High-resolution acoustic backscatter data collected southwest of Chenega Island, Alaska during field activity 2014-622-FA

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Frequently anticipated questions:


What does this data set describe?

Title:
High-resolution acoustic backscatter data collected southwest of Chenega Island, Alaska during field activity 2014-622-FA
Abstract:
High-resolution acoustic backscatter data were collected by the U.S. Geological Survey (USGS) and the Alaska Department of Fish and Game in May of 2014 southwest of Chenega Island, Alaska. Data were collected aboard the Alaska Department of Fish and Game vessel, R/V Solstice, during USGS field activity 2014-622-FA, using a pole mounted 100-kHz Reson 7111 multibeam echosounder.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2014-622-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Balster-Gee, Alicia F., Brothers, Daniel S., Finlayson, David P., Liberty, Lee, Dartnell, Peter, Hatcher, Gerry A., Haeussler, Peter J., and Byerly, Mike, 2019, High-resolution acoustic backscatter data collected southwest of Chenega Island, Alaska during field activity 2014-622-FA: data release DOI:10.5066/P9K1YQ35, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Balster-Gee, Alicia F., Brothers, Daniel S., Finlayson, David P., Liberty, Lee, Dartnell, Peter, Hatcher, Gerry A., Haeussler, Peter J., and Byerly, Mike, 2019, Bathymetry, acoustic backscatter, and minisparker seismic-reflection datasets collected southwest of Montague Island and southwest of Chenega, Alaska during field activity 2014-622-FA: data release DOI:10.5066/P9K1YQ35, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -148.297885
    East_Bounding_Coordinate: -147.954768
    North_Bounding_Coordinate: 60.336390
    South_Bounding_Coordinate: 60.198236
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5c5ccc99e4b0fe48cb31259b?name=2014-622-FA_Chenega_UTM6N_10m_Backscatter_map.png&allowOpen=true (PNG)
    Map showing acoustic-backscatter data southwest of Chenega Island
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-May-2014
    Ending_Date: 22-May-2014
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: TIFF
  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 1507 x 1873, 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: 6N
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 10.000000
      Ordinates (y-coordinates) are specified to the nearest 10.000000
      Planar coordinates are specified in Meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    Value
    depth relative to Mean Lower Low Water (Source: Producer defined)
    Entity_and_Attribute_Overview:
    10-m resolution merged Southwest Chenega Island, Gulf of Alaska bathymetry grid was originally archived as a TIFF image with the following attributes. >Cell size = 10.0, 10.0 >Number of rows = 1507 >Number of columns = 1873 >Data type = floating point >Boundary >Xmin = 428340.001761 >Xmax = 447070.001761 >Ymin = 6674190.001763 >Ymax = 66892060.001763 >Statistics >Minimum value = 0 >Maximum value = 172 >Mean = 100.3164779513307 >Standard deviation = 8.296661089153924 >Coordinate system description >Projection UTM >Zone 06 >Datum NAD83 >Vertical Reference MLLW >Units meter
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Alicia F. Balster-Gee
    • Daniel S. Brothers
    • David P. Finlayson
    • Lee Liberty
    • Peter Dartnell
    • Gerry A. Hatcher
    • Peter J. Haeussler
    • Mike Byerly
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

This work was funded by the U.S. Geological Survey (USGS) Coastal and Marine Hazards and Resources Program (CMHRP) Marine Geohazards Project and the Alaska Department of Fish and Game (ADFG). The high-resolution bathymetry of bedrock, sediment deposits, and tectonic structure provide geologic information that is essential to hazard assessment, regional sediment management, and coastal and marine spatial planning at Federal, State, and local levels, as well as to future research on the geomorphic, sedimentary, tectonic, and climatic record of southeastern Alaska. These data and information are intended for science researchers, students from elementary through college, policy makers, and the general public.

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: 15-Feb-2019 (process 1 of 2)
    In 2014, the U.S. Geological Survey (USGS), in cooperation with the Alaska Department of Fish and Game (ADFG) mapped offshore the southwest corner of Chenega Island and near Chenega Alaska. A 100-kHz Reson 7111 multibeam echosounder was pole-mounted to the ADFG R/V Solstice, and an Applanix POS-MV (Position and Orientation System for Marine Vessels) was used to position the vessel during data collection where it also accounted for vessel motion such as heave, pitch, and roll. The POS-MV also recorded position and vessel motion parameters for later post-processing. Soundings were corrected real-time using inputs from the POS-MV and corrected for water column sound velocity variations using sound velocity values calculated from CTD casts. In 2019, the Reson 7111 S7K line files were downloaded from USGS archives and imported into SonarWiz processing software (version 6). The S7K line files were processed for backscatter and gridded into 10-m resolution grids. The grids were exported as Erdas Imagine files in UTM, zone 6, WGS84 coordinates. The grids were imported in ESRI ArcMap and converted to geoTIFFs.
    Date: 20-Jun-2019 (process 2 of 2)
    Edits were made to standardize a few of the "None" keywords. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission St.
    Santa Cruz, CA
    United States

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Brothers, Daniel S., Haeussler, Peter J., Liberty, Lee, Finlayson, David, Geist, Eric, Labay, Keith, and Byerly, Mike, 2016, A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska.

    Online Links:

    Other_Citation_Details:
    Brothers and others, 2016, A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska: Earth and Planetary Science Letters, v. 438, p.112-121.

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

  1. How well have the observations been checked?
    The accuracy of the Reson acoustic-backscatter data is unknown since it is believed the backscatter is uncalibrated. Also, during post-processing, the backscatter data from all repeat mapping surveys were gain normalized together so the backscatter data in this report differ from the original individual surveys' data.
  2. How accurate are the geographic locations?
    The stated accuracy of the Applanix POS-MV post-processed horizontal position is about 0.1 m, with roll and pitch stated accuracies of about 0.02 degrees (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-WaveMaster-II.pdf). Accuracies of final products may be lower due to 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 acoustic-backscatter data
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted.

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 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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in TIFF format, including a tiff world file (.tfw), and accompanied by FGDC-compliant metadata and a browse graphic.
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    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 ASCIIRaster file.

Who wrote the metadata?

Dates:
Last modified: 20-Jun-2019
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/alaska/2014-622-FA_Chenega_UTM6N_10m_Backscatter_metadata.faq.html>
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