Bathymetry of Whales Tail Marsh tidal creeks, South San Francisco Bay, California, 2023

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Frequently anticipated questions:

What does this data set describe?

Title:
Bathymetry of Whales Tail Marsh tidal creeks, South San Francisco Bay, California, 2023
Abstract:
Bathymetric data collected in Whales Tail Marsh tidal creeks, South San Francisco Bay, California, in 2023 with a shallow draft vessel equipped with a single-beam sonar system and global navigation satellite system (GNSS) receiver. The bathymetric data are provided in a comma-separated text file.
Supplemental_Information:
Additional information about the field activities from which these data were derived are available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-681-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Stevens, Andrew W., and Nowacki, Daniel J., 20240807, Bathymetry of Whales Tail Marsh tidal creeks, South San Francisco Bay, California, 2023: data release DOI:10.5066/P17ZUBYC, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Ferreira, Joanne C.T., Nowacki, Daniel J., and Stevens, Andrew W., 2024, Oceanographic, water-quality, bathymetric, and discharge data from Whales Tail Marsh tidal creeks, South San Francisco Bay, California, 2021-2023: data release DOI:10.5066/P17ZUBYC, U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: Ferreira, J.C.T., Nowacki, D.J., Stevens, A.W., 2024, Oceanographic, water-quality, bathymetric, and discharge data from Whales Tail Marsh tidal creeks, South San Francisco Bay, California, 2021-2023: U.S. Geological Survey data release, https://doi.org/10.5066/P17ZUBYC.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.144428
    East_Bounding_Coordinate: -122.137516
    North_Bounding_Coordinate: 37.592110
    South_Bounding_Coordinate: 37.582248
  3. What does it look like?
    cg23_overview_image.png (PNG)
    Map showing locations of bathymetric survey tracklines color-coded by elevation and equipment used during the bathymetric survey
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 14-Dec-2023
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (179425)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the dataset (Source: Producer defined)
    datetime_utc
    The date and time of data collection in Coordinated Universal Time (UTC). (Source: Producer Defined)
    Range of values
    Minimum:2023-12-14 18:52:53.642
    Maximum:2023-12-14 22:09:42.850
    Units:date and time in yyyy-mmm-dd HH:MM:SS.FFF format
    longitude
    Longitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer defined)
    Range of values
    Minimum:-122.144428
    Maximum:-122.137516
    Units:Decimal degrees
    latitude
    Latitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer defined)
    Range of values
    Minimum:37.582248
    Maximum:37.592110
    Units:Decimal degrees
    easting_m
    East coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM), zone 10, meters coordinate system (Source: Producer defined)
    Range of values
    Minimum:575541.34
    Maximum:576145.33
    Units:meters
    northing_m
    North coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM), zone 10, meters coordinate system (Source: Producer defined)
    Range of values
    Minimum:4159810.31
    Maximum:4160908.00
    Units:meters
    ellipsoid_ht_m
    Height in meters of data point relative to the GRS80 ellipsoid (Source: Producer defined)
    Range of values
    Minimum:-33.48
    Maximum:-30.48
    Units:meters
    ortho_ht_m
    Height in meters of data point with reference to the North American Vertical Datum of 1988. (Source: Producer defined)
    Range of values
    Minimum:-0.92
    Maximum:2.08
    Units:meters
    Entity_and_Attribute_Overview:
    Bathymetric data in .csv format. The first line of the csv file is a header line and the labels are defined in the entities and attributes section.
    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)
    • Andrew W. Stevens
    • Daniel J. Nowacki
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

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

Why was the data set created?

Data were obtained to characterize the depths of shallow tidal creeks in the Whales Tale Marsh complex. 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 topographic and shallow-water bathymetric features.

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: 14-Dec-2023 (process 1 of 3)
    Bathymetry data were collected on December 14, 2023, using a single-beam sonar system and global navigation satellite system (GNSS) receiver mounted on shallow draft survey vessel. The sonar system consisted of either a CEE Hydrosystems Ceescope single-beam echosounder and 200 kHz transducer with a 9-degree beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 3 mm. Depths from the echosounders were computed using sound velocity profiles measured using a YSI CastAway CTD during the survey. Positioning of the survey vessel was determined at 10 Hz using a survey-grade GNSS receiver. Output from the GNSS receiver and sonar system was combined in real time on a tablet computer running HYPACK 2020 hydrographic survey software.
    Date: 01-Feb-2024 (process 2 of 3)
    Survey-grade positions of the survey vessel were achieved with a single-base station and differential post-processing. Positioning data from the GNSS receiver were post-processed using Waypoint Grafnav to apply differential corrections from a GNSS base station with known horizontal and vertical coordinates relative to the North American Datum of 1983. Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid18 offsets. Bathymetric data were merged with post-processed positioning data, spurious soundings were removed, and the soundings were adjusted in areas with submerged vegetation, using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB 9.13.0.2080170. The final point data are projected in cartesian coordinates using the Universal Transverse Mercator (UTM), zone 10, meters coordinate system.
    Date: 16-May-2024 (process 3 of 3)
    All available bathymetry data from the survey were compiled into a comma-delimited text file for distribution.
  3. What similar or related data should the user be aware of?
    International Hydrographic Organization (IHO), 2008, IHO standards for hydrographic surveys (5th ed.): International Hydrographic Bureau Special Publication 44, 28p., Monaco.

    Rydlund, P.H., and Densmore, D.K., 2012, Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to establish vertical datum in the United States Geological Survey..

    Online Links:

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

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    Survey-grade positions of the survey vessel was achieved with global navigation satellite system (GNSS) receivers and a single GNSS base station placed on a benchmark. The position of the benchmark was determined using multiple static occupations resulting in a final position that conforms to level 1 quality (Rydlund and Densmore, 2012). Positioning data from the survey vessel were post-processed using Waypoint Grafnav software to apply differential corrections from the GNSS base station. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GNSS rover trajectories is 0.8 cm + 0.5 ppm. Baselines from the GNSS base station varied between 85 m and 1.3 km with a mean of about 600 m, suggesting the average horizontal accuracy of survey vessel positions to be about 1 cm. Uncertainty in the horizontal positions associated with pitch and roll of the survey vessel is unknown.
  3. How accurate are the heights or depths?
    Uncertainty in the final elevations is derived from the combination of uncertainty in the GNSS positioning and bathymetric sounding measurements. Uncertainty in the elevation of the geodetic benchmark used in the survey is less than 2 cm based on analysis of repeated static occupations. Manufacturer reported accuracy for the differentially corrected vertical positions for the GNSS rover trajectories is 1.5 cm + 1 ppm relative to the benchmark elevation. Baselines from the GNSS base station varied between 85 m and 1.3 km with a mean of about 600 m, suggesting the average vertical accuracy of survey vessel positions to be about 1.6 cm. The manufacturer of the single-beam echosounder used in this study reports a vertical accuracy of 1 cm. Additional uncertainty in the final computed elevations data is related to unmeasured variability in the speed of sound used to compute depths from bathymetric soundings and, thus, is depth-dependent. Based on analysis of available speed of sound measurements, we estimate uncertainties in the final depth soundings to be no greater than 1 percent of the water depth. The total vertical uncertainty is calculated using the constant- and depth-dependent factors summed in quadrature (International Hydrographic Organization, 2008). The mean uncertainty in processed elevations is estimated to be about 4 cm. Additional uncertainty in the vertical positions associated with pitch and roll of the survey vessels or the presence of submerged vegetation is unknown.
  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?
    All data falls within expected ranges.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints no access constraints
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 navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA
    USA

    1-831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? Bathymetry data are available as a comma-delimited text file (cg23_bathy.csv), along with associated 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?
    • Availability in digital form:
      Data format: comma-delimited text file in format comma-delimited text (version Matlab 9.13.0.2080170) text Size: 13.7
      Network links: https://doi.org/10.5066/P17ZUBYC
    • Cost to order the data: None

Who wrote the metadata?

Dates:
Last modified: 07-Aug-2024
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission St.
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_P17ZUBYC/cg23_bathy_metadata.faq.html>
Generated by mp version 2.9.51 on Thu Aug 15 16:08:33 2024