BackscatterB [Swath]--Offshore of Salt Point Map Area, California
Dataset Identification:
Resource Abstract:
This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Salt Point map area, California. Backscatter
data are provided as separate grids depending on mapping system or processing method. The raster data files are included in
"BackscatterSwath_SaltPoint.zip", which are accessible from http://pubs.usgs.gov/ds/781/OffshoreSaltPoint/data_catalog_OffshoreSaltPoint.html.
The acoustic-backscatter map of the Offshore of Salt Point map area, California, was generated from backscatter data 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 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.
Citation
Title BackscatterB [Swath]--Offshore of Salt Point Map Area, California
These data are intended for science researchers, students, policy makers, and the general public. These data can be used with
geographic information systems or other software to identify seafloor features.
thumbnail file description:
Acoustic backscatter imagery of the Offshore of Salt Point map area.
Resource language:
eng; USA
Resource progress code:
completed
Resource Maintenance Information
maintenance or update frequency:
asNeeded
Constraints on resource usage:
Constraints
Use limitation statement:
These databases, identified as acoustic-backscatter maps of Offshore Salt Point map area, California have been approved for
release and publication by the U.S. Geological Survey (USGS). Although these databases have been subjected to rigorous review
and are 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 these data have been processed successfully on a computer system at 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. The USGS
or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein.
Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise
does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
These data are not intended for navigational use.
Constraints on resource usage:
Legal Constraints
use constraint:
otherRestrictions
Other constraints
Use Constraints: This information is not intended for navigational purposes. 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. USGS-authored or produced data and information are in the public domain. Acknowledge the U.S.
Geological Survey and California State University, Monterey Bay, Seafloor Mapping Lab in products derived from these data.
Share data products developed using these data with the U.S. Geological Survey. 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. 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.
Constraints on resource usage:
Legal Constraints
Access Constraints
otherRestrictions
Other constraints
Access Constraints: If physical samples or materials are available, constraints on their on-site access are described in "WR
CMG Sample Distribution Policy" at URL: http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html
Spatial representation type code:
grid
Resource extent
Geographic Extent
Geographic Bounding Box
westBoundLongitude
-123.48
eastBoundLongitude
-123.28
northBoundLatitude
38.64
southBoundLatitude
38.48
Temporal Extent
2007-01-01
2010-01-01
Additional information on resource:
None
point of contact
-
pointOfContact
individual Name Peter Dartnell
organisation Name
U.S. Geological Survey, Pacific Coastal and Marine Science Center
position Name Physical Scientist
Contact information
Telephone
Voice (831) 460-7415
Fax (831) 427-4709
Address
400 Natural Bridges Dr., Santa Cruz, CA, 95060-5792
Country USA
name Of Measure Horizontal Positional Accuracy Report
evaluation Method Description
Horizontal_Positional_Accuracy_Report: Estimated to be no less than 2 m, owing to water depth and total propagated uncertainties
of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data
processing that includes sounding cleaning, gridding, and datum transformations.
AbsoluteExternalPositionalAccuracy
name Of Measure Vertical Positional Accuracy Report
notes: This metadata was automatically generated from the Content Standard for Digital Geospatial Metadata ("CSDGM version 2") standard
(version FGDC-STD-001-1998) using the 2012-06-20T17:21:00 version of the FGDC RSE to ISO 19115-2 transform.
notes: Last Metadata Review Date: 2014-01-01
Metadata contact
-
pointOfContact
individual Name Peter Dartnell
organisation Name
U.S. Geological Survey, Pacific Coastal and Marine Science Center
position Name Physical Scientist
Contact information
Telephone
Voice (831) 460-7415
Fax (831) 427-4709
Address
400 Natural Bridges Dr., Santa Cruz, CA, 95060-5792
Country USA