Bathymetry tracklines collected in the Belfast Bay, Maine pockmark field using a SWATHplus-M interferometric sonar in 2006 and 2008, by the U.S. Geological Survey (Esri polyline shapefile, WGS 84)

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Frequently anticipated questions:

What does this data set describe?

Bathymetry tracklines collected in the Belfast Bay, Maine pockmark field using a SWATHplus-M interferometric sonar in 2006 and 2008, by the U.S. Geological Survey (Esri polyline shapefile, WGS 84)
The U.S. Geological Survey, Woods Hole Coastal and Marine Science Center in cooperation with the University of Maine mapped approximately 50 square kilometers of the seafloor within Belfast Bay, Maine. Three geophysical surveys conducted in 2006, 2008 and 2009 collected swath bathymetric (2006 and 2008) and chirp seismic reflection profile data (2006 and 2009). The project characterized the spatial, morphological and subsurface variability of the Belfast Bay, Maine pockmark field. Pockmarks are large seafloor depressions that are associated with seabed fluid escape.
These data were collected during three separate surveys: Field Activity 2006-024-FA, 12-17 Sept, 2006 Field Activity 2008-024-FA, 17-24 Sept, 2008 Field Activity 2009-037-FA, 27-30 July, 2009 The EdgeTech 424 seismic system became inoperable at the beginning of survey 2008-024-FA, although the survey continued collecting interferometric and sidescan sonar data. The third survey in 2009 (2009-037-FA) was conducted to collect just seismic data that was not collected during 2008-024-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 20201210, Bathymetry tracklines collected in the Belfast Bay, Maine pockmark field using a SWATHplus-M interferometric sonar in 2006 and 2008, by the U.S. Geological Survey (Esri polyline shapefile, WGS 84): data release DOI:10.5066/P90QQCOR, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Andrews, Brian D., Danforth, William W., Brothers, Laura L., and Barnhardt, Walter A., 2020, High-resolution geophysical data collected in the Belfast Bay, Maine pockmark field in 2006, 2008, and 2009 by the U.S. Geological Survey: data release DOI:10.5066/P90QQCOR, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Suggested citation: Andrews, B.D., Danforth, W. W., Brothers, L.L., Barnhardt, W. A., 2020, High-resolution geophysical data collected in the Belfast Bay, Maine Pockmark Field in 2006, 2008, and 2009 by the U.S. Geological Survey: U.S. Geological Survey data release,
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -68.968449
    East_Bounding_Coordinate: -68.879549
    North_Bounding_Coordinate: 44.431989
    South_Bounding_Coordinate: 44.309543
  3. What does it look like? (JPG)
    Thumbnail image of bathymetry tracklines collected in Belfast Bay, Maine.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Sep-2006
    Ending_Date: 27-Sep-2008
    Bathymetry data were collected on the following dates: 20060912-20060917 (Julian day 255-260); 20080924-20080927 (Julian day 261-268).
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a vector data set. It contains the following vector data types (SDTS terminology):
      • string (166)
    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?
    Bathymetry tracklines for surveys 2006-024-FA and 2008-024-FA. (Source: U.S. Geological Survey)
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Feature geometry. (Source: Esri) Coordinates defining the features.
    Julian day the line was collected representing the interval of time in days since January 1 of the year of collection. (Source: U.S. Geological Survey) Character set
    Name of the trackline along which SWATHplus-M data were collected in the format: LineNumberFileNumber (i.e.'L1F1') (Source: U.S. Geological Survey) Character set
    Length of SWATHplus-M data line in kilometers (UTM Zone 19N, WGS 84) calculated using ArcGIS Pro. (Source: U.S. Geological Survey)
    Range of values
    WHCMSC field activity identifier (e.g. "2006-024-FA" where 2006 is the survey year, 024 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    Sonar device used to collect bathymetry data. (Source: U.S. Geological Survey) Character set
    This shapefile with attributes provide a record of all bathymetric files collected in the Belfast Bay survey area.
    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?
    Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  3. To whom should users address questions about the data?
    Brian Andrews
    U.S. Geological Survey
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)

Why was the data set created?

This bathymetric dataset was collected to understand the morphology of the pockmark field in Belfast Bay, Maine. This polyline shapefile records the line names and dates of each of the bathymetric tracklines collected for this project.

How was the data set created?

  1. From what previous works were the data drawn?
    SWATHplus-M echo sounder data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw SWATHplus-M data in .sxr format.

    Type_of_Source_Media: disc
    SONAR CONFIGURATION: Bathymetry data were collected using a Systems Engineering and Assessment Ltd. (SEA) SWATHplus-M interferometric sonar operating at a frequency of 234 kHz. The sonar transducers were mounted on a rigid pole installed on the bow of the RV Rafael and were deployed at a depth of 0.7m below the water line while collecting data. Typical sonar operating parameters include a transmit power of 9, transmit length of 28 cycles, 20148 samples per channel and a 100-meter range.
    A motion reference unit (TSS Ltd.) Dynamic Motion Sensor (DMS) was mounted directly above the transducers and continuously measured vertical displacement (heave), and attitude (pitch and roll) of the survey vessel during data acquisition. Data were recorded to SWATHplus-M raw format (*.sxr) using Swath Processor software. Sound-velocity profiles were collected approximately every 2 hours during the survey using a hand-casted Applied Microsystems SV Plus sound velocimeter. Real-time Kinematic Global Positioning System (RTK-GPS) navigation was used to determine the horizontal and vertical position (x,y,z) of the GPS antenna with sub-meter accuracy mounted on top of the pole. The RTK-DGPS coordinates were transmitted to the survey vessel from a land-based RTK-DGPS station established by the USGS over National Ocean Service (NOS) monument 5191-A Belfast, Penobscot Bay, Maine
  2. How were the data generated, processed, and modified?
    Date: Sep-2008 (process 1 of 6)
    Note: Processing steps 1-3 described here are the same for both of the surveys that collected bathymetry (2006-024-FA, and 2008-024-FA)the processing date reflects the most recent (2008) date.
    Depths were corrected to Mean Lower Low Water (MLLW) using 1 second RTK-GPS heights of the GPS antenna mounted over the SWATHplus-M sonar head. These heights were extracted from each HYPACK navigation file using the AWK script "doRTK1_by_line_FIX" and smoothed in MATLAB (version 7.20.232 R2006a) using a third order polynomial. The smoothed 1-second heights were averaged to 1-minute heights and formatted for use in CARIS HIPS using the AWK script "DoRTK2" to produce the file "TidesAllCARIS.tid" The contact person for this and all subsequent processing steps below is Brian Andrews. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Brian Andrews
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    Date: Sep-2008 (process 2 of 6)
    Step 2. CONVERT SXR to SXP.
    Each raw SWATHplus-M bathymetric sonar file (sxr) was converted to a SWATHplus processed file (sxp) using SEA SWATHplus Swath Processor (ver. 3.5.19). During the conversion process, sound velocity profiles were used to minimize potential refraction artifacts from fluctuations in the speed of sound within the water column. Various bathymetric filters were applied to eliminate sounding outliers.
    Date: Sep-2008 (process 3 of 6)
    A new CARIS HIPS project (ver. 6.1) was created using the Universal Transverse Mercator (UTM) Zone 19, WGS 84 coordinate system. Each SWATHplus processed file (sxp) was imported to the new CARIS project using the Import/Conversion Wizard. A 5-meter resolution Bathymetric and Statistical Error (BASE) Surface was created from the files for each Julian day. The BASE surface for each day was reviewed for any inconsistencies or data anomalies. Navigation was edited as needed using the navigation editor tool in CARIS. Filters were applied to each line including beam to beam slopes and across track angle. The CARIS refraction editor was used to adjust the speed of sound in some cases to flatten out the depth profiles produced by localized variations in speed of sound through the water column.
    Date: Sep-2015 (process 4 of 6)
    Convert CARIS Tracklines to Shapefile: The tracklines in the CARIS project was converted to an ESRI shapefile during a two-step process. First the CARIS tracklines were converted to a CARIS Map using the export tool within HIPS "HIPS to CARIS Map" Input File: All lines in the HIPS Project. The "Export Track Lines" option was checked Output File: "SurveyName"BathTrks.des Second, using CARIS Conversion Utility (ver. 2.1) The CARIS Map (.des) file was converted to an ESRI shapefile. During the conversion the name of the HIPS line file "Line" and "JD" was carried over to the shapefile. Input File: "SurveyName"BathTrks.des Output File: BelfastBay_SWATHplus_bathymetry_tracklines.shp
    Date: Sep-2015 (process 5 of 6)
    The following attributes were added to the shapefile using the "add field" feature in ArcGIS Pro (v. 2.6): Length_km, SurveyID, VesselID, DeviceID. Length_km field was populating using the "calculate geometry" context menu using UTM 19, WGS84 coordinate system. SurveyID, VesselID, and DeviceID text fields were populated using the "calculate field" context menu.
    Date: 25-Jan-2021 (process 6 of 6)
    Changed the distribution format name from digital data to shapefile to better represent the data. 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)
  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?
    All attributes were checked in a consistent manner.
  2. How accurate are the geographic locations?
    These data were navigated using Real-Time Kinematic Global Positioning System (RTK-GPS) which provides horizontal positional accuracies (x and y) on the decimeter scale. The SWATHplus transducers were mounted on a rigid pole from the bow of the R/V Rafael, approximately 0.5 below waterline. Position data were recorded by Hypack Software (v. 4.3).
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Although this shapefile records every trackline where bathymetry was collected during the two surveys, not all lines were used to produce the final grid (BelfastBay_SwathPlus_Bathymetry_5m.tif).
  5. How consistent are the relationships among the observations, including topology?
    This polyline shapefile records the position of each bathymetric trackline collected during surveys 2006-024-FA and 2008-024-FA.

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 re-distributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset. These data are not to be used for navigation.
  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? This data release includes the shapefile BelfastBay_SWATHplus_bathymetry_tracklines.shp, the browse graphic BelfastBay_SWATHplus_bathymetry_tracklines_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file BelfastBay_SWATHplus_bathymetry_tracklines_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 shapefile format, or GIS software capable of utilizing web mapping or feature services.

Who wrote the metadata?

Last modified: 19-Mar-2024
Metadata author:
Brian Andrews
U.S. Geological Survey, Northeast Region
384 Woods Hole Road
Woods Hole, MA

508-548-8700 ext. 2348 (voice)
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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