Dataset Identification:
Resource Abstract:
- description: This data set includes sun-illuminated of the sea floor offshore of eastern Cape Cod, Massachusetts. The data
were collected with a multibeam sea floor mapping system during USGS survey 98015, conducted November 9 - 25, 1998. The surveys
were conducted using a Simrad EM 1000 multibeam echo sounder mounted aboard the Canadian Coast Guard vessel Frederick G. Creed.
This multibeam system utilizes 60 electronically aimed receive beams spaced at intervals of 2.5 degrees that insonify a strip
of sea floor up to 7.5 times the water depth (swath width of 100 to 200 m within the survey area). The horizontal resolution
of the beam on the sea floor is approximately 10% of the water depth. Vertical resolution is approximately 1 percent of the
water depth. The sun-illuminated topographic (shaded relief) image has a 4-m pixel size and was created by vertically exaggerating
the topography two times and then artificially illuminating the relief by a light source positioned 45 degrees above the horizon
from an azimuth of 0 degrees. In the resulting image, topographic features are enhanced by strong illumination on the northwestward-facing
slopes and by shadows cast on southeastern slopes. The image also accentuates small features (relief of a few meters) that
could not be effectively shown as contours alone at this scale. Unnatural-looking features or patterns oriented parallel or
perpendicular to survey tracklines are artifacts of data collection and environmental conditions. The data have a weak striping
that runs parallel to the ship's track. Some of the striping is the result of poor data return at nadir that appears
as evenly-spaced thin speckled lines. Some striping is also due to critical angle effects, where the intensity of return varies
as a function of the angle of incidence of the incoming sound on the seafloor (Hughes-Clark and others, 1997).; abstract:
This data set includes sun-illuminated of the sea floor offshore of eastern Cape Cod, Massachusetts. The data were collected
with a multibeam sea floor mapping system during USGS survey 98015, conducted November 9 - 25, 1998. The surveys were conducted
using a Simrad EM 1000 multibeam echo sounder mounted aboard the Canadian Coast Guard vessel Frederick G. Creed. This multibeam
system utilizes 60 electronically aimed receive beams spaced at intervals of 2.5 degrees that insonify a strip of sea floor
up to 7.5 times the water depth (swath width of 100 to 200 m within the survey area). The horizontal resolution of the beam
on the sea floor is approximately 10% of the water depth. Vertical resolution is approximately 1 percent of the water depth.
The sun-illuminated topographic (shaded relief) image has a 4-m pixel size and was created by vertically exaggerating the
topography two times and then artificially illuminating the relief by a light source positioned 45 degrees above the horizon
from an azimuth of 0 degrees. In the resulting image, topographic features are enhanced by strong illumination on the northwestward-facing
slopes and by shadows cast on southeastern slopes. The image also accentuates small features (relief of a few meters) that
could not be effectively shown as contours alone at this scale. Unnatural-looking features or patterns oriented parallel or
perpendicular to survey tracklines are artifacts of data collection and environmental conditions. The data have a weak striping
that runs parallel to the ship's track. Some of the striping is the result of poor data return at nadir that appears
as evenly-spaced thin speckled lines. Some striping is also due to critical angle effects, where the intensity of return varies
as a function of the angle of incidence of the incoming sound on the seafloor (Hughes-Clark and others, 1997).
Citation
- Title Image of the 4-m Sun-illuminated Topography of the Sea Floor off Eastern Cape Cod (CAPENORTHSUN_GEO4M_WGS84.TIF, Geographic,
WGS84).
-
- creation Date
2018-06-08T16:07:20.976217
Resource language:
Processing environment:
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Metadata data stamp:
2018-08-06T21:04:58Z
Resource Maintenance Information
- maintenance or update frequency:
- notes: This metadata record was generated by an xslt transformation from a dc metadata record; Transform by Stephen M. Richard, based
on a transform by Damian Ulbricht. Run on 2018-08-06T21:04:58Z
Metadata contact
-
pointOfContact
- organisation Name
CINERGI Metadata catalog
-
- Contact information
-
-
- Address
-
- electronic Mail Address cinergi@sdsc.edu
Metadata language
eng
Metadata character set encoding:
utf8
Metadata standard for this record:
ISO 19139 Geographic Information - Metadata - Implementation Specification
standard version:
2007
Metadata record identifier:
urn:dciso:metadataabout:c101d60f-d2a9-4f42-8a33-13a60ea2d5e5
Metadata record format is ISO19139 XML (MD_Metadata)