| Buzzards Bay, MA (M010) Bathymetric Digital Elevation Model (30 meter resolution)
Derived From Source Hydrographic Survey Soundings Collected by NOAA |
| Bathymetry for Buzzards Bay was derived from twenty-two surveys containing 220,615
soundings. Eight older, less accurate, overlapping surveys were omitted, and the overlap
from six older, less accurate surveys was omitted before tinning. The average separation
between the soundings was 54 meters. There were five surveys in the southwest that
dated from 1934 to 1939. The remaining seventeen surveys dated from 1954 to 1992.
The total range of sounding data was 2.3 meters to - 44.6 meters at mean low water.
Mean high water values between 0.8 and 1.9 meters were assigned to the shoreline.
Thirteen points were found that were not consistent with the surrounding data. These
were removed prior to tinning. DEM grid values outside the shoreline (on land) were
assigned null values (-32676). Buzzards Bay has fourteen 7.5 minute DEMs and two one
degree DEMs. 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. |
|