BackscatterA [8210]--Offshore of Salt Point Map Area, California

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Peter Dartnell
Originator: Rikk G. Kvitek
Publication_Date: 2014
Title:
BackscatterA [8210]--Offshore of Salt Point Map Area, California
Edition: 1.0
Geospatial_Data_Presentation_Form: GeoTiff

Larger_Work_Citation:
Citation_Information:
Originator: Samuel Y. Johnson
Originator: Peter Dartnell
Originator: Nadine E. Golden
Originator: Stephen R. Hartwell
Originator: H. Gary Greene
Originator: Mercedes D. Erdey
Originator: Guy R. Cochrane
Originator: Rikk G. Kvitek
Originator: Michael W. Manson
Originator: Charles A. Endris
Originator: Bryan E. Dieter
Originator: Janet T. Watt
Originator: Lisa M. Krigsman
Originator: Ray W. Sliter
Originator: Erik N. Lowe
Originator: John L. Chin
Publication_Date: 2015
Title:
California State Waters Map Series--Offshore of Salt Point map area, California
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Open-File Report
Issue_Identification: OFR 2015-1098
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://pubs.usgs.gov/of/2015/1098/>

Larger_Work_Citation:
Citation_Information:
Originator: Nadine E. Golden
Publication_Date: 2013
Title: California State Waters Map Series Data Catalog
Geospatial_Data_Presentation_Form: database
Series_Information:
Series_Name: Data Series
Issue_Identification: DS 781
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://pubs.usgs.gov/ds/781/>

Description:
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 "BackscatterA_8101_OffshoreSaltPoint.zip", which are accessible from <https://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.

Purpose:
To expand geologic mapping to the seafloor within the California's State Waters, to update coastal geologic mapping, and to contribute to a uniform regional geologic database, which can be used geographic information systems. Additionally, to provide a geologic map for the public and geoscience community to aid in assessments and mitigation of geologic hazards in the Point Reyes coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore. This information is not intended for navigational purposes.

Supplemental_Information: None

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2007
Ending_Date: 2010
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -123.48
East_Bounding_Coordinate: -123.28
North_Bounding_Coordinate: 38.64
South_Bounding_Coordinate: 38.48
Keywords:
Theme:
Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)
Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Bathymetry
Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Seafloor Topography
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Theme_Keyword: environment
Theme_Keyword: oceans
Theme_Keyword: imageryBaseMapsEarthCover
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: Seafloor Character
Theme_Keyword: Fisheries
Theme_Keyword: Ecosystem
Theme_Keyword: Multibeam
Theme_Keyword: Geology
Theme_Keyword: Bathymetry
Theme_Keyword: Backscatter
Theme_Keyword: Intensity
Theme_Keyword: Ocean Floor Topography
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Pacific Coastal and Marine Science Center
Theme_Keyword: CMGP
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Pacific Ocean
Place_Keyword: State of California
Place_Keyword: Northern California
Place_Keyword: Salt Point
Place_Keyword: Sonoma County


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>
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.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Peter Dartnell
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Position: Physical Scientist
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Dr.
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: USA
Contact_Voice_Telephone: (831) 460-7415
Contact_Facsimile_Telephone: (831) 427-4709
Contact_Electronic_Mail_Address: pdartnell@usgs.gov

Browse_Graphic:
Browse_Graphic_File_Name:
<https://pubs.usgs.gov/ds/781/OffshoreSaltPoint/images/BackscatterA_8101_OffshoreSaltPoint.jpg>
Browse_Graphic_File_Description:
Acoustic backscatter imagery of the Offshore of Salt Point map area.
Browse_Graphic_File_Type: JPEG

Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report: Not applicable for raster data.
Logical_Consistency_Report: Unspecified
Completeness_Report: Complete
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
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.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report: Not Applicable

Lineage:
Process_Step:
Process_Description:
During the Fugro Pelagos and CSUMB mapping missions, an Applanix Position and Motion Compensation System for Marine Vessels (POS/MV, 320, v4) was used to accurately position the vessels during data collection, and it also accounted for vessel's motion such as heave, pitch, and roll (position accuracy, +/-2 m; pitch, roll, and heading accuracy, +/-0.02; heave accuracy, +/-5%, or 5 cm). KGPS altitude data (Fugro Pelagos, StarFix HP & XP units; CSUMB, NavCom 2050) were used to account for tide cycle fluctuations and sound velocity profiles were collected with an Applied Microsystems SVPlus sound velocimeter. Soundings were corrected for vessel motion using the Applanix POS/MV data, for variations in water-column sound velocity using the AM SVPlus data, and for variations in water height (tides) using vertical-position data from the KGPS receivers. The multibeam backscatter data then were processed using Geocoder (Fugro Pelagos Modified Test Release 16) or Geocoder within Caris HIPS and SIPS. Within Geocoder, the backscatter intensities were radiometrically corrected (including despeckling and angle-varying gain adjustments), and the position of each acoustic sample was geometrically corrected for slant range. This processed imagery was stored as Georeferenced, Backscatter Rasters (GeoBARs). After GeoBARs were created for each line, they were mosaicked into 1-m or 2-m resolution images. Overlap between parallel lines was resolved using a priority table based on the distance of each sample from the ship track, with samples closest to- and furthest from- the ship track given the lowest priority. An anti-aliasing algorithm was also applied. The SWATHPlus backscatter data were processed using SXPTools v 2.0 (David Finlayson, USGS) and SEA Grid Processor v 3.02.19.0. SXPTools is a collection of command line programs that are used to enhance the quality of SEA SWATHplus interferometric sidescan sonar data. The programs are primarily focused on enhancing the backscatter quality, but there is some benefit to the bathymetry as well. The SXPTools sxpegn command was used to equalize the backscatter amplitude, and the sxpmagic command was used to help fill gaps and remove artifacts near nadir. After processing with SXPTools, lines were imported into Grid Processor and mosaicked into 1-m or 2-m resolution image georeferenced to UTM Zone 10 N, NAD_83(CORS96). The mosaic image for each survey block was exported as a GeoJpeg from Grid Processor and converted to GeoTiff using Adobe Photoshop or GIMP. In some cases memory limitations in Grid Processor required tiling a block mosaic into 2 or more sub-mosaics.


Process_Date: 2010
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Carrie Bretz
Contact_Organization: Seafloor Mapping Lab, California State University Monterey Bay
Contact_Position: Projects Manager, GIS; Metadata Supervisor
Contact_Address:
Address_Type: mailing and physical address
Address: 100 Campus Center, Bldg 13
City: Seaside
State_or_Province: CA
Postal_Code: 93955
Country: USA
Contact_Voice_Telephone: (831) 582-4197
Contact_Electronic_Mail_Address: carrie_bretz@csumb.edu


Process_Step:
Process_Description:
California Seafloor Mapping Project 1- or 2-m resolution backscatter imagery within this map were downloaded from California State University, Monterey Bay, Seafloor Mapping Lab (<http://seafloor.csumb.edu/SFMLwebDATA.htm>) and converted to grids. Backscatter grids of similar mapping systems were merged in a GIS and clipped to the boundary of the map area. Grids from different mapping systems were not merged together due to different mapping frequencies and processing techniques. Grids were projected horizontally to WGS-84 using ESRI ArcTools.
Process_Date: 2013
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Pete Dartnell
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Position: Physical Scientist
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Dr.
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: USA
Contact_Voice_Telephone: (831) 460-7415
Contact_Electronic_Mail_Address: pdartnell@usgs.gov


Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 8910
Column_Count: 8930
Vertical_Count: 1


Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:
UTM_Zone_Number: 10
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.9996
Longitude_of_Central_Meridian: -123.00000
Latitude_of_Projection_Origin: 0.00000
False_Easting: 500000.0
False_Northing: 0.00
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 2.0
Ordinate_Resolution: 2.0
Planar_Distance_Units: Meters
Geodetic_Model:
Horizontal_Datum_Name: WGS84
Ellipsoid_Name: WGS84
Semi-major_Axis: 6378137.00 meters
Denominator_of_Flattening_Ratio: 298.257223563


Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
The merged Reson 8101 acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes: 
Cell size = 2.0
Number of rows = 8900
Number of columns = 8885

Data type = unsigned integer

Boundary
Xmin = 473300
Xmax = 491070
Ymin = 4249780
Ymax = 4267580

Statistics
Minimum value = 0
Maximum value = 254
Mean = 124.90
Standard deviation = 24.62

Coordinate system description
Projection  UTM
Zone  10
Datum  WGS84
Units  meter
The merged Reson 7125 acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes: 
Cell size = 2.0
Number of rows = 8900
Number of columns = 8885

Data type = unsigned integer

Boundary
Xmin = 473300
Xmax = 491070
Ymin = 4249780
Ymax = 4267580

Statistics
Minimum value = 0
Maximum value = 254
Mean = 96.41
Standard deviation = 27.76

Coordinate system description
Projection  UTM
Zone  10
Datum  WGS84
Units  meter
The merged SWATHPlus acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes: 
Cell size = 2.0
Number of rows = 8900
Number of columns = 8885

Data type = unsigned integer

Boundary
Xmin = 473300
Xmax = 491070
Ymin = 4249780
Ymax = 4267580

Statistics
Minimum value = 1
Maximum value = 254
Mean = 112.70
Standard deviation = 41.48

Coordinate system description
Projection  UTM
Zone  10
Datum  WGS84
Units  meter
Entity_and_Attribute_Detail_Citation: none

Detailed_Description:
Entity_Type:
Entity_Type_Label: Value
Entity_Type_Definition: BackscatterA [8101] intensity value
Entity_Type_Definition_Source: ESRI
Attribute:
Attribute_Label: Rowid
Attribute_Definition: Internal feature number.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: VALUE
Attribute_Definition: Backscatter intensity values
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: 254
Attribute_Units_of_Measure: Integers representing intensity values
Attribute:
Attribute_Label: COUNT
Attribute_Definition:
The number of pixels (2m x 2m size grid cell) represented in each intensity value (see Attribute: VALUE).
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 11
Range_Domain_Maximum: 762541
Attribute_Units_of_Measure: Integers

Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: 345 Middlefield Rd
City: Menlo Park
State_or_Province: CA
Postal_Code: 94025-3561
Country: USA
Contact_Voice_Telephone: (650) 329-4309


Distribution_Liability:

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.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: TIFF
Format_Version_Number: ArcMap (version 10.0, ESRI , 2011)
Format_Specification:
Raster data layer is registered TIFF image in the UTM Zone 10 coordinate system with datum WGS84.
Format_Information_Content:
The .zip file for the TIFF image includes the image (.tif), the world registration file (.tfw), and the text (.txt) and XML (.tif.xml) versions of the metadata for the BackscatterA [8101] data layer of Offshore Salt Point, California.
File_Decompression_Technique: WinZip
Transfer_Size: 15.5
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
<https://pubs.usgs.gov/ds/781/OffshoreSaltPoint/data/BackscatterA_8101_OffshoreSaltPoint.zip>
Network_Resource_Name: <https://pubs.usgs.gov/ds/781/>
Access_Instructions: Data can be downloaded via the World Wide Web (WWW)
Fees: none
Technical_Prerequisites:
The downloadable data file has been compressed with the "zip" command and can be unzipped with Winzip (or other tool) on Windows systems. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing an Esri ArcMap TIFF. Users should download the ArcGIS Project File, OffshoreSaltPointGIS.mxd.zip, a compressed (with the "zip" command) version of the ArcMap document (.mxd) that has all the data layers loaded in the table of contents for "Offshore Salt Point" and has all the data symbolized as on the data release map sheets. Download and save this ArcGIS project file, including all data layers, to the directory the user has created for this GIS.

Metadata_Reference_Information:
Metadata_Date: 20140630
Metadata_Review_Date: 20150513
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Peter Dartnell
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Position: Physical Scientist
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Dr.
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: USA
Contact_Voice_Telephone: (831) 460-7415
Contact_Facsimile_Telephone: (831) 427-4709
Contact_Electronic_Mail_Address: pdartnell@usgs.gov
Metadata_Standard_Name:
Content Standard for Digital Geospatial Metadata ("CSDGM version 2")
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: universal time

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