The Marine Modeling and Analysis Branch of NOAA’s Coast Survey Development Laboratory develops hydrodynamic models for numerous types of applications. These include three-dimensional models for realtime nowcast/forecast systems, depth-averaged tidal models used to compute tidal datums, and the linking of these models to ecological applications such as harmful algal bloom predictions.

All of these models vary in both time and space, and the output results can be linked to numerous geospatial applications. Examples of variables that are output from the model include water levels, currents, salinity and temperature. The changes in these variables over time and space can be shown visually for users, an example of which is shown below for water levels and currents from two operational nowcast/forecast models:

Model results can also be analyzed over time to reveal the average value of variables. For example, harmonic analysis of time series at each spatial location in a model can show the influence of specific tidal frequencies throughout a coastal region. Another example is examining water level time series to compute the average of the high and low water values, the results of which can be used to determine tidal datums such as mean higher high water (MHHW), mean high water (MHW), mean tide level (MTL), diurnal tidal level (DTL), mean lower water (MLW) and mean lower low water (MLLW).

These examples of geospatial information extracted from the models may then be integrated in software and GIS applications to serve specific user applications. The tidal datums, for example, are imported into the VDatum software for vertical datum transformations across a given geographic area. For more information on VDatum, click here.  The Coast Survey Development Laboratory is also examining the integration of such information into databases, making it publicly available as netCDF files on an OPeNDAP server, and evaluating formatting options to make the files more available to the GIS community.