Demonstration of a nowcast/forecast system for Galveston Bay




Schmalz RAJ

Journal Title

Journal ISSN

Volume Title



The National Oceanic and Atmospheric Administration installed a Physical Oceanographic Real Time System (PORTS) in June 1996 in Galveston Bay. Water surface elevation, currents at prediction depth (4.6m below MLLW) as well as near-surface and near-bottom temperature and salinity, and meteorological information are available at six-minute intervals. To complement the PORTS a nowcast/forecast system was initially developed over the Bay using a modified version of the Blumberg-Mellor (1987) three-dimensional hydrodynamic model. The Bay model was used to provide boundary conditions for a one-way coupled, fine resolution Houston Ship Channel model (Schmalz, 1998a). The nowcast component has recently been revised to work directly from the PORTS universal flat file format (PUFFF) files rather than from the PORTS data screen. During the forecast, the National Weather Service's Aviation Atmospheric and Extratropical Storm Surge Forecast Models are used to provide the meteorological and Gulf of Mexico subtidal water level forcings, respectively. The results are presented for a one-month demonstration period, 9 April through 9 May 1999, during which daily 24-hour nowcasts and 36-hour forecasts were performed using both bay and channel models in a pseudo-operational setting. The nowcast and forecast are separately evaluated for water levels, currents, salinity, and temperature. Evaluations of forecast Gulf of Mexico subtidal water level, freshwater inflows, and wind and sea level atmospheric pressure are also considered. Results are summarized and contrasted with a previous one-month evaluation during September 1997 (Schmalz, 1998c). To seek improvement, a pseudo-operational test-bed was developed and several tests performed. An assessment of improvement is made over the first week of June 1999. Finally, plans for additional demonstration periods and system developments are discussed




Atmospheric pressure, Atmospheric temperature, Flow of water, Hydrodynamics, Mathematical models, Meteorology, Ocean currents, Oceanography, Real time systems, Salinity measurement, Societies and institutions, Surface waters, Three dimensional, Water, Water levels