| St. Andrew Bay, FL (G110) Bathymetric Digital Elevation Model (30 meter resolution)
Derived From Source Hydrographic Survey Soundings Collected by NOAA |
| Bathymetry for St. Andrew Bay was derived from eleven surveys containing 93,025 soundings.
Seven overlapping, older, less accurate surveys were omitted entirely. Two older surveys
had overlapping portions deleted for the same reasons. The average separation between
soundings was 52 meters. One survey in the north dated from 1935; the rest dated from
1983 to 1988. The range of soundings for the eleven surveys was 2.9 meters to -19.0
meters at mean low water. Mean high water values of 0.4 or 0.5 meters were assigned
to the shoreline. Twenty-one points were found that were not consistent with the surrounding
points. These were removed prior to tinning. DEM grid values outside the shoreline
(on land) were assigned null values (-32676). St. Andrew Bay has nine 7.5 minute DEMs
and a single one degree DEM. The 1 degree DEMs were generated from the higher resolution
7.5 minute DEMs which covered the estuary. A Digital Elevation Model (DEM) contains
a series of elevations ordered from south to north with the order of the columns from
west to east. The DEM is formatted as one ASCII header record (A- record), followed
by a series of profile records (B- records) each of which include a short B-record
header followed by a series of ASCII integer elevations (typically in units of 1 centimeter)
per each profile. The last physical record of the DEM is an accuracy record (C-record).
The 7.5-minute DEM (30- by 30-m data spacing) is cast on the Universal Transverse
Mercator (UTM) projection. It provides coverage in 7.5- by 7.5-minute blocks. Each
product provides the same coverage as a standard USGS 7.5-minute quadrangle but the
DEM contains over edge data. Coverage is available for many estuaries of the contiguous
United States but is not complete. |
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