Multibeam bathymetry data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA

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Frequently anticipated questions:

What does this data set describe?

Title:
Multibeam bathymetry data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA
Abstract:
These metadata describe bathymetry collected during a 2015 multibeam echosounder survey near Cross Sound, southeast Alaska. Data were collected by the U.S. Geological Survey (USGS) and the Alaska Department of Fish and Game (ADFG) aboard the ADFG R/V Solstice during USGS field activity 2015-629-FA. The bathymetry data are published here as a 32-bit GeoTIFF image.
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=2015-629-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?
    Dartnell, Peter, Brothers, Daniel S., and Haeussler, Peter J., 20220919, Multibeam bathymetry data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA: data release DOI:10.5066/F7JH3KG6, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Dartnell, Peter, Brothers, Daniel S., and Haeussler, Peter J., 2022, Multibeam bathymetry and acoustic-backscatter data collected in 2015 near Cross Sound, southeast Alaska, during field activity 2015-629-FA: data release DOI:10.5066/F7JH3KG6, 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: -137.202
    East_Bounding_Coordinate: -136.217
    North_Bounding_Coordinate: 58.426
    South_Bounding_Coordinate: 57.808
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5abbf417e4b081f61abd5bd2?name=CrossSound_2015_bathy_10m_UTM08_WGS84_QV.jpg&allowOpen=true (JPEG)
    Quick view image of 2015 Cross Sound shaded-relief bathymetry data
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 05-May-2015
    Ending_Date: 21-May-2015
    Currentness_Reference:
    ground condition at time data were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GeoTIFF
  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 6746 x 5632 x 1, 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: 8
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -135.00000
      Latitude_of_Projection_Origin: 0.00000
      False_Easting: 500000.0
      False_Northing: 0.00
      Planar coordinates are encoded using row and column
      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 WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.00.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: World Geodetic Datum 1984
      Altitude_Resolution: 0.1
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    value
    depth in meters relative to the WGS84 ellipsoid (Source: Producer defined)
    Entity_and_Attribute_Overview:
    The complete 10-m resolution 2015 Cross Sound bathymetry grid was originally archived as a TIFF image with the following attributes. 
    Cell size = 10.0
Number of rows = 6746
Number of columns = 5632

Data type = floating point

Boundary
Xmin = 371385
Xmax = 427705
Ymin = 6409385
Ymax = 6476845

Statistics
Minimum value = -427.54
Maximum value = -6.74
Mean = -190.72
Standard deviation = 91.60

Coordinate system description
Projection  UTM
Zone  8
Datum  WGS84
Vertical Reference WGS84
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)
    • Peter Dartnell
    • Daniel S. Brothers
    • Peter J. Haeussler
  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?

These metadata describe the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC) 2015 bathymetry data collected near Cross Sound, southeast Alaska that is provided as a 10-m resolution TIFF image. In 2015 the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC)in cooperation with the Alaska Department of Fish and Game (ADFG) collected bathymetry and acoustic backscatter data near Cross Sound in southeast Alaska using an Reson 7111 multibeam echosounder mounded to the ADFG R/V Solstice. The survey was conducted to map the offshore expression of the Queen Charlotte fault system that runs for approximately 500 kilometers off the coast of southeast Alaska and British Columbia. This was the first in a series of surveys to map the entire offshore component of the fault. The fault system has generated numerous powerful earthquakes in the magnitude 7 and 8 range. This new mapping will help understand the fault's slip rate, earthquake recurrence intervals, and paleoseismic history. 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 bathymetric features. These data are not intended to be used for navigation.

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: 2020 (process 1 of 1)
    In May 2015 the USGS, PCMSC mapped offshore Cross Sound in southeast Alaska over the northern section of the Queen Charlotte fault. A Reson 7111 multibeam echosounder was pole-mounted to the Alaska Department of Fish and Game R/V Solstice. The survey line files were imported into Caris HIPS and SIPS software (version 9) for bathymetric processing. Water column sound velocity data that was collected throughout the survey was applied to the bathymetry data and verified tides from the Elfin Cove tide station (9452634) were applied in post-processing. The data were cleaned of obvious bad soundings and the soundings were gridded into a 10-m surface. The surface was exported as an ASCIIRaster file and imported into a Geographic Information System (GIS). The bathymetry grid was transformed to UTM zone 8, WGS84 coordinates, vertically referenced to the WGS84 ellipsoid using datum offset values from NOAA's VDatum tool, https://vdatum.noaa.gov/welcome.html. A value of 0.12m was added to the MLLW grid to transform to NAVD88 and then a value of 3.1m was added to transform to WGS84. The bathymetry grid was then exported as a GeoTIFF file in UTM zone 8, WGS84 coordinates, vertically reference to the WGS84 ellipsoid (CrossSound_2015_bathy_10m_UTM08_WGS84_WGS84.tif).
  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?
    The Coda Octopus F180 position and motion compensation system has a horizontal positional accuracy of about 0.4 m with DGPS correstions and roll and pitch accuracies of about 0.025 degrees (https://www.oceanscan.net/gallery/Data_Sheets/CODA_F180_PRECISION_ALTITUDE__POSITIONING_SYSTEMS.pdf). Accuracies of final products may be lower due 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?
    The Coda Octopus F180 position and motion compensation system has heave accuracy between 3.5cm - 5cm (https://www.oceanscan.net/gallery/Data_Sheets/CODA_F180_PRECISION_ALTITUDE__POSITIONING_SYSTEMS.pdf). Accuracies of final products may be lower due 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.
  4. Where are the gaps in the data? What is missing?
    A couple of transit or test lines that are in the tracklines shapefile are not included in the bathymetry grid. 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 and the Alaska Department of Fish and Game as the originators 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 GeoTIFF format, including a tif world file (.tfw) and CSDGM FGDC-compliant metadata.
  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 a GeoTIFF file.

Who wrote the metadata?

Dates:
Last modified: 19-Sep-2022
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/DataReleases/ScienceBase/DR_F7JH3KG6/CrossSound_2015_bathy_10m_UTM08_WGS84_WGS84_metadata.faq.html>
Generated by mp version 2.9.51 on Fri Sep 23 09:58:22 2022