Oceanographic and Water-Quality Measurements-- Blackwater National Wildlife Refuge, Maryland, 2011 (EPIC) (ver. 1.1, September 2015)

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Frequently anticipated questions:

What does this data set describe?

Title:
Oceanographic and Water-Quality Measurements-- Blackwater National Wildlife Refuge, Maryland, 2011 (EPIC) (ver. 1.1, September 2015)
Abstract:
Suspended-sediment transport is a critical element governing the geomorphology of tidal marshes. Marshes rely both on organic material and inorganic sediment deposition to maintain their elevation relative to sea-level. In wetlands near the Blackwater National Wildlife Refuge, MD, portions of the salt marsh have been subsiding relative to sea level since the early 20th century. Other portions of the marsh have been successful at maintaining elevation. The USGS undertook measurements of suspended-sediment concentration in the tidal channels in order to understand the magnitude of suspended-sediment concentrations, the sediment-transport mechanisms, and relative differences between the two areas of the marsh. We deployed optical turbidity sensors and acoustic velocity meters at multiple sites over two periods in 2011. The time-series of oceanographic data collected during those field studies, including velocity, depth, turbidity, salinity, water temperature, and pH are presented here. For more information on the field operations associated with data collection: https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-017-FA; https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-029-FA; https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-044-FA; https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-050-FA.
The originally-processed, authoritative netCDF data files are provided in Equatorial Pacific Information Collection (EPIC) metadata convention, which has since been retired. A translated version is also available in the currently-used Climate and Forecast (CF) metadata convention. The primary difference between the two conventions is that EPIC has two time variables to represent Julian Day and milliseconds, while CF only has one time variable. Additionally, burst data and some waves files were not converted to CF due to the inability to handle 2D time with multidimensional variables. Therefore, the CF files may not represent all the data files released. Files may be downloaded or accessed using the Open-source Project for a Network Data Access Protocol (OPeNDAP) or via Thematic Realtime Environmental Distributed Data Services (THREDDS).
  1. How might this data set be cited?
    Ganju, Neil K., Dickhudt, Patrick J., Montgomery, Ellyn T., Brennand, Patrick, Derby, R. Kyle, Brooks, Thomas W., Martini, Marinna A., Borden, Jonathan, and Baldwin, Sandy, 20260506, Oceanographic and Water-Quality Measurements-- Blackwater National Wildlife Refuge, Maryland, 2011 (EPIC) (ver. 1.1, September 2015): data release DOI:10.5066/P14HXWKQ, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Ganju, Neil K., Dickhudt, Patrick J., Montgomery, Ellyn T., Brennand, Patrick, Derby, R. Kyle, Brooks, Thomas W., Martini, Marinna A., Borden, Jonathan, and Baldwin, Sandy, 2012, Oceanographic and Water-Quality Measurements-- Blackwater National Wildlife Refuge, Maryland, 2011 (ver. 1.1, September 2015): data release DOI:10.5066/P14HXWKQ, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    Ganju, N.K., Dickhudt, P.J., Montgomery, E.T., Brennand, P., Derby, R.K, Brooks, T.W., Martini, M.A., Borden, J., and Baldwin, S., 2012, Oceanographic and Water-Quality Measurements-- Blackwater National Wildlife Refuge, Maryland, 2011 (ver. 1.1, September 2015): U.S. Geological Survey data release, https://doi.org/10.5066/P14HXWKQ.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.1
    East_Bounding_Coordinate: -75.95
    North_Bounding_Coordinate: +38.425
    South_Bounding_Coordinate: +38.35
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: Mar-2011
    Ending_Date: Dec-2011
    Currentness_Reference:
    ground condition of data collection; data were not collected during the entire span of dates. See the sampling interval link for specific start and end dates for each instrument.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: netCDF
  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?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    9031ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9041ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9051ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9061ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9071ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9081ysi-a.nc; instrument: YSI model 6920; variables: conductivity, pH, salinity, temperature, turbidity 9151ysi-a.nc; instrument: YSI model 6600; variables: conductivity, oxygen, salinity, temperature, turbidity 9152aqd-a.nc; instrument: Nortek Aquadopp Profiler; variables: currents, pressure, sound velocity, temperature 9161ysi-a.nc; instrument: YSI model 6600; variables: conductivity, oxygen, salinity, temperature, turbidity 9162aqd-a.nc; instrument: Nortek Aquadopp Profiler; variables: currents, pressure, sound velocity, temperature 9171eco-a.nc; instrument: Wetlabs ECO BBSB; variables: turbidity 9181eco-a.nc; instrument: Wetlabs ECO BBSB; variables: turbidity
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the metadata contact person, unless otherwise noted. 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)
    • Neil K. Ganju
    • Patrick J. Dickhudt
    • Ellyn T. Montgomery
    • Patrick Brennand
    • R. Kyle Derby
    • Thomas W. Brooks
    • Marinna A. Martini
    • Jonathan Borden
    • Sandy Baldwin
  2. Who also contributed to the data set?
    Funding was provided by the U.S. Geological Survey Coastal and Marine Geology Program and Global Climate Change Program.
  3. To whom should users address questions about the data?
    Neil K. Ganju
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    United States

    (508) 457-8700 x2252 (voice)
    nganju@usgs.gov

Why was the data set created?

This dataset in EPIC convention provides measurements from an estuarine field study that occurred in the spring and fall of 2011. The data were collected in support of efforts to model the circulation, nutrient and sediment fluxes in the marsh. The background and experimental setup are described in the open file report "Summary of Oceanographic and Water-Quality Measurements near the Blackwater National Wildlife Refuge, 2011", https://pubs.usgs.gov/of/2012/1099/. The basic sampling interval data files are provided at the rate at which the sensor made observations- no temporal averaging, filtering or subsampling was done. The data files are accessible by clicking the file name.

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: 2012 (process 1 of 7)
    FIELD PROGRAM: Between March and May 2011, continuous measurements were collected at three sites in the Blackwater complex (moorings 903, 904, 905) and three sites in the Fishing Bay complex (moorings 906, 907,908). Identical pole-mounted YSI sensors were deployed at all six sites. Parameters measured include water level, salinity, temperature, dissolved Oxygen, pH, and turbidity. Between September and October 2011, continuous measurements were collected at two sites in the Blackwater complex (moorings 916, 917) and two sites in the Fishing Bay complex (moorings 915, 918). A pole-mounted YSI and an upward looking current profiler were deployed at sites 915 and 916, with a pole-mounted turbidity sensor deployed at 917 and 918. Parameters measured include water level, water velocity, salinity, temperature, dissolved Oxygen, and turbidity.
    Date: 2012 (process 2 of 7)
    DATA PROCESSING: Data processing was conducted using the proprietary software for each instrument, and (or) specialized software developed by the USGS. The proprietary software was often used to download data from the instruments and export the data to ASCII-files. Post-processing of the raw binary or ASCII files was accomplished using USGS software developed in the MATLAB (http://www.mathworks.com/) programming language. As part of the processing, instrument-specific formats were converted to the EPIC-standard NetCDF format (http://www.pmel.noaa.gov/epic/) and scientific units. Data were carefully checked for inconsistencies, time drift, and other problems and then edited if needed. The beginning and end of each data series were truncated to remove data collected out of water. After final editing, the best basic version of the data file that includes all variables recorded at the basic sampling interval (the fastest rate at which the sensor sampled) is published. Person who carried out this activity:
    Ellyn Montgomery
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    United States

    508-457-8700 x2356 (voice)
    emontgomery@usgs.gov
    Date: 12-Jul-2016 (process 3 of 7)
    Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Added online link to experiment page. Fixed online link to cross-reference. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 4 of 7)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 31-Jan-2019 (process 5 of 7)
    Fixed broken links. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 6 of 7)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 06-Mar-2026 (process 7 of 7)
    In 2026, this data release was migrated from the server https://stellwagen.er.usgs.gov/ to the Coastal and Marine Hazards and Resources Program Trusted Digital Repository (CMGDS) via the Data Release Builder. This move was part of a larger effort to consolidate websites and reduce the number of sub-domains within the U.S. Geological Survey. The existing metadata was updated to conform to current standards. The data themselves met the standards at the time of initial release to the public. Specific edits for the metadata include but are not limited to: updating the Network Resource links to point to the new location of the data, updating various elements (Use Constraints, Access Constraints, Distribution Liability) to conform to today’s standards, updating the citation, and adding USGS Thesaurus keywords, edition, geoform, data series, data issue, supplemental information, entity and attribute overview, and horizontal and vertical datums. Additionally, a shapefile was created from the originally released KML file to document data location. Person who carried out this activity:
    Olivia A. De Meo
    U.S. Geological Survey, Northeast Region
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2356 (voice)
    whsc_data_contact@usgs.gov
    Contact_Instructions:
    The contact email address is a generic address in the event the person is no longer with USGS.
  3. What similar or related data should the user be aware of?
    Montgomery, E.T., Martini, M.A., Lightsom, F.L., and Butman, Bradford, 2008, Documentation of the U.S. Geological Survey Oceanographic Time Series Measurement Database: Open-File Report 2007-1194, U.S. Geological Survey, Reston, VA.

    Online Links:

    Ganju, N.K., Dickhudt, P.J., Montgomery, E.T., Brennand, P., Derby, R.K., Brooks, T.W., Martini, M.A., Borden, J., and Baldwin, S., 2011, Summary of Oceanographic and Water-Quality Measurements near the Blackwater National Wildlife Refuge, 2011: Open-File Report 2012-1099, U.S. Geological Survey, Reston, VA.

    Online Links:

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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    The deployment locations were measured by a hand-held GPS (Garmin GPS C76).
  3. How accurate are the heights or depths?
    The sensors were mounted on poles or the channel bottomin less than 5 meters of water. The tidal range here is ~0.5 meters so as the tide changes, so will the relative depth. Height above the bottom will not change and be accurate to within 5 cm, while depth may change significantly.
  4. Where are the gaps in the data? What is missing?
    The data have been edited to remove outlying points and data recorded when the instruments were out of the water (before and after deployment or at low tide).
  5. How consistent are the relationships among the observations, including topology?
    Data are logically consistent

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. Please see 'Distribution Information' for details.
Use_Constraints These data are marked with a Creative Commons Zero v1.0 Universal (CC0-1.0) public domain dedication and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. 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)
    Neil K. Ganju
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 457-8700 x2252 (voice)
    stellwagen_manager@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable data in self-describing netCDF files and metadata as xml and text formats.
  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 user's computer must have software to read netCDF files or import OPeNDAP.

Who wrote the metadata?

Dates:
Last modified: 06-May-2026
Metadata author:
Ellyn T. Montgomery
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
United States

(508) 457-8700 x2356 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the metadata contact is no longer with the USGS or the email is otherwise invalid.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/DRB_data_release/DRB_P14HXWKQ/BW2011_meta_EPIC.faq.html>
Generated by mp version 2.9.51 on Tue May 12 10:49:49 2026