Archive of Chirp Sub-Bottom Profile, Imagery, and Navigational Data Collected in June and July 2014 from Fire Island, New York

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Frequently anticipated questions:

What does this data set describe?

Title:
Archive of Chirp Sub-Bottom Profile, Imagery, and Navigational Data Collected in June and July 2014 from Fire Island, New York
Abstract:
During June 15-23 and July 10-12, 2014, the U.S. Geological Survey (USGS) conducted a nearshore geologic assessment, including bathymetric mapping, along Fire Island, New York (NY). This work was conducted in support of efforts to map the shoreface, characterize stratigraphy, and investigate changes in seafloor elevations near Fire Island, NY to assess the impacts of Hurricane Sandy to the area in October 2012. Geophysical data were collected as part of the Hurricane Sandy Supplemental Project (GS2-2B). The data release associated with this metadata record serves as an archive of high-resolution chirp sub-bottom trace data and navigation files. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y revision 0 format (Barry and others, 1975). Processed sub-bottom profile images, survey trackline map, geographic information system (GIS) data, and formal Federal Geographic Data Committee (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM) are also provided.
Supplemental_Information:
Chirp systems use a signal of continuously varying frequency; the system used during this survey produces high-resolution, shallow-penetration (typically less than 75-milliseconds [ms]) profile images of sub-seafloor stratigraphy. The towfish contains a transducer that transmits and receives acoustic energy and is typically towed 1–2 meters (m) below the sea's surface. As transmitted acoustic energy intersects density boundaries, such as the seafloor or sub-surface sediment layers, energy is reflected toward the transducer, received, and recorded by a PC-based seismic acquisition system. This process is repeated at regular intervals (for example, 0.125 seconds [s]) and returned energy is recorded for a specific duration (for example, 50 ms). In this way, a two-dimensional (2D) image of the shallow geologic structure beneath the towfish is produced.
  1. How might this data set be cited?
    Forde, Arnell S., 20240628, Archive of Chirp Sub-Bottom Profile, Imagery, and Navigational Data Collected in June and July 2014 from Fire Island, New York:.

    This is part of the following larger work.

    Forde, Arnell S., Miselis, Jennifer L., and Buster, Noreen A., 20240628, Chirp Sub-Bottom Profile Geophysical Data Collected in 2014 from Fire Island, New York: U.S. Geological Survey data release doi:10.5066/P13TMXXY, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.2225
    East_Bounding_Coordinate: -72.8594
    North_Bounding_Coordinate: 40.7300
    South_Bounding_Coordinate: 40.6093
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 15-Jun-2014
    Ending_Date: 12-Jul-2014
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: SEG-Y, tabular, and raster digital data
  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 0.0197454907. Longitudes are given to the nearest 0.0259102598. 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 1/298.257223563.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Navigation files (2014-303-FA_nav.zip): Navigation files are available as ASCII delimited text files in comma-separated values file format. The survey's shotpoint navigation file, 2014-303-FA_nav.csv (147,014 data records), represents the reprojected survey shotpoint navigation; 2014-303-FA_1000sht.csv (1408 data records) provides 1,000-shot-interval locations; and 2014-303-FA_sol.csv (106 data records) contains start of line information. The shapefile version of these data is available in 2014-303-FA_gis.zip. For more information about these geospatial files, refer to the 2014-303-FA_geospatial_metadata files included in the data release. The navigation and geospatial files share the same attribute labels and definitions, aside from "FID" and "Shape", which are specific to the .shp files. The detailed attribute descriptions for the navigation files are provided in the data dictionary (DataDictionary_SBP.docx), the metadata are not complete without this file.
    Entity_and_Attribute_Overview:
    Binary data files (2014-303-FA_segy.zip): Seismic trace data are available as binary files in SEG-Y format (106 files). These files have a .sgy extension and range in size from 5.3 to 316.8 megabytes. The SEG-Y rev. 0 format (Barry and others, 1975) data presented here consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which include information specific to line and reel number; a trace data block that follows the reel identification header, with the first 240 bytes of each trace block consisting of the binary trace identification header; and seismic data samples that follow the trace identification header.
    Entity_and_Attribute_Overview:
    Graphic image files (2014-303-FA_seisimag.zip): Printable versions of the processed sub-bottom profiles are available as GIF images (106 files).
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual or agency identified as the originator of the dataset. 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)
    • Arnell S. Forde
  2. Who also contributed to the data set?
    Funding and (or) support for this study was provided by Hurricane Sandy Supplemental Funding, the USGS Coastal and Marine Hazards and Resources Program, and the U.S. Army Corps of Engineers (USACE), who provided the Lighter Amphibious Resupply Cargo (LARC) amphibious vehicle/survey vessel, personnel to pilot the vessel, geophysical and bathymetry equipment to conduct this survey, and personnel to operate the survey equipment. Field activity planning was performed by Cheryl Hapke (former USGS employee), Stan Locker (former USGS employee) and Jennifer Miselis (USGS) in collaboration with Jesse McNinch (former USACE employee) and Heidi Wadman (USACE); data collection conducted by Heidi Wadman (USACE), Jennifer Miselis (USGS), and Jesse McNinch (USACE); and data processing performed by Arnell Forde. This document was improved by scientific/editorial and metadata reviews from Rachel Marcuson and Breanna Williams of the PCMSC and SPCMSC, respectively.
  3. To whom should users address questions about the data?
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    Saint Petersburg, FL
    USA

    (727) 502-8000 (voice)
    aforde@usgs.gov

Why was the data set created?

The purpose of the data release described herein is to archive and disseminate digital chirp sub-bottom profile data and associated files collected during USGS Field Activity Number (FAN) 2014-303-FA. Additional survey and data details are available from the USGS Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/fan_info.php?fan=2014-303-FA.

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: 12-Jul-2014 (process 1 of 3)
    Chirp acquisition - Sub-bottom data were acquired from one survey platform that utilized an EdgeTech 512i portable sub-bottom profiling (SBP) system. The seismic system was towed on the starboard side of the 35-foot research vessel, the USACE LARC, in a catamaran sled so that the transducers were 0.91 m below the water’s surface. The vessel and towing configuration allowed seismic data to be collected in < 0.5 m water depth and up the lower beach face (Locker and others, 2017). In total, 106 lines, equivalent to a total of 225 line-kilometers, were surveyed. The seismic source utilized during 2014-303-FA consisted of an EdgeTech 512i towfish running Chesapeake Technology SonarWiz version 5.05 acquisition software and towed on the starboard and aft of the RTK-GPS antenna (fig. 4, Locker and others (2017)). The data were acquired in SEG-Y format at 10 hertz (Hz), which equates to one ping per 0.10 seconds. The frequency sweep was 0.7-12 kHz, pulse length 20 ms, and recording length was 73.64 ms. Based on survey speeds of 3.5-4.5 knots, the shot spacing was roughly 0.450 m. During acquisition, positions from the antenna were recorded and written to the seismic trace headers in arcseconds every 0.10 s. The binary portion of the seismic data provided in the data release is stored in SEG-Y rev. 0, IEEE 32-bit float [big-endian byte order] format, which is a standard digital format that can be read and manipulated by most seismic processing software packages; the first 3,200 bytes of the file header are in ASCII format instead of Extended Binary Coded Decimal Interchange Code (EBCDIC) format. The SEG-Y formatted envelope trace files have a .sgy extension and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU) (Cohen and Stockwell, 2010). The printable profiles (provided in .gif format) are chirp sub-bottom profile images that were processed using SU software. Survey Field Activity Collection System (FACS) logs and acquisition geometry figure are also provided as supplemental information in the data release's file, 2014-303-FA_logs.zip. Person who carried out this activity:
    Jennifer Miselis
    U.S. Geological Survey
    Research Geologist
    600 4th Street South
    St. Petersburg, FL

    (727) 502-8000 (voice)
    jmiselis@usgs.gov
    Date: 26-Apr-2022 (process 2 of 3)
    Chirp processing and image creation - The EdgeTech 512i system recorded the sub-bottom data in SEG-Y rev. 0 format. Enveloped SEG-Y trace data were processed with custom scripts and SU Release 44 (Cohen and Stockwell, 2010) software to produce gained Graphics Interchange Format (GIF) images of the sub-bottom profiles included in the data release. A representative chirp data processing sequence consisted of (1) removing raw [vessel] navigation data for each shot and converting the SEG-Y file to SU format, (2) applying automatic gain control, (3) trimming the trace data TWT to 30 ms (no observable features, aside from multiples, were encountered below that point in the profiles), (4) generating a PostScript image of the traces, and (5) converting the PostScript image to a GIF image. The sub-bottom profile images have tic marks every 200 shots, with labels, larger tic marks, and dashed grid lines every 1000 shots. Person who carried out this activity:
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL

    (727) 502-8000 (voice)
    aforde@usgs.gov
    Data sources used in this process:
    • *.sgy
    Data sources produced in this process:
    • *.gif
    Date: 26-Apr-2022 (process 3 of 3)
    Navigation acquisition and processing - A Real-Time Kinematic Global Positioning System (RTK-GPS) utilizing a base/rover setup was used for positioning onboard the USACE LARC. Real-time positions from the RTK-GPS were recorded and written to the seismic trace headers from the antenna to the topside unit of the chirp system every 0.10 seconds, with unique navigation fixes being recorded every second. During sub-bottom processing, location data were extracted from the SEG-Y headers of the processed chirp profiles, using bespoke scripts and SU (Cohen and Stockwell, 2010) software and output as ASCII text files; PROJ.5.1.0 (https://proj.org/) software was used to project WGS84 latitude and longitude coordinates to Universal Transverse Mercator (UTM) northings and eastings (WGS84, Zone 18 North [N], meters). Navigation files for each sub-bottom line, saved by line number, were concatenated into comma-separated values (.csv) files so they could be represented geospatially in GIS software. The final output files are as follows: (1) 2014-303-FA_nav.csv contains unique shotpoint positions (along each line) for the entire survey – roughly every 10 shots, (2) 2014-303-FA_1000sht.csv includes the 1,000-shot-interval locations that were generated to correlate shot locations along the tracklines with evenly spaced 1,000-shot index markers along the top of the printable profile images, and (3) 2014-303-FA_sol.csv has the start-of-line locations for each trackline. The concatenated, comma-delimited text files were later imported into ArcGIS Pro and saved as either a point or polyline file (in Esri's shapefile format, .shp) for subsequent use in GIS software packages. For more information about these geospatial files, refer to the 2014-303-FA_geospatial_metadata files included in this data release. Person who carried out this activity:
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL

    (727) 502-8000 (voice)
    aforde@usgs.gov
    Data sources used in this process:
    • *.txt
    Data sources produced in this process:
    • 2014-303-FA_nav.csv
    • 2014-303-FA_1000sht.csv
    • 2014-303-FA_sol.csv
  3. What similar or related data should the user be aware of?
    Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics v. 40, no. 2.

    Online Links:

    Other_Citation_Details: pages 344-352
    Cohen, J.K., and Stockwell, J.W., Jr., 2010, Seismic Un*x Release No. 44: An open source software package for seismic research and processing: Center for Wave Phenomena, Colorado School of Mines, Golden, Colorado.

    Online Links:

    Locker, S.D., Miselis, J.L., Buster, N.A., Hapke, C.J., Wadman, H.M., McNinch, J.E., Forde, A.S., and Stalk, C.A., 2017, Nearshore sediment thickness, Fire Island, New York: U.S. Geological Survey Open-File Report 2017–1024, U.S. Geological Survey, Reston, Virginia.

    Online Links:

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

  1. How well have the observations been checked?
    The validity or accuracy of marine sub-bottom profiles is highly qualitative and dependent on equipment and operating condition variables.
  2. How accurate are the geographic locations?
    As the sub-bottom profile data were acquired, the position of the vessel was continuously determined by a Real-Time Kinematic Global Positioning System (RTK-GPS) utilizing a base/rover setup, which is accurate to within 2 centimeters. To ensure consistent spacing between survey lines acquired aboard the USACE's LARC, pre-determined trackline locations were imported into HYPACK 2014 navigation software and followed during seismic data collection. During acquisition, positions from the RTK-GPS were recorded and written to the seismic trace headers in arcseconds every 0.10 s and were subsequently converted to decimal degrees latitude and longitude coordinates (World Geodetic System of 1984, WGS84, realization G1150). The approximate 1-m offset between the chirp shot position and the vessel's RTK-GPS antenna were not accounted for during acquisition, nor have the American Standard Code for Information Interchange (ASCII) navigation files and trackline map been corrected to reflect the offset.
  3. How accurate are the heights or depths?
    These data are not to be used for bathymetry or navigation. Two-way travel times (TWT) shown on the printable profile images are relative to the chirp towfish position (below the sea surface), not to the sea surface.
  4. Where are the gaps in the data? What is missing?
    A total of 106 seismic lines were collected during this field activity. More detail on acquisition conditions is available in the data release file, 2014-303-FA_logs.zip.
  5. How consistent are the relationships among the observations, including topology?
    These datasets are from one field activity with consistent instrument calibrations. Seismic data were collected during two surveys, which occurred on (Leg 1) June 15-23 and (Leg 2) July 10-12, 2014.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None. These data are held in the public domain.
Use_Constraints Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of the data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    SPCMSC Data Management Group
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    gs-g-spcmsc_data_inquiries@usgs.gov
  2. What's the catalog number I need to order this data set? 2014-303-FA_nav.csv, 2014-303-FA_1000sht.csv, 2014-303-FA_sol.csv, *.sgy, *.gif, DataDictionary_SBP.docx
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized seismic processing software, such as public domain software Seismic Unix (https://github.com/JohnWStockwellJr/SeisUnix).

Who wrote the metadata?

Dates:
Last modified: 28-Jun-2024
Metadata author:
SPCMSC Data Management Group
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8000 (voice)
gs-g-spcmsc_data_inquiries@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/2014-303-FA_metadata.faq.html>
Generated by mp version 2.9.51 on Fri Jun 28 12:11:30 2024