4-m Image of the Northern Half of the Backscatter Intensity Mosaic of the Sea Floor off Northeastern Cape Cod from USGS Cruise 98015 (CAPENORTHMOS_GEO4M_WGS84.TIF, Geographic, WGS84)

Metadata Updated: November 12, 2020

This data set includes backscatter intensity of the sea floor offshore of northern 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. With backscatter intensity, the intensity of the acoustic return from the sea floor from the multibeam system, is a function of the properties of the surficial sediments and of the bottom roughness. Generally, a strong return (light gray tones) is associated with rock or coarse-grained sediment, and a weak return (dark gray tones) with fine-grained sediments. However, the micro-topography, such as ripples, burrows, and benthic populations also affect the reflectivity of the sea floor. Direct observations, using bottom photography or video, and surface samples, are needed to verify interpretations of the backscatter intensity data. The backscatter 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).

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Date November 25, 2019
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2006 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from DOI Open Data

Graphic Preview

Thumbnail image showing the extent and coverage of the data layer.

Additional Metadata

Resource Type Dataset
Metadata Date November 25, 2019
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2006 (publication)
Responsible Party U.S. Geological Survey (Point of Contact)
Contact Email
Guid
Access Constraints Use Constraints: Public domain data are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information., Access Constraints: None
Bbox East Long -69.828333
Bbox North Lat 42.116667
Bbox South Lat 41.966667
Bbox West Long -70.307833
Coupled Resource
Frequency Of Update notPlanned
Graphic Preview Description Thumbnail image showing the extent and coverage of the data layer.
Graphic Preview File http://pubs.usgs.gov/of/2005/1048/data/backscatter/mosaic/geo/capenorthmos_geo4m_wgs84-thumb.gif
Graphic Preview Type GIF
Licence Although all data have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1998-11-09
Temporal Extent End 1998-11-25

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