Backscatter – Outer Mainland Shelf and Slope, Gulf of Santa Catalina, southern California, U.S. Geological Survey, 2010-2011

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Frequently anticipated questions:


What does this data set describe?

Title:
Backscatter – Outer Mainland Shelf and Slope, Gulf of Santa Catalina, southern California, U.S. Geological Survey, 2010-2011
Abstract:
In 2010 and 2011, the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), collected bathymetry and acoustic-backscatter data from the outer shelf and slope offshore the Oceanside region in southern California. These data were acquired as part of the USGS Marine Geohazards Program. Assessment of the hazards posed by offshore faults, submarine landslides, and tsunamis are facilitated by accurate and detailed bathymetric data. The surveys were conducted using the USGS R/V Parke Snavely outfitted with a 100 kHz Reson 7111 multibeam echosounder. While the surveys were focused on the collection of bathymetric data, the limited acoustic backscatter data are made available. These metadata describe the backscatter data provided in the report. The backscatter from the three separate surveys were not merged and these metadata describe the three separate backscatter images.
Supplemental_Information:
Information for the related USGS Pacific Coastal and Marine Science Center data collection field activities, S-11-10-SC, S-07-11-SC, and S-23-11-SC, online at <http://walrus.wr.usgs.gov/infobank/s/s1110sc/html/s-11-10-sc.meta.html>, <http://walrus.wr.usgs.gov/infobank/s/s0711sc/html/s-07-11-sc.meta.html>, and <http://walrus.wr.usgs.gov/infobank/s/s2311sc/html/s-23-11-sc.meta.html>.

  1. How should this data set be cited?

    United States Geological Survey (USGS), 20140509, Backscatter – Outer Mainland Shelf and Slope, Gulf of Santa Catalina, southern California, U.S. Geological Survey, 2010-2011:.

    Online Links:

    This is part of the following larger work.

    Dartnell, Peter, Conrad, James E., Ryan, Holy F., and Finlayson, David P., 20140509, Bathymetry and Acoustic Backscatter-Outer Mainland Shelf and Slope, Gulf of Santa Catalina, Southern California: Open-File Report OFR 2014-1094, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -117.86
    East_Bounding_Coordinate: -117.33
    North_Bounding_Coordinate: 33.46
    South_Bounding_Coordinate: 33.00

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2010
    Ending_Date: 2011
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Raster

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions, type Grid Cell

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 11
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117.00000
      Latitude_of_Projection_Origin: 0.00000
      False_Easting: 500000.0
      False_Northing: 0.00

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 10.0
      Ordinates (y-coordinates) are specified to the nearest 10.0
      Planar coordinates are specified in Meters

      The horizontal datum used is NAD83.
      The ellipsoid used is GRS80.
      The semi-major axis of the ellipsoid used is 6378137.00 meters.
      The flattening of the ellipsoid used is 1/0.003352811.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The 2010 backscatter imagery (USGS FACS-ID S-11-10-SC) was originally archived as a geoTIFF image with the following attributes:
    Cell size = 10.0
    Number of rows = 2788
    Number of columns = 1859
    
    Data type = floating point
    
    Boundary
    Xmin = 449545
    Xmax = 468125
    Ymin = 3652878
    Ymax = 3680743
    
    Statistics
    Minimum value = 0
    Maximum value = 255
    Mean = 211.43
    Standard deviation = 59.56
    
    Coordinate system description
    Projection  UTM
    Zone  11
    Datum  NAD83
    Units  meter
    
    The 2010 backscatter imagery (USGS FACS-ID S-23-10-SC) was originally archived as a geoTIFF image with the following attributes:
    Cell size = 10.0
    Number of rows = 4324
    Number of columns = 2636
    
    Data type = floating point
    
    Boundary
    Xmin = 430114
    Xmax = 456464
    Ymin = 3653270
    Ymax = 3696493
    
    Statistics
    Minimum value = 0
    Maximum value = 255
    Mean = 223.13
    Standard deviation = 55.64
    
    Coordinate system description
    Projection  UTM
    Zone  11
    Datum  NAD83
    Units  meter
    
    The 2011 backscatter imagery (USGS FACS-ID S-07-11-SC) was originally archived as a geoTIFF image with the following attributes:
    Cell size = 10.0
    Number of rows = 2168
    Number of columns = 3010
    
    Data type = floating point
    
    Boundary
    Xmin = 421818
    Xmax = 451904
    Ymin = 3678705
    Ymax = 3700375
    
    Statistics
    Minimum value = 0
    Maximum value = 255
    Mean = 229.42
    Standard deviation = 51.82
    
    Coordinate system description
    Projection  UTM
    Zone  11
    Datum  NAD83
    Units  meter
    
    Entity_and_Attribute_Detail_Citation: none


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Peter Dartnell
    U.S. Geological Survey, Pacifc Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridge Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    (831) 427-4709 (FAX)
    pdartnell@usgs.gov


Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) or other software to identify seafloor features. These data are not intended for navigational purposes.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 2011 (process 1 of 2)
    Three USGS surveys were conducted over a 2-year period (PCMSC Field Activity IDOs: S-11-10-SC, S-23-10-SC, and S-07-11-SC). The three surveys were conducted using a 100 kHz Reson 7111 multibeam echosounder. The 7111 is a horseshoe-shaped sonar that was mounted on the 34-foot USGS mapping vessel R/V Parke Snavely and affixed to a hull brace. Differentially Corrected Global Positioning System (DGPS) navigational data and measurements of vessel motion were combined in a CodaOctopus F190 inertial measurement unit (IMU) and passed to the sonar hardware and data collection software. Sound velocity measurements were collected continuously with an Applied Micro Systems Micro sound velocimeter (SV) deployed on the transducer frame for real-time sound velocity adjustments at the transducer-water interface. In addition, sound velocity profiles (SVP) were collected approximately every 2 hours throughout each survey day with an Applied Micro Systems. The navigation and vessel motion measurements were transmitted to the acquisition software in real time and combined with the instantaneous sound velocity measurements at the transducer head before each ping. The returned samples were projected to the seafloor using a ray-tracing algorithm working with the previously measured sound-velocity profiles in the acquisition software. Tide measurements relative to the North American Vertical Datum of 1988 (NAVD 1988) were downloaded from the La Jolla tide station 9410230. Original soundings were referenced to the World Geodetic System of 1984 (WGS 1984) relative to the North American Vertical Datum of 1988 (NAVD 1988).

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

    Date: 2013 (process 2 of 2)
    Backscatter data were processed using the Fledermaus (version 7.3.2) integration of Geocoder. Caris HDCS line files were exported as GSF line files and imported into Fledermaus along with the corresponding original S7K files. Adjustments were made to the line files including TX/RX (transmit/receive) power gain, beam pattern, and adaptive angle-varying gain corrections. The lines files were then mosaicked into 10-m resolution images. The images were then exported as georeferenced TIFF images, imported into a GIS, and converted to GRIDs at 10-m resolution. Grids were projected horizontally to the North American Datum of 1983 (NAD83, CORS96) using the ESRI "WGS_1984_(ITRF00)_To_NAD_1983_CORS96" function in ArcTools. Finally the GRIDs were exported as geoTIFF images.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Not applicable for raster data.

  2. How accurate are the geographic locations?

    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.

  3. How accurate are the heights or depths?

    Not applicable to backscatter data.

  4. Where are the gaps in the data? What is missing?

    Complete

  5. How consistent are the relationships among the observations, including topology?

    Unspecified


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:

USGS-authored or produced data and information are in the public domain. 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 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.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey
    345 Middlefield Rd
    Menlo Park, CA 94025-3561
    USA

    (650) 329-4309 (voice)

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?


    This database, identified as Backscatter of the outer mainland shelf and slope, Gulf of Santa Catalina, CA has been approved for release and publication by the U.S. Geological Survey (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 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.


  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 15-Sep-2013
Last Reviewed: 08-May-2014
Metadata author:
Peter Dartnell
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Physical Scientist
400 Natural Bridges Dr.
Santa Cruz, CA 95060-5792
USA

(831) 460-7415 (voice)
(831) 427-4709 (FAX)
pdartnell@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)


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