Backscatter A [8101]--Drakes Bay and Vicinity, California

Metadata Updated: November 12, 2020

This part of DS 781 presents data for the acoustic-backscatter map of Drakes Bay and Vicinity, California. Backscatter data are provided as separate grids depending on mapping system or processing method. The raster data file is included in "BackscatterA_8101_DrakesBay.zip", which is accessible from https://pubs.usgs.gov/ds/781/DrakesBay/data_catalog_DrakesBay.html. These data accompany the pamphlet and map sheets of Watt, J.T., Dartnell, P., Golden, N.E., Greene, H.G., Erdey, M.D., Cochrane, G.R., Johnson, S.Y., Hartwell, S.R., Kvitek, R.G., Manson, M.W., Endris, C.A., Dieter, B.E., Sliter, R.W., Krigsman, L.M., Lowe, E.N., and Chin, J.L. (J.T. Watt and S.A. Cochran, eds.), 2015, California State Waters Map Series—Drakes Bay and Vicinity, California: U.S. Geological Survey Open-File Report 2015–1041, pamphlet 36 p., 10 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20151041. The acoustic-backscatter map of the Drakes Bay and Vicinity map area, California, was generated from backscatter collected by California State University, Monterey Bay (CSUMB), and by Fugro Pelagos. Mapping was completed between 2007 and 2010, using a combination of 200-kHz and 400-kHz Reson 7125, and 244-kHz Reson 8101 multibeam echosounders, as well as 468-kHz SEA SWATHPlus interferometric system. These mapping missions combined to collect backscatter data from about the 10-m isobath to beyond the 3-nautical-mile limit of California's State Waters. Within the acoustic-backscatter 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). These data are not intended for navigational purposes.

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 September 7, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2014 (publication)
Frequency Of Update asNeeded

Metadata Source

Harvested from DOI Open Data

Graphic Preview

Acoustic backscatter imagery of Drakes Bay and Vicinity map area

Additional Metadata

Resource Type Dataset
Metadata Date September 7, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2014 (publication)
Responsible Party U.S. Geological Survey, Pacific Coastal and Marine Science Center (Point of Contact)
Contact Email
Guid
Access Constraints Use Constraints: USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes., Access Constraints: none
Bbox East Long -122.76
Bbox North Lat 38.04
Bbox South Lat 37.88
Bbox West Long -122.97
Coupled Resource
Frequency Of Update asNeeded
Graphic Preview Description Acoustic backscatter imagery of Drakes Bay and Vicinity map area
Graphic Preview File http://pubs.usgs.gov/ds/781/DrakesBay/images/BackscatterA_8101_DrakesBay.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 2007-01-01
Temporal Extent End 2010-01-01

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