Topographic data from Whale's Tail marshes, South San Francisco Bay, California, 2021-2022

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Frequently anticipated questions:

What does this data set describe?

Title:
Topographic data from Whale's Tail marshes, South San Francisco Bay, California, 2021-2022
Abstract:
Topographic data were collected in the Whale's Tail marsh in southern San Francisco Bay between December 2021 and January 2022. The topographic data were acquired using global satellite navigation system receivers mounted on backpacks and hiked over the marsh surface.
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=2021-660-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., 20230412, Topographic data from Whale's Tail marshes, South San Francisco Bay, California, 2021-2022: data release DOI:10.5066/P972R6AW, 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., Lacy, Jessica R., McGill, Samantha C., WinklerPrins, Lukas T., Nowacki, Daniel J., Stevens, Andrew W., and Tan, Angela C., 2023, Hydrodynamic and sediment transport data from Whale's Tail marsh and adjacent waters in South San Francisco Bay, California 2021-2022: data release DOI:10.5066/P972R6AW, 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: -122.1455127
    East_Bounding_Coordinate: -122.1372418
    North_Bounding_Coordinate: 37.5914502
    South_Bounding_Coordinate: 37.5825473
  3. What does it look like?
    wt_topo_coverage_photos.png (PNG)
    Map of topographic data coverage and photos showing field equipment
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Dec-2021
    Ending_Date: 25-Jan-2022
    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 (26186)
    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 0.0000001. Longitudes are given to the nearest 0.0000001. 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: 0.001
      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:12/1/2021 7:20:57 PM
    Maximum:1/25/2022 9:51:20 PM
    Units:date and time in mm/dd/yyyy HH:MM:SS PM format
    longitude
    Longitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer Defined)
    Range of values
    Minimum:-122.1455127
    Maximum:-122.1372418
    Units:Decimal degrees
    latitude
    Latitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer Defined)
    Range of values
    Minimum:37.5825473
    Maximum:37.5914502
    Units:Decimal degrees
    easting
    East coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator(UTM) Zone 10 North, meters, coordinate system (Source: Producer Defined)
    Range of values
    Minimum:575444.229
    Maximum:576169.908
    Units:meters
    northing
    North coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system (Source: Producer Defined)
    Range of values
    Minimum:4159843.652
    Maximum:4160835.899
    Units:meters
    ellipsoid_ht
    Height in meters of data point with reference to the reference ellipsoid (Source: Producer Defined)
    Range of values
    Minimum:-32.308
    Maximum:-28.523
    Units:meters
    ortho_ht
    Height in meters of data point with reference to the North American Vertical Datum of 1988 computed using National Geodetic Survey Geoid18 offsets. (Source: Producer Defined)
    Range of values
    Minimum:0.257
    Maximum:4.038
    Units:meters
    h_precision
    Precision of the horizontal coordinate (95 percent confidence interval) estimated by the data acquisition software. (Source: Producer Defined)
    Range of values
    Minimum:0.009
    Maximum:0.046
    Units:meters
    v_precision
    Precision of the vertical coordinate (95 percent confidence interval) estimated by the data acquisition software. (Source: Producer Defined)
    Range of values
    Minimum:0.012
    Maximum:0.089
    Units:meters
    Entity_and_Attribute_Overview: The first line of the csv file is a header line
    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
  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?

Topographic data were collected as part of a study to quantify sediment fluxes and changes in marsh morphology at Whale's Tail marsh in southern San Francisco Bay.

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: 25-Jan-2022 (process 1 of 2)
    Topographic data were collected with GNSS receivers mounted on backpacks and hiked over the marsh surface. Prior to data collection, vertical distances between the GNSS antennas and the ground were measured using a tape measure. Hand-held data collectors running Trimble Access were used to log raw data and display navigational information allowing surveyors to navigate along planned survey lines. Orthometric heights in the North American Vertical Datum 1988 vertical datum were computed using National Geodetic Survey Geoid18 offsets.
    Date: 30-Aug-2022 (process 2 of 2)
    Raw topographic data were imported into Trimble Business Center for inspection. All available data were exported in comma-delimited text format for distribution. Person who carried out this activity:
    Andrew W. Stevens
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Oceanographer
    2885 Mission St.
    Santa Cruz, CA

    831-460-7424 (voice)
    astevens@usgs.gov
  3. What similar or related data should the user be aware of?
    Rydlund, Paul H., and Densmore, Brenda 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:

    Other_Citation_Details:
    Rydlund, P.H., Jr., and Densmore, B.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: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p. with appendixes.

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 positioning for the topographic surveys were achieved with global navigation satellite system (GNSS) receivers operating in real time kinematic mode with differential corrections from a single GNSS base station placed on a benchmark with established coordinates relative to the North American Datum of 1983 (2011 realization). The position of the GNSS base station was established using two static occupations conforming to level 1 quality as defined by Rydlund and others (2012). Uncertainty in the horizontal positions of the topographic data relative to the GNSS base station were estimated during acquisition using Trimble Access software and provided for each measurement in the dataset. The estimated uncertainty in horizontal positions at the 95 percent confidence interval ranged between 0.009 and 0.046 m with a mean of 0.018 m. Uncertainty in the horizontal positions associated with variable posture of the surveyor during data collection is unknown.
  3. How accurate are the heights or depths?
    Uncertainty in the elevations above the reference ellipsoid of relative to the GNSS base station were estimated during acquisition using Trimble Access software and provided for each measurement in the dataset. The estimated uncertainty in vertical positions at the 95 percent confidence interval ranged between 0.012 and 0.089 m with a mean of 0.030 m. Uncertainty in the horizontal positions associated with variable posture of the surveyor during data collection 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 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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission St.
    Santa Cruz, CA

    1-888-275-8747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? Topographic data are available as a comma-delimited text file (wt_topo.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-separated text file in format csv (version Trimble Business Center Version 5.60) Size: 2.4
      Network links: https://doi.org/10.5066/P972R6AW
    • Cost to order the data: None.

Who wrote the metadata?

Dates:
Last modified: 19-Apr-2023
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_P972R6AW/WT_topo_metadata.faq.html>
Generated by mp version 2.9.51 on Fri Apr 28 10:32:11 2023