Distribution of particle size in suspension at various depths from San Pablo Bay and Grizzly Bay, California, 2019

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Frequently anticipated questions:

What does this data set describe?

Distribution of particle size in suspension at various depths from San Pablo Bay and Grizzly Bay, California, 2019
These data present suspended particle size distributions collected by the U.S. Geological Survey (USGS) Pacific Coastal and Marine Science Center within two embayments of San Francisco Bay. Data were collected at one site in San Pablo Bay and one site in Grizzly Bay from June through August 2019, by deploying a Sequoia Scientific Laser In-situ Scattering and Transmissometry instrument (LISST 100x) from a small vessel near pre-established USGS instrument moorings. At both sites, data were collected on six dates at three depths, generally near the water surface, at mid depth, and near the sediment bed, for 1-3 minutes at each depth. LISST volume concentrations are most accurate when the optical percent transmission is above 30, as light passing through the sample volume is unlikely to be scattered by more than one particle. One file (ERO19PBP04) was removed due to poor data quality throughout the file. These files contain all samples collected; judgment should be applied when using them. Users are advised to check metadata and instrument information carefully for applicable time periods of specific data.
Additional information about the field activities from which these data were derived is available online at:
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?
    Allen, Rachel M., 20201231, Distribution of particle size in suspension at various depths from San Pablo Bay and Grizzly Bay, California, 2019: data release doi:10.5066/P9P7I65U, U.S. Geological Survey, Pacific Coastal and Marine Science Center Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Lacy, Jessica R., McGill, Samantha C., Joanne C. T. Ferreira, Allen, Rachel M., WinklerPrins, Lukas, and Tan, Angela C., 2020, Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay , California, 2019: data release doi:10.5066/P9P7I65U, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.6160
    East_Bounding_Coordinate: -121.9456
    North_Bounding_Coordinate: 38.17843
    South_Bounding_Coordinate: 37.95883
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5f40599882ce8df5b6cb4a03 ?name=ERO19_study_area .jpg&allowOpen=true (JPEG)
    Digital elevation model (DEM) of study area showing locations of USGS moorings in San Pablo Bay (PBM) and Grizzly Bay (GBM).
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Jun-2019
    Ending_Date: 20-Aug-2019
    Ground condition at time data were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: NetCDF files
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Data were collected at each site and each depth for 1-3 minutes. Refer to self-contained NetCDF files for more location information.
    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 1.0E-5. Longitudes are given to the nearest 1.0E-5. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is World Geodetic System 1984 (WGS84).
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    NetCDF files are self-contained and attribute information may be found in the header of the file itself.
    The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Rachel M. Allen
  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)

Why was the data set created?

These data were collected for the purpose of estimating particle settling velocity. They were collected as part of a collaborative study between the USGS Coastal and Marine Hazards and Resources Program, the USGS California Water Science Center, and the USGS Water Resource Mission Area investigating physical and biological controls on bed erodibility. These data are intended for researchers, students, 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-Aug-2019 (process 1 of 3)
    Profiles were collected in Grizzly Bay and San Pablo Bay using the Sequoia Scientific LISST-100X, near the Grizzy Bay Mooring site (GBM) and the San Pablo Bay Mooring site (PBM).
    Date: 23-Oct-2020 (process 2 of 3)
    Data were accumulated into NetCDF files. Out-of-water data were removed from the files.
    Date: 23-Oct-2020 (process 3 of 3)
    Files were named with a convention that uses a 12-digit alpha-numeric code. The first three characters for this dataset are all 'ERO' for the experiment name; the fourth and fifth positions represent the calendar year in which the first data point in the file was taken (19, 2019); the sixth and seventh characters are an alphanumeric code for the embayment (for example, GB refers to Grizzly Bay) the eighth character is 'P', to represent the method of collection used (Profiling). The ninth and tenth characters represent the time index of the profile, starting at 01 for the first profile, and ending at 06 for the last one. The eleventh and twelfth characters are "ls" for the Sequoia Scientific LISST-100X. Data from San Pablo Bay and data from Grizzly Bay are provided in separate zip files.
  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?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    Horizontal accuracy derived from the boat’s GPS instrumentation is less than 5 m.
  3. How accurate are the heights or depths?
    Vertical positioning is reported within each data file as pressure from the water surface. Accuracy depends on the presence of waves, and calibration and sensitivity of the pressure sensor, and resulted in combined uncertainty of about 15 cm. Depth above bottom can be computed by referencing the collection time and the total water depth reported in the time series files.
  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. Data fall 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
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 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)
  2. What's the catalog number I need to order this data set? These data are available in zipped NetCDF format and are accompanied by 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 archive utilities. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing a NetCDF file. These data can be viewed with the NOAA netCDF file viewer, ncBrowse, which can be downloaded from the internet at https://www.pmel.noaa.gov/epic/java/ncBrowse.

Who wrote the metadata?

Last modified: 31-Dec-2020
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA
United States

831-427-4747 (voice)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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