Wind-wave, and turbidity time-series data from Little Holland Tract (station HWA), Sacramento-San Joaquin Delta, California

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Frequently anticipated questions:

What does this data set describe?

Wind-wave, and turbidity time-series data from Little Holland Tract (station HWA), Sacramento-San Joaquin Delta, California
Time series data of water surface elevation, wave height, and turbidity were collected in Little Holland Tract (LHT) beginning in August 2015 as part of “Wind-wave and suspended-sediment data from Liberty Island and Little Holland Tract, Sacramento-San Joaquin Delta, California”. The turbidity sensors were calibrated to suspended-sediment concentration measured in water samples collected on site. The calibration and fit parameters for all of the turbidity sensors used in the study are tabulated and provided with the data. Data were sequentially added to this data release as they were collected and post-processed.
  1. How might this data set be cited?
    Lacy, Jessica R., and Carlson, Emily M., 2016, Wind-wave, and turbidity time-series data from Little Holland Tract (station HWA), Sacramento-San Joaquin Delta, California: data release DOI:10.5066/F73R0R07.

    This is part of the following larger work.

    Lacy, Jessica R., and Carlson, Emily M., 2016, Wind-wave, current and wave velocity, and turbidity time-series data from Liberty Island and Little Holland Tract, Sacramento-San Joaquin Delta, California: data release DOI:10.5066/F73R0R07, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.6917
    East_Bounding_Coordinate: -121.6533
    North_Bounding_Coordinate: 38.32737
    South_Bounding_Coordinate: 38.24528
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 04-Aug-2015
    Ending_Date: 11-Dec-2015
    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?
      This is a Point data set.
    2. What coordinate system is used to represent geographic features?
  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)
    • Jessica R. Lacy
    • Emily M. Carlson
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jessica R. Lacy
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Research Oceanographer
    2885 Mission Street
    Santa Cruz, CA

    831-460-7520 (voice)
    831-427-4748 (FAX)

Why was the data set created?

These data will be used to determine the range of turbidity and suspended-sediment concentration (SSC) in Little Holland Tract and the extent to which wind waves contribute to turbidity, to investigate physical attributes of flooded habitats that promote enhanced turbidity, and to evaluate the potential for flooded agricultural tracts to contribute to elevated turbidity in adjacent waters.

How was the data set created?

  1. From what previous works were the data drawn?
    IEM (source 1 of 1)
    The Iowa Environmental Mesonet (IEM), 2016, ASOS-AWOS-METAR Data Download: Iowa State University, Ames, IA.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source information used in support of the development of the dataset. Local atmospheric readings were obtained from the IEM database to use during post-processing of the data to adjust for local atmospheric deviations.
  2. How were the data generated, processed, and modified?
    Date: 04-Aug-2015 (process 1 of 6)
    Instruments incuded in deployment are: RBR duo bursting pressure sensor, and RBR virtuoso turbidity meter.
    Date: 08-Oct-2015 (process 2 of 6)
    Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
    Date: 07-Dec-2015 (process 3 of 6)
    Instruments were removed from station. End of data collection.
    Date: 11-Dec-2015 (process 4 of 6)
    Data were accumulated into NetCDF files. During post-processing, data collected when instruments were out of the water, and data degraded by biological fouling, were removed from the time series. Bad data points were identified by 1) the deployment and recovery times, 2) pressure readings equal to or less than 3 cm of water, 3) amplitude or correlation values outside of predetermined quality thresholds for the velocimeter. Pressure data were adjusted from absolute pressure to hydrostatic pressure by removing local atmospheric pressure. Local atmospheric pressure was obtained from IEM for the Travis Air Force Base (SUU) station, which is located 15 miles from the study site.
    Date: 11-Dec-2015 (process 5 of 6)
    Optical Backscatter (OBS) data were put through a rigorous cleaning process, as these types of data are inherently noisy. First, the data were inspected for extended periods of time (typically many days) of unrealistic values that did not follow typical trends. These periods of bad data, believed to be caused by vegetation blocking the sensor, were manually removed from the time series. Second, large values of the first derivative of the time series were removed, which indicate unrealistic single point spikes in the data. Spikes were identified by change thresholds of +/-70 mg/L for the burst-average time series and +/-1 mg/L within the bursts. Third, readings above 90 percent of the maximum instrument voltage were removed. In particularly noisy data, points deviating more than 3 standard deviations from the running mean were removed. Finally, 'island' points were identified (and removed) by checking for real-value points with both neighbors flagged as bad. Bad data points were then replaced by linear interpolation, except for the large chunks that were removed in the first step of filtering. The OBS data were converted to suspended-sediment concentration using calibration constants derived from linear regression between OBS data and sediment concentration measured in water samples collected in the study area.
    Date: 11-Dec-2015 (process 6 of 6)
    Files are named with a convention that uses a 13-digit alpha-numeric code. The first two characters for this dataset are all 'DL' for the experiment name. The third character is a number indicating which deployment period the data comes from (1, 2, 3, etc.); the fourth and fifth positions represent the calendar year in which the first data point in the file was taken (15, 2015; 16, 2016; 17, 2017). The sixth position is a letter indicating the water body/region (L, Liberty Island; H, Little Holland Tract). The seventh position is a letter representing the station type (V, velocity station; W, wind-wave station). The eighth position represents the location of the station (A, B, C, etc.) within the water body/region. Next is a three-character code for the instrument type (vec, Nortek's Acoustic Doppler Velocimeter; rbr, RBR's bursting pressure sensor; ctd, RBR's CTD; vir, RBR's Virtuosos turbidity sensor). There are an additional two characters for the instruments that collect in a bursting pattern to indicate if the burst is included in the file or the statistics of the burst, this indicator is omitted if there is no bursting pattern (-b, burst; -s, statistics).
  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?
    A formal accuracy assessment of the horizontal positional information in the data set has either not been conducted, or is not applicable.
  3. How accurate are the heights or depths?
    There are two sources of uncertainty associated with vertical positioning of the instruments: 1) the measuring tools used during instrument mounting, 2) the amount of settling that occurs during deployment. There was no evidence that the platforms settled to a large degree, they are easily lifted by one person, the sediment tends to be very compacted in the study area, and analysis of distance to bed data did not show gradients over the duration of deployment. The measuring tools used to mount the instruments onto the platforms have a resolution of 0.1 cm resulting in an uncertainty of 0.05 cm.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Data will be sequentially added to this data release as they are retrieved and post-processed. Users are advised to read the metadata for each part of this data release carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    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 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 - 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? Downloadable time-series data in NetCDF format.
  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?

Who wrote the metadata?

Last modified: 16-Dec-2016
Metadata author:
Jessica R. Lacy
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Research Oceanographer
2885 Mission Street
Santa Cruz, CA

831-460-7520 (voice)
831-427-4748 (FAX)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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