Donated AUV Chirp seismic-reflection data collected during Monterey Bay Aquarium Research Institute (MBARI) cruise in April 2018 offshore of south-central California

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Frequently anticipated questions:

What does this data set describe?

Title:
Donated AUV Chirp seismic-reflection data collected during Monterey Bay Aquarium Research Institute (MBARI) cruise in April 2018 offshore of south-central California
Abstract:
This dataset consists of autonomous underwater vehicle (AUV) Chirp seismic-reflection data collected in April 2018 aboard the R/V Rachel Carson, which is owned and operated by the Monterey Bay Aquarium Research Institute (MBARI). During the cruise, data were collected across eight AUV dives, six of which collected coincident bathymetry and Chirp seismic-reflection data (two dives collected Chirp seismic-reflection data only). The collection of these data was funded entirely by MBARI, and the data have been donated to the U.S. Geological Survey (USGS). The data were collected in collaboration with the USGS and the Bureau of Ocean Energy Management (BOEM) and they are located in the same study area as the collaborative California Deepwater Investigations and Groundtruthing I (Cal DIG I) project. The purpose of the overall Cal DIG I study is to assess shallow geohazards, benthic habitats, and thereby the potential for alternative energy infrastructure (namely floating wind turbines) offshore south-central California due to the study area's proximity to power grid infrastructure associated with the Morro Bay power plant. The AUV data in this portion of the data release provide ultra-high-resolution subsurface imaging of eight different patches of seafloor offshore of the south-central California coast. The AUV mapping navigation has not been accurately positioned and is considered as only partially processed.
Supplemental_Information:
Additional information about the USGS field activity from which these data were derived is available online at:
http://cmgds.marine.usgs.gov/2021-603-DD
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?
    Kennedy, Daniel J., Walton, Maureen A.L., Cochrane, Guy R., Paull, Charles K., Caress, David W., Anderson, Krystle, Lundsten, Eve, and Gilbane, Lisa, 20210823, Donated AUV Chirp seismic-reflection data collected during Monterey Bay Aquarium Research Institute (MBARI) cruise in April 2018 offshore of south-central California: data release DOI:10.5066/P97QM7NF, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California..

    Online Links:

    This is part of the following larger work.

    Kennedy, Daniel J., Walton, Maureen A.L., Cochrane, Guy R., Paull, Charles K., Caress, David W., Anderson, Krystle, Lundsten, Eve, and Gilbane, Lisa, 2021, Donated AUV bathymetry and Chirp seismic-reflection data collected during Monterey Bay Aquarium Research Institute cruises in 2018-2019 offshore of south-central California: data release DOI:10.5066/P97QM7NF, 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: -121.957
    East_Bounding_Coordinate: -121.22
    North_Bounding_Coordinate: 35.288
    South_Bounding_Coordinate: 35.862
  3. What does it look like?
    MBARI_AUVChirp_April2018_thumbnail.png (PNG)
    Bathymetry map offshore of south-central California overlaid with MBARI-donated AUV survey data in purple.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 25-Apr-2018
    Ending_Date: 28-Apr-2018
    Currentness_Reference:
    Ground conditions at time data were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Chirp seismic-reflection data in SEG-Y format
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Data were collected offshore of south-central California. SEG-Y file headers contain location information.
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 UTM Zone 10N.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -121.45
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in Meter
      The horizontal datum used is World Geodetic System 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: North American Vertical Datum 1988 (NAVD-88)
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    value
    depth in meters relative to NAVD-88 (Source: Producer defined)
    Entity_and_Attribute_Overview:
    The partially complete AUV Chirp was originally achieved as a collection of 0.5-2.0 m resolution seismic profiles recorded in SEG-Y format.
    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)
    • Daniel J. Kennedy
    • Maureen A.L. Walton
    • Guy R. Cochrane
    • Charles K. Paull
    • David W. Caress
    • Krystle Anderson
    • Eve Lundsten
    • Lisa Gilbane
  2. Who also contributed to the data set?
    The donated data were collected aboard the R/V Rachel Carson, which is owned and operated by the Monterey Bay Aquarium Research Insitute.
  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?

The goal of this part of the Cal DIG I study is to collect overlapping multibeam bathymetric and Chirp seismic-reflection data Chirp offshore of south-central region of California for the purpose of improving regional models of seafloor (benthic) habitats, sediment transport, and assessing potential geologic hazards.

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: 28-Apr-2018 (process 1 of 2)
    Detailed seafloor surveys were conducted using an AUV developed at the Monterey Bay Aquarium Research Institute (MBARI) specifically for seafloor mapping. The vehicle carried a Reson 7125 400kHz multibeam sonar and an Edgetech 2205 1-6 kHz Chirp subbottom profiler. The AUV was preprogrammed to proceed to more than 50 waypoints during the dives while traveling at 3 knots and maintaining an altitude of 50 m off the seafloor. Track lines were spaced 140-150 m apart. In this mode, the AUV obtains overlapping multibeam bathymetric coverage at a vertical resolution of 0.15 m and a horizontal footprint of 0.87 m, and Chirp seismic-reflection profiles with a vertical resolution of 0.11 m.
    Date: 13-Oct-2021 (process 2 of 2)
    Performed minor edits to the metadata to correct typos. No data were changed Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@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?
    The AUV system developed at MBARI has an estimated vertical depth uncertainty ranging from about 0.05 m to 2.0 m over a horizontal range of 0 to 5 m. 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 and datum transformations. The subbottom data were collected from a submerged platform for which both the vertical position and the altitude over the seafloor are variable. In any time section or depth section, the data start at the location of the sonar in time or depth. The trace is recorded in two-way travel time (seconds), but the sonar depth is recorded to the headers 49-52, 61-64, and 65-68 (in meters), with a scalar (divisor) of -100 in headers 69-72. The sonar depth must be converted to two-way travel time seconds using 1500 m/s which can then be added to the Chirp trace to correct for water depth and display the data in two-way travel time (seconds). Horizontal X and Y locations for the seismic profile locations are provided and stored in the SEG-Y data trace headers in header bytes 81 and 85 with a scalar of 1.
  2. How accurate are the geographic locations?
    Position data derive from an onboard inertial navigation system (INS) that has drift bounded by 0.05 percent of distance traveled when aided by Doppler Velocity Log (DVL) velocity over ground observations. The raw INS positions are adjusted in post processing so that bathymetric features match in overlapping swath data. Following the navigation adjustment relative position accuracy within the surveys is less than 2 m. The absolute position accuracy is dominated by Ultra Short Base Line (USBL) tracking of the AUV at the beginning of missions, which is less than 30 m. Bottom positions were modified using MBSystem NavAdjust to make bathymetric features in overlapping swaths and crossing swath match. Data have not been adjusted to match surface ship collected multibeam bathymetry.
  3. How accurate are the heights or depths?
    Depths shown in the seismic-reflection data files are in milliseconds (round trip travel time) and are referenced to sea level. Vertical accuracy ranges between +/- 0.2 and 1 meter.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered partially complete for the information presented. AUV mapping data have not had the navigation corrected. 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 Monterey Bay Aquarium Research Institute (MBARI) as the originator(s) of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey – CMGDS
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? Zip files contain partially processed AUV Chirp seismic-reflection data in zipped SEG-Y format. The data are divided up into folders by dive and presented by navigation line, as reflected in the individual file name(s). Download sizes range from 2.1 to 4.3 GB.
  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?
    • Availability in digital form:
      Data format: Zip files contain the partially processed AUV Chirp seismic-reflection data divided into folders by dive with individual files per navigation line. Download sizes range from 2.1 to 4.3 GB. in format SEG-Y (version SEG-Y rev 1) Size: 4300
      Network links: https://doi.org/10.5066/P97QM7NF
    • Cost to order the data: None.

  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. Use of SEG-Y data requires specialized software, such as ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX by Paradigm Geophysical; SPW by Parallel Geoscience; VISTA by Seismic Image Software; SeiSee by Dalmorneftegeophysica (DMNG); amongst others.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2021
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/CMGDS_DR_tool/DR_P97QM7NF/2021-603-DD_chirp_201804_metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:20 2021