Improving Tides of Operational Forecast System

Abstract:

Operational Forecast System (OFS) is the backbone of the operational coastal ocean weather forecast system in the National Ocean Service (NOS), National Oceanic and Atmospheric Administration (NOAA). Every day, OFSs provide 4 days forecasts of water level, currents, temperature and salinity in US coastal and estuarine waters where the model covers. Of all dynamic processes of a hydrodynamic model, tides probably is the most important dynamic process. In OFS’ development process, validation against the tides from tides only model run is usually the first step towards an operational hydrodynamic model which includes all air-sea interaction and forcing. Here we try to surmise the methodologies applied to hydrodynamic model development to improve the tidal simulation of a hydrodynamic model. Tidal simulation in a hydrodynamic model usually forced by the predicted tides and tidal currents prescribed at open boundary and tidal forcing derived from astronomical tidal potential. There are also internal processes that affect the tides for example bottom friction and internal tidal energy dissipation. Physical setting of a hydrodynamic model, like bathymetry and vertical reference system, is also important. Using different test cases, we demonstrated methodologies to improve the tides of a hydrodynamic model. Finally, we will present a data assimilation method that uses the observed tides to improve the tides of an OFS and a hydrodynamic model in general.