Service, NOAA-National Ocean , 1998, North Carolina, Pamlico Sound Area, High-resolution Bathymetry: NOAA-National Ocean Service, Silver Spring, MD.This is part of the following larger work.Online Links:
Cross, VeeAnn A. , Bratton, John F. , Bergeron, Emile, Meunier, Jeff K. , Crusius, John, and Koopmans, Dirk, 2005, Continuous Resistivity Profiling Data from the Upper Neuse River Estuary, North Carolina, 2004-2005: Open-File Report 2005-1306, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 30.000000
Ordinates (y-coordinates) are specified to the nearest 30.000000
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
This dataset was acquired from the NOAA NOS Estuarine Bathymetry website: <http://spo.nos.noaa.gov:16080/bathy/>.
(301) 713-3000 (voice)
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peter.grose@noaa.gov
To provide high resolution bathymetry for the Pamlico Sound area in North Carolina.
NOAA National Ocean Service, 2000, Estuarine Bathymetry: National Oceanic and Atmospheric Administration, Silver Spring, MD.Online Links:
Null values (encoded -32767 within the DEMs) are used to represent all locations either above (outside) the local high water datum (the shoreline as defined by the National Ocean Service) or outside the extents of the estuary as delineated by the CAF.
Bathymetric elevations within these data sets are referenced to the local tidal datum which typically is Mean Lowest Low Water (MLLW) averaged over a 19 year tidal epoch. Elevations above this datum (between the datum and the shoreline) have positive values (meters to centimeter resolution) while those below are negative. Note that this datum is different from that used by USGS for land elevation data that it distributes in DEM form which are referenced to Mean Sea Level (MSL).
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
The accuracy of a DEM is dependent upon the level of detail of the source soundings and the grid spacing used to sample that source. The primary limiting factor for the level of detail of the source is the scale of the source survey, the technology used to collect soundings, and the resolution of the source soundings. Additional complications is describing accuracy are the ages of the surveys used to collect sounding in a given area. Care was used to use the most recent surveys covering a given area but in some instances adjacent surveys may be decades apart in age. In some regions, the only source data were at fathom (6 feet) resolution. In general, most source surveys were certified to one foot or better by the National Ocean Service.
The horizontal accuracy of the DEM is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the source soundings used to generate the DEM. As a first approximation the locational accuracy of the source soundings are 0.0015 m at source "Smooth Sheet" scale (120 m @ 1:80,000 to 15 m @ 1:10,000). Smooth Sheets are maps generated as a principle product of each (historic) hydrographic survey with fully corrected soundings plotted on them.
The vertical RMSE statistic is used to describe the vertical accuracy of a DEM. It encompasses both random and systematic errors introduced during production of the data. The RMSE is encoded in element number 5 of record C of the DEM. This accuracy estimate includes components related to quantization of the source soundings (1.3 to 0.15 m), the systematic editing of the source data (1% or 0.10m), un-sampled bathymetric features (estimated at less than 5% of depth), time related changes (erosion, deposition, and seismic shifts), and dredging operations (cut and fill).
It is estimated that the accuracy of the Bathymetric DEMs is 2% of depth or 1 meter for depths grater than 20 meters and 2 % of depth or 0.20 meters for depths shallower than 20 meters.
THESE DEMs SHOULD NOT BE USED FOR NAVIGATION.
There are three types of DEM vertical errors: blunder, systematic, and random. These errors are reduced in magnitude by editing but cannot be completely eliminated. Blunders are errors of major proportions and are easily identified and removed during interactive editing. Systematic errors follow some fixed pattern and are introduced by data collection procedures and systems. Systematic error artifacts include vertical unsampled elevation shifts, relative spacing of the source soundings, misinterpretation of terrain surface caused by softness or poor reflectivity and by the resolution of the collected soundings (feet, feet & fractions, fathoms, fathoms & fractions, meters, tenths of meters etc.). Random errors result from unknown or accidental causes. The 1 degree (DSQ) DEMs are generated from 30 m grids on UTM projection. The rms difference between these surfaces is an estimate of the vertical accuracy of the DSQ DEMs.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None.
- Use_Constraints: These data should not be used for navigation purposes.
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Downloadable Data
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(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov