National ocean service partnership: DGPS-Supported hydrosurvey, water level measurement, and modeling of Galveston Bay




Schmalz Jr., Richard A.

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U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, Office of Ocean and Earth Sciences, Marine Analysis and Interpretation Division, Coastal and Estuarine Oceanography Branch


The National Ocean Service (NOS), as part of its Partnership Project Program, has performed a Differential Global Positioning System (DGPS) supported by hydrographic survey of Galveston Bay during June-July 1995. Tidal benchmark elevations with respect to the DGPS ellipsoid reference frame were determined using static DGPS at each of 10 shore-based tide gauges. The US Army Corps of Engineers obtained six-minute water level data using DGPS on a buoy outside the Entrance to Galveston Bay. These data were analyzed to determine harmonic constants and tidal datums. This report focuses on the development and application of a three dimensional circulation model for the Bay and near shelf using a limited observational data set (including water level, salinity, and temperature) for model calibration and validation. The model is based on the Princeton University ocean model code and has a sigma coordinate with five levels in the vertical and orthogonal curvilinear coordinates in the horizontal. The model equations are listed and the grid development is described. The model code has been modified to include spatially varying atmospheric pressure anomaly and wind field forcings as developed from Coastal-Marine Automated Network (C-MAN), National Data Buoy Center (NDBC) buoys, and National Weather Service (NWS) surface weather stations.


136 pgs.


differential global positioning system (DGPS), hydrographic surveys, water levels, salinity, temperature, tidal datum, modeling, meteorology, oceanography, sea level, mathematical model, measurement, simulation methods, hydrography, ocean circulation