Ultra-short baseline - navigation points and tracklines for Applied Acoustics EasyTrack Nexus 2 USBL data collected for ROV Global Explorer during USGS field activity 2017-001-FA.

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Frequently anticipated questions:

What does this data set describe?

Title:
Ultra-short baseline - navigation points and tracklines for Applied Acoustics EasyTrack Nexus 2 USBL data collected for ROV Global Explorer during USGS field activity 2017-001-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. Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-001-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, 20200409, Ultra-short baseline - navigation points and tracklines for Applied Acoustics EasyTrack Nexus 2 USBL data collected for ROV Global Explorer during USGS field activity 2017-001-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: -74.477562
    East_Bounding_Coordinate: -73.821625
    North_Bounding_Coordinate: 38.047653
    South_Bounding_Coordinate: 36.869959
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5e28b586e4b0d3f93b05fe2b/?name=2017-001-FA_ROVUSBLNav_browse.jpg (JPG)
    ROV USBL navigation trackline at Chincoteague Ridge.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 08-May-2017
    Ending_Date: 11-May-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 WGS 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    2017-001-FA_ROVUSBLNavPoints.shp
    ROV dive USBL point navigation shapefile for survey 2017-002-FA (1068 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.
    East
    Easting coordinate in UTM Zone 18 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:546562.92
    Maximum:603393.29
    Units:meters
    Resolution:.01
    North
    Northing coordinate in UTM Zone 18 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:4080574.37
    Maximum:4211757.48
    Units:meters
    Resolution:.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:-74.477562
    Maximum:-73.821625
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:36.869959
    Maximum:38.047653
    Units:degrees
    Resolution:1E-06
    DiveOp
    Name of the ROV dive represented by the trackline in the format: Dive # - Location (i.e.'Dive 3 - Norfolk East Arm'). (Source: U.S. Geological Survey) Character set
    Year
    Year the data were collected YYYY. (Source: U.S. Geological Survey) Character set
    JD_UTC
    Julian day and UTC time of navigation record 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
    WHCMSC 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
    RovID
    Remotely operated vehicle name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Ultra-short baseline device used to track the ROV. (Source: U.S. Geological Survey) Character set
    2017-001-FA_ROVUSBLTracklines.shp
    ROV dive USBL trackline navigation shapefile for survey 2017-001-FA (4 polyline 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.
    DiveOp
    Name of the ROV dive represented by the trackline in the format: Dive # - Location (i.e.'Dive 3 - Norfolk East Arm'). (Source: U.S. Geological Survey) Character set
    Year
    Calendar year the data were collected (Source: U.S. Geological Survey) Character set
    JDUTC_init
    Julian day and UTC time at the start of the ROV dive 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
    JDUTC_end
    Julian day and UTC time at the end of the ROV dive 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
    WHCMSC 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
    RovID
    Remotely operated vehicle name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Ultra-short baseline device used to track the ROV. (Source: U.S. Geological Survey) Character set
    Length_km
    Length of dive trackline in kilometers (UTM Zone 18N, WGS 84) calculated using XTools Pro. (Source: U.S. Geological Survey)
    Range of values
    Minimum:2.45
    Maximum:11.82
    Units:kilometers
    Resolution:0.01
    Entity_and_Attribute_Overview:
    Compilation of edited USBL point and trackline navigation for ROV Global Explorer dives conducted during USGS field activity 2017-001-FA.
    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?
    U.S. Geological Survey
    Attn: Wayne Baldwin
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

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

Why was the data set created?

This dataset contains point and trackline navigation data for four ROV Global Explorer dives tracked using an Applied Acoustics EasyTrack Nexus 2 ultra-short baseline system during USGS field activity 2017-001-FA along the U.S. Atlantic continental shelf break and upper continental slope between Baltimore and Keller Canyons. This information allows for spatial correlation of the video, photography, bathymetry, and geologic samples collected by the ROV during the dives with other geophysical data for investigating sea-floor ecology, chemistry, morphology, and stratigraphy in the area.

How was the data set created?

  1. From what previous works were the data drawn?
    SEG-Y SB-512i data (source 1 of 1)
    U.S. Geological Survey, unpublished material, HYPACK raw navigation.

    Type_of_Source_Media: disc
    Source_Contribution:
    The Applied Acoustics EasyTrack Nexus 2 USBL system was used to provide navigation for ROV Global Explorer dives during field activity 2017-001-FA. The system consisted of a hemispherical acoustic transceiver mounted in the rear slot of the retractable keel of the R/V Hugh R. Sharp, which is located approximately amidships on the center line of the vessel, and two 1100 series remote beacons mounted on the ROV main vehicle and controller pod, respectively. Ship navigation was initially supplied to the USBL system from the ships POS/MV inertial navigation system with intermittent success through May 4 (JD124) of 2017-001-FA, but for the remainder of the cruise ship navigation was supplied by a Hemisphere Differential GPS (DGPS) receiver with the DGPS antenna mounted on the aft 01 deck handrail approximately 3.4 meters aft and 4 meters to port of the USBL transceiver. While surveying, the retractable keel was lowered to 1-meter below the hull, resulting in a draft of 5.06 meters below the waterline. The EasyTrack Nexus 2 (version 2.0.2.1) software controlled the USBL system acquisition, logged the raw data stream (*.epb format), and output calculated bearing, slant range, depth, and position of the ROV vehicle relative to the ship (corrected for pitch, roll, and installation offsets) as an ORE Trackpoint 2EC string over a serial connection. HYPACK (version 2017, 17.1.3.0) survey software was used to monitor the serial connection using its 'Trackp.dll' driver, calculate the position of the ROV in WGS84, UTM 18 North, meters, and log the string transmitted from USBL system and the calculated position as messages in the HYPACK raw files. A network protocol time server was used to synchronize both the USBL and HYPACK acquisition computers to GPS time. Calibration procedures for the USBL system were conducted in the Delaware River estuary prior to conducting dives 3 - 5. Sound velocity profiles calculated from XBT casts were provided to the EasyTrack Nexus 2 software for use in range calculations.
  2. How were the data generated, processed, and modified?
    Date: May-2017 (process 1 of 4)
    PROCESS STEP 1:
    Unix shell programs were used to extract a subset of USBL position data and group the data by dive as follows:
    1)'grep' was used to extract all USBL ROV position messages from HYPACK raw files; the messages were piped to 'awk', which conditionally filtered the input to create a subset containing every fifth input message, converted the HYPACK time stamp (in seconds after midnight) to a fractional day value (divided by 86400 seconds/day), and printed the HYPACK time stamp, fractional day value, easting, and northing values to temporary output ASCII text files.
    2) 'cat' was used to concatenate all temporary text files for each dive into a single file per dive.
    Process steps 1 and 2 were conducted by Carolyn Ruppel. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Carolyn D. Ruppel
    Geophysicist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2339 (voice)
    (508) 457-2310 (FAX)
    cruppel@usgs.gov
    Date: May-2017 (process 2 of 4)
    PROCESS STEP 2: Microsoft Excel 2019, ArcMap (version 10.5), and XTools Pro (version 19) were used to edit and create point and trackline shapefiles from the individual dive ASCII text files:
    1) The ASCII text files for each dive were opened in Excel and the fractional day column was converted to hh:mm:ss time format in the process. Each file was saved to the comma separated values (CSV) format with headers for each column.
    2) Navigation data for each dive were imported from the CSV files into ArcMap (Add XY data) specifying WGS84, UTM 18 North as the coordinate system and saved to new point shapefiles.
    3) XTools Pro polylines from points was used to create a trackline shapefile from each new point shapefile using FID as the sort order field.
    4) Point and polyline shapefile pairs were examined together to evaluate the data for obviously erroneous navigation points (easily identified by impossibly large polyline deviations). Points identified as outliers were eliminated from the point shapefiles and after saving changes, the polylines from points operation was repeated to create a new dive trackline from the edited point data. In some instances this was an iterative process.
    5) The ArcMap data frame was reprojected from UTM 18N to WGS84 geographic coordinate system, then field names for longitude and latitude were added to the attribute tables of the point shapefiles and each were populated using calculate geometry in WGS84 geographic coordinates. Each point and polyline shapefile was exported to new geographic files using the coordinates of the data frame.
    Date: Jan-2020 (process 3 of 4)
    PROCESS STEP 3:
    XTools Pro and ArcMap (10.7.1) were used to modify the attribute tables of the geographic point and polyline shapefiles and merge them into one file each containing data for all the dives.
    1) XTools Pro modify table was used to delete (HYPACK time stamp), define and populate by expression (DiveOp, Year, JD_UTC, SurveyID, VehicleID, RovID, and DeviceID), and reorder fields in the individual dive point shapefile attribute tables. The resulting fields are "East, North, Lon, Lat, DiveOp, Year, JD_UTC, SurveyID, VehicleID, RovID, and DeviceID.
    2) ArcMap Merge was used to combine the point (with modified tables) and polyline shapefiles from each dive into a single file for each feature type; '2017-001-FA_ROVUSBLNavPoints.shp' and '2017-001-FA_ROVUSBLTracklines.shp', respectively.
    3) XTools Pro modify table was used to define the fields "DiveOp, Year, JDUTC_init, JDUTC_end, SurveyID, VehicleID, RovID, and DeviceID" in the attribute table of '2017-001-FA_ROVUSBLTracklines.shp'. The field s "Year, SurveyID, VehicleID, RovID, and DeviceID" were populated by expression using the field calculator, and "DiveOp, JDUTC_init, JDUTC_end" were populated by hand with values copied from the attribute tables of the individual dive point shapefiles.
    4) XTools Pro calculate geometry was used to create the field "Length_km" in the attribute table of '2017-001-FA_ROVUSBLTracklines.shp' and populate it with the lengths of each polyline feature in the file calculated in WGS84, UTM 18 North, kilometers. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Wayne E. Baldwin
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

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

    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?
    Ship navigation was supplied to the Applied Acoustics EasyTrack Nexus 2 USBL system from the ships POS/MV inertial navigation system with intermittent success through May 4 (JD124) of 2017-001-FA, but for the remainder of the cruise ship navigation was supplied by a Hemisphere GPS receiver with the GPS antenna mounted on the aft 01 deck handrail approximately 3.4 meters aft and 4 meters to port of the USBL transceiver. The USBL acoustic transceiver was mounted in the rear slot of the retractable keel of the R/V Hugh R. Sharp, which is located approximately amidships on the center line of the vessel, and two 1100 series remote beacons mounted on the ROV main vehicle and controller pod, respectively. The USBL system calculated the bearing and slant range between the transceiver and remote beacons, as well as depths and positions of the beacons relative to the ship, corrected for pitch, roll, and installation offsets. HYPACK calculated the final positions of the ROV vehicle by applying the computed relative offsets to ship positions at corresponding UTC times. GPS horizontal positional accuracy is assumed to be within 3 m and accuracy of the positions and bearings can be up to 0.12 percent of the slant range and 0.01 degrees, respectively. After filtering the calculated positions (see description in the processing steps below) to remove scatter of up to a kilometer outside of the dive area footprints, the accuracy of the remaining positions are estimated to be within 50 meters. Factors possibly contributing to uncertainties in the calculated positions include calibration of the system in an environment considerably different from the survey area (estuary versus offshore), inadequate characterization of water column sound speeds, or acoustic interference from other water column noise sources (multipath interference, bubble wash beneath the ships keel, interference with the concurrently operated split-beam sonar).
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    USBL navigation was not available during the first offshore dive of the field activity at Washington Canyon on May 4, 2017 (JD124) due to inoperability of the USBL system. Additionally, USBL navigation collected during the second dive within the Delaware River estuary on May 7, 2017 (JD127) for system troubleshooting is not included in the data release.
  5. How consistent are the relationships among the observations, including topology?
    ROV dives tracked using the USBL navigation system were conducted during daytime operations (generally between approximately 10:00 and 23:00 UTC) on May 8-11 (JD128 - JD130), 2017. Navigation for four dives, numbered 3-6 are included in the shapefiles '2017-001-FA_ROVUSBLNavPoints.shp' and '2017-001-FA_ROVUSBLTracklines'.

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
    Denver Federal Center
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? USGS data release of USBL point and trackline navigation for ROV Global Explorer dives conducted along the U.S. Atlantic continental shelf break and upper slope between Baltimore and Keller Canyons during USGS field activity 2017-001-FA: includes '2017-001-FA_ROVUSBLNavPoints.shp' containing the edited point navigation features, '2017-001-FA_ROVUSBLTracklines.shp' containing the trackline features, the browse graphic 2017-001-FA_ROVUSBLNav_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file '2017-002-FA_ROVUSBLNav_meta.xml'. These datasets can be downloaded individually or packaged on-demand in a zip file (see the Digital Transfer Option section).
  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.

Who wrote the metadata?

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

(508) 548-8700 x2226 (voice)
(508) 457-2310 (FAX)
wbaldwin@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
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