models over land to predict local flooding conditions.

    These NOS storm surge model applications have been coordinated within NOAA’s Storm Surge Roadmap and offer the advantage of advanced modeling physics in the suite of operational storm surge forecasting applications. Results from these models are used as guidance to forecasters and are also used to provide boundary conditions to other models such as the Nearshore Wave Prediction System. They are being evaluated for providing large-scale coastal water level predictions as input to the NWS National Water Model, and they are also being used to assess coastal flooding from landfalling hurricanes.

    Water level forecast guidance from the Extratropical Surge and Tide Operational Forecast Systems (ESTOFS).

Revised: 6/8/2018