Sound velocity profiles - locations, images, and text files for sound velocity profiles calculated from XBT and CTD casts conducted during USGS field activities 2017-001-FA and 2017-002 FA.

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Frequently anticipated questions:


What does this data set describe?

Title:
Sound velocity profiles - locations, images, and text files for sound velocity profiles calculated from XBT and CTD casts conducted during USGS field activities 2017-001-FA and 2017-002 FA.
Abstract:
In spring and summer 2017, the U.S. Geological Survey’s Gas Hydrates Project conducted two cruises aboard the research vessel Hugh R. Sharp to explore the geology, chemistry, ecology, physics, and oceanography of sea-floor methane seeps and water column gas plumes on the northern U.S. Atlantic margin between the Baltimore and Keller Canyons. Split-beam and multibeam echo sounders and a chirp subbottom profiler were deployed during the cruises to map water column backscatter, sea-floor bathymetry and backscatter, and subsurface stratigraphy associated with known and undiscovered sea-floor methane seeps. The first cruise, known as the Interagency Mission for Methane Research on Seafloor Seeps and designated as field activity 2017-001-FA, was conducted from May 4 to May 11, 2017, and acquired geophysical data to support remotely operated vehicle exploration of seep sites using the Global Explorer, which is operated by Oceaneering International, Inc. Geophysical operations during cruise 2017-002-FA from August 25 to September 6, 2017, were also focused on mapping water column methane plumes, sea-floor seep sites, and subseafloor strata, but primarily supported conductivity, temperature, and depth instrument deployment, surface-water methane-concentration mapping, and water-sampling operations as part of a collaborative study with the University of Rochester of the effect of methane seepage on ocean water biogeochemistry. The National Oceanic and Atmospheric Administration’s Office of Ocean Exploration and Research partially sponsored cruise 2017-001-FA, and the U.S. Department of Energy partially sponsored both cruises.
Supplemental_Information:
Support for 2017-001-FA was provided to the USGS by NOAA and DOE through interagency agreements 16-01118 and DE-FE0023495, respectively. Support for 2017-002-FA was provided to the USGS and the University of Rochester by DOE through interagency agreement DE-FE0026195 and grant DE-FE0028980, respectively. Additional information on the field activities are available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-001-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-002-FA. Additional information specific to the Interagency Mission for Methane Research on Seafloor Seeps is available at https://www.usgs.gov/centers/whcmsc/science/immerss-interagency-mission-methane-research-seafloor-seeps?qt-science_center_objects=0#qt-science_center_objects and https://archive.usgs.gov/archive/sites/soundwaves.usgs.gov/2017/05/outreach.html.
  1. How might this data set be cited?
    U.S. Geological Survey, 2020, Sound velocity profiles - locations, images, and text files for sound velocity profiles calculated from XBT and CTD casts conducted during USGS field activities 2017-001-FA and 2017-002 FA.: data release DOI:10.5066/P9Y1MSTN, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Baldwin, Wayne E., Moore, Eric M., Worley, Charles R., Nichols, Alex R., and Ruppel, Carolyn D., 2020, Marine Geophysical Data Collected to Support Methane Seep Research Along the U.S. Atlantic Continental Shelf Break and Upper Continental Slope Between the Baltimore and Keller Canyons During U.S. Geological Survey Field Activities 2017-001-FA and 2017-002-FA.: data release DOI:10.5066/P9Y1MSTN, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Baldwin, W.E., Moore, E.M., Worley, C.R., Nichols, A.R., and Ruppel, C.D., 2020, Marine Geophysical Data Collected to Support Methane Seep Research Along the U.S. Atlantic Continental Shelf Break and Upper Continental Slope Between the Baltimore and Keller Canyons During U.S. Geological Survey Field Activities 2017-001-FA and 2017-002-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9Y1MSTN.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.777222
    East_Bounding_Coordinate: -74.070000
    North_Bounding_Coordinate: 37.813333
    South_Bounding_Coordinate: 35.296667
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5e1e05d7e4b0ecf25c610cc2/?name=2017-001-FA_2017-002-FA_SVPdata_browse.jpg (JPG)
    Example SVP profile image.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 04-May-2017
    Ending_Date: 05-Sep-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the 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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    2017-001-FA_2017-002-FA_SVPdata.shp
    Sound velocity profile location shapefile for surveys 2017-001-FA and 2017-002-FA (51 point features). (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    Lon
    Decimal degree longitude value in GCS WGS 84. (Source: U.S. Geological Survey)
    Range of values
    Minimum:-75.777222
    Maximum:-74.07
    Units:degrees
    Resolution:.000001
    Lat
    Decimal degree latitude value in GCS WGS 84. (Source: U.S. Geological Survey)
    Range of values
    Minimum:35.296667
    Maximum:37.813333
    Units:degrees
    Resolution:.000001
    SVP
    Name of sound velocity profile used to distinguish between casts. Profile names containing 'XBT' refer to the Sippican XBT casts, and those containing 'CTD' refer to Seabird Electronics 911plus CTD casts (in names for XBT casts, the probe type is prepended to 'XBT'; the last two digits in each XBT and CTD casts indicates sequential cast number.) (Source: U.S. Geological Survey) character set
    Date
    mm/dd/yyyy when the SVP cast was collected. (Source: U.S. Geological Survey) character set
    JD_UTC
    Julian day and UTC time when the SVP cast was collected in the format: JD:HH:MM:SS; Julian day is the integer number (although recorded here in text string format) representing the interval of time in days since January 1 of the year of collection. (Source: U.S. Geological Survey) character set
    SurveyID
    WHMSC field activity identifier (e.g. "2017-001-FA" where 2017 is the survey year, 001 is survey number of that year, and FA is field activity). (Source: U.S. Geological Survey) character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) character set
    DeviceID
    Device used to collect sound speed profile data. (Source: U.S. Geological Survey) character set
    SVP_Image
    Name of the PNG image file associated with the SVP cast. (Source: U.S. Geological Survey) Character set
    2017-001-FA_2017-002-FA_SVP_ASCII
    Sound velocity profile data in Caris SVP (.svp) ASCII format for surveys 2017-001-FA and 2017-002-FA (51 SVP files) (Source: U.S. Geological Survey)
    2017-001-FA_2017-002-FA_SVP_Images
    Portable network graphic images of sound velocity profile data for surveys 2017-001-FA and 2017-002-FA (51 PNG files) (Source: U.S. Geological Survey)
    Entity_and_Attribute_Overview:
    The PNG images can be hyperlinked to their shapefile location in ArcGIS. The graphs show depth on the y-axis and speed of sound on the x-axis. In addition to the graphs, the SVP data is also available in Caris .svp formatted ASCII files. The format of the .svp files is as follows:
    Header row1: [SVP_VERSION_2] (format version number) Header row2: 2017-001-FA_T4XBT01.svp (cast file name) Header row3: Section 2017-237 23:42:54 37:31:48 -74:18:36 (Caris Section header indicating Year-Day, UTC Time, Degree:Minute:Second Latitude, and Degree:Minute:Second Longitude of cast) Remaining rows: column data of depth (meters) and speed of sound (meters per second) space delimited.
    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)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

Why was the data set created?

This dataset is used to display the locations of sound velocity profiles (SVP, also referred to as sound speed profiles), as well as the SVP data, collected using Sippican XBT probes and a Seabird Electronics 911plus CTD during two 2017 USGS cruises along the U.S. Atlantic continental shelf break and upper continental slope between Accomac and Keller Canyons. The sound velocity profiles document water column sound speed variability during the cruises, and were used during processing to account for refraction artifacts present within the multibeam bathymetric data. The dataset contains graphs of the sound velocity profile at each station, as well as the date of collection, time of day, and station location coordinates in Geographic Coordinate System (GCS) WGS 84 latitude and longitude.

How was the data set created?

  1. From what previous works were the data drawn?
    XBT and CTD profile data (source 1 of 1)
    U.S. Geological Survey, unpublished material, XBT and CTD profile data.

    Type_of_Source_Media: disc
    Source_Contribution:
    A Sippican XBT system consisting of a hand launcher connected via cable to an MK21 processing unit was used to launch Sippican T4 and T5 XBT probes (maximum depths of 460 and 1830 m, respectively) from the center stern of the vessel, and WinMK21 (version 7.1) acquisition software logged the temperature and depth data during each deployment. GPS navigation data for the sound velocity profiles were acquired using the WGS 84 coordinate system with a Hemisphere GPS receiver. XBTs were launched from the center of the stern, ~ 16 m aft of the GPS antenna mounted on the aft 01 deck handrail and the positional offset was not accounted for. A HYPACK (v. 17.0.26.0) target was created to record the position of each SVP station, and the geographic coordinates were manually entered into the WinMK21 (version 7.1) acquisition software as casts were conducted. CTD data were collected using an SBE 911plus CTD system, consisting of a 9plus CTD unit deployed from the CTD winch station located on the starboard side approximately amidships, with data transferred via the winch wire through a slip ring, and logged by an 11plus deck unit and Seabird Seasave (version 7.26.7) acquisition software in real time. Navigation for the CTD casts was provided by the vessel's Furuno GP-37 DGPS and logged to the raw data header.
  2. How were the data generated, processed, and modified?
    Date: Sep-2017 (process 1 of 4)
    XBT and CTD deployment and data and processing at sea:
    During 2017-001-FA and 2017-002-FA XBT probes were generally deployed at the start and end of each overnight geophysical watch and intermittently when the multibeam bathymetric data were substantially impacted by sound speed related refraction artifacts. The Raw XBT EDF files recorded by the WinMK21 (version 7.1) acquisition software were imported into SVPEditor (version 1.0.5), which calculated a sound velocity profile via the UNESCO equation (Fofonoff and Millard, 1983) using the temperature profile data and a synthetic salinity profile estimated from World Ocean Atlas (2009) data at the location of the cast. The resulting sound velocity profiles were exported in Caris .svp and HYPACK .vel formatted ASCII files. CTD casts were primarily performed during daytime operations of 2017-002-FA only. R/V Sharp technicians used Seabird Seasave (version 7.26.7) to acquire and process the raw CTD HEX data, with one of the resulting outputs being a .sv_csv sound velocity profile for the downward portion of the cast, also calculated using the UNESCO equation. A python script was used to extract the time and position for the start of the cast from the processed .csv file, and the processed depth and sound velocity columns from the .sv_csv file and save them to a Caris .svp formatted ASCII file. (Fofonoff, N.P. and Millard Jr, R.C. (1983) Algorithms for the computation of fundamental properties of seawater. Paris, France, UNESCO, 53pp. (UNESCO Technical Papers in Marine Sciences; 44), http://hdl.handle.net/11329/109)
    This process step and all subsequent process steps were conducted by the same person - Wayne Baldwin. Person who carried out this activity:
    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2226 (voice)
    (508) 457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2019 (process 2 of 4)
    Plot the SVP data and import into SpatiaLite database:
    A python script was used to read the SVP data and plot the sound speed profile as speed of sound (meter/second) versus depth (meters). Position, date, and time were pulled from the SVP header and written into the image (PNG) for reference. Within the same script, the position, Julian day, time, and profile id were also imported into a SpatiaLite (version 4.3.0) enabled SQLite (version 3.26.0) database table. The geographic positions were used to create point geometries for the station locations, and additional fields indicating Survey_ID, Vessel_ID, Device_ID, and SVP_Image were added.
    Date: Oct-2019 (process 3 of 4)
    Create Esri shapefile containing the point data:
    The SVP point features were added (Add Data) into ArcMap (version 10.7.1) from the SQLite database, then exported (Right click on database feature class > Data > Export Data) to the new Esri point shapefile '2017-001-FA_2017-002-0FA_SVPdata.shp'.
    Date: 06-Aug-2020 (process 4 of 4)
    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
  3. What similar or related data should the user be aware of?
    Demopoulos, A., McClain-Counts, J., Bourque, J., Prouty, N., Smith, B., Brooke, S., Ross, S., and Ruppel, C., 2019, Examination of Bathymodiolus childressi nutritional sources, isotopic niches, and food-web linkages at two seeps in the US Atlantic margin using stable isotope analysis and mixing models.: Deep Sea Research Part I 148, pp.53-66, Elsevier, Amsterdam, Netherlands.

    Online Links:

    Leonte, M., Ruppel, C. D., Ruiz‐Angulo, A., and Kessler, J. D., 2020, Surface methane concentrations along the Mid‐Atlantic Bight driven by aerobic subsurface production rather than seafloor gas seeps.: Journal of Geophysical Research: Oceans vol. 125, American Geophysical Union Publications, Washington, DC.

    Online Links:

    Leonte, M., Ruppel, C. D., Ruiz‐Angulo, A., and Kessler, J. D., 2020, Water temperature, salinity, methane, methane stable isotopes, and others chemical parameters collected by CTD and Niskin bottles from research vessel Hugh R. Sharp in Mid-Atlantic Bight from 2017-08-25 to 2017-09-05.: NOAA National Centers for Environmental Information Dataset NCEI Accession 0209090, NOAA National Centers for Environmental Information, Boulder, CO.

    Online Links:

    Ruppel, C., Demopoulos, A., and Prouty, N., 2018, Exploring US Mid-Atlantic Margin Methane Seeps: IMMeRSS, May 2017.: Supplement to Oceanography 31(1), p.93, The Oceanography Society, Rockville, MD.

    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?
    Navigation for the XBT casts was provided using a Hemisphere GPS receiver. XBTs were launched from the center of the stern, ~ 16 m aft of the GPS antenna mounted on the aft 01 deck handrail and the positional offset was not accounted for. A HYPACK (v. 17.0.26.0) target was created to record the position of each SVP station, and the geographic coordinates were manually entered into the WinMK21 (version 7.1) acquisition software as casts were conducted. Navigation for the CTD casts was provided by the vessel's Furuno GP-37 GPS and logged to the raw data header. CTD operations were conducted from the CTD winch station located on the starboard side approximately amidships. While the horizontal position accuracy is thought to be within 3 meters for the GPS position solutions, we consider the positions for the XBT casts to be within approximately 20 m, since the offset to the stern launch position was not accounted for. Reported positions represent locations at the start of each cast.
  3. How accurate are the heights or depths?
    XBTs depths are estimated as a function of time after deployment via fall-rate equations by the WinMK21 (version 7.1) acquisition software and derived depths are accurate to within 2 percent of the water depth. SBE 911plus CTD depths are estimated by the Seabird Seasave (version 7.26.7) acquisition software via a calculation converting pressure sensor readings to depths while taking into account sea water density and gravity as a function of latitude, and the depths are thought to be accurate to within 1 meter.
  4. Where are the gaps in the data? What is missing?
    Each sound velocity profile (51 total) collected during cruises 2017-001-FA and 2017-002-FA is represented by a Caris .svp formatted ASCII text file (see description below in the entity and attribute overview section), a PNG image file, and a feature point location in '2017-001-FA_2017-002-FA_SVPdata.shp'.
  5. How consistent are the relationships among the observations, including topology?
    Sound velocity profiles were calculated from either Sippican Expendable Bathythermograph (XBT, T4 or T5 types) probe temperature and depth data or Seabird Electronics (SBE) 911plus conductivity, temperature, and depth (CTD) cast data. XBT probes were primarily launched during overnight geophysical mapping operations on both cruises, while CTD casts were conducted during daytime operations on 2017-002-FA only. 2017-001-FA_T4XBT01, 2017-001-FA_T4XBT05, 2017-001-FA_T4XBT07, and 2017-002-FA_T4XBT01 do not coincide with a trackline in '2017-001-FA_2017-002-FA_7160Tracklines.shp' or '2017-001-FA_2017-002-FA_EK60Tracklines' because the casts were conducted either prior to the start of geophysical survey operations or after they were completed. The approximately 11 meter profile for cast 2017-002-FA_CTD08 represents a test deployment of the CTD system in the Delaware River estuary.

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:
Public domain data from the U.S. Government are freely distributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Federal Center
    Denver, CO

    1-888-275-8747 (voice)
  2. What's the catalog number I need to order this data set? USGS data release of sound velocity profiles collected along the U.S. Atlantic continental shelf break and upper slope between Accomac and Keller Canyons during USGS field activities 2017-001-FA and 2017-002-FA: includes the shapefile '2017-001-FA_2017-002-FA_SVPdata.shp', the zip archive '2017-001-FA_2017-002-FA_SVP_Images.zip' containing 51 PNG images that represent all sound velocity profiles graphically, the zip archive '2017-001-FA_2017-002-FA_SVP_ASCII.zip' containing 51 Caris .svp formatted ASCII files, the browse graphic '2017-001-FA_2017-002-FA_SVPdata_browse.jpg', and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file '2017-001-FA_2017-002-FA_SVPdata_meta.xml'.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    To utilize these data, the user must have software capable of reading shapefiles, ASCII text, and/or PNG images.

Who wrote the metadata?

Dates:
Last modified: 06-Aug-2020
Metadata author:
Wayne E. Baldwin
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2226 (voice)
(508) 457-2310 (FAX)
wbaldwin@usgs.gov
Metadata standard:
fgdc content standards for digital geospatial metadata (FGDC-STD-001-1998)

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