Backscatter B [7125]--Offshore Half Moon Bay, California

Metadata Updated: November 12, 2020

This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Half Moon Bay map area, California. Backscatter data are provided as two separate grids depending on mapping system (Reson 7125 and Reson 8101). The raster data file is included in "BackscatterB_7125_OffshoreHalfMoonBay.zip," which is accessible from http://pubs.usgs.gov/ds/781/OffshoreHalfMoonBay/data_catalog_OffshoreHalfMoonBay.html. The acoustic-backscatter map of the Offshore of Half Moon Bay, California was generated from backscatter data collected by Fugro Pelagos and by California State University, Monterey Bay (CSUMB). Mapping was completed in 2006 and 2007, using a combination of 400-kHz Reson 7125 and 244-kHz Reson 8101 multibeam echosounders. Within the final imagery, brighter tones indicate higher backscatter intensity, and darker tones indicate lower backscatter intensity. The intensity represents a complex interaction between the acoustic pulse and the seafloor, as well as characteristics within the shallow subsurface, providing a general indication of seafloor texture and composition. Backscatter intensity depends on the acoustic source level; the frequency used to image the seafloor; the grazing angle; the composition and character of the seafloor, including grain size, water content, bulk density, and seafloor roughness; and some biological cover. Harder and rougher bottom types such as rocky outcrops or coarse sediment typically return stronger intensities (high backscatter, lighter tones), whereas softer bottom types such as fine sediment return weaker intensities (low backscatter, darker tones).

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 April 26, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2013 (publication)
Frequency Of Update asNeeded

Metadata Source

Harvested from DOI Open Data

Additional Metadata

Resource Type Dataset
Metadata Date April 26, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2013 (publication)
Responsible Party U.S. Geological Survey, Pacific Coastal and Marine Science Center (Point of Contact)
Contact Email
Guid
Access Constraints Use Constraints: Please recognize the U.S. Geological Survey (USGS) and California State University, Monterey Bay, Seafloor Mapping Lab (CSUMB). USGS-authored or produced data and information are in the public domain. This information is not intended for navigational purposes. Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data. Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey. This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology., Access Constraints: None
Bbox East Long -122.39
Bbox North Lat 37.54
Bbox South Lat 37.38
Bbox West Long -122.60
Coupled Resource
Frequency Of Update asNeeded
Graphic Preview Description Acoustic backscatter imagery of offshore Half Moon Bay.
Graphic Preview File <http://pubs.usgs.gov/ds/781/OffshoreHalfMoonBay/images/BackscatterB_7125_OffshoreHalfMoonBay.jpg>
Graphic Preview Type JPEG
Licence Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 2006-01-01
Temporal Extent End 2007-01-01

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