Archive of Chirp Subbottom Profile, Imagery, and Geospatial Data Collected in 2019 from Rockaway Peninsula, New York

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Frequently anticipated questions:

What does this data set describe?

Title:
Archive of Chirp Subbottom Profile, Imagery, and Geospatial Data Collected in 2019 from Rockaway Peninsula, New York
Abstract:
From September 27 through October 5, 2019, researchers from the U.S. Geological Survey (USGS) conducted a geophysical survey to investigate shoreface morphology and geology near the Rockaway Peninsula, New York. The Coastal Sediment Availability and Flux project objectives include understanding the morphologic evolution of the barrier island system on a variety of time scales (months to centuries) and resolving storm-related impacts, post-storm beach response, and recovery. This publication serves as an archive of high-resolution chirp subbottom trace data, survey trackline map, navigation files, geographic information system (GIS) data, and formal Federal Geographic Data Committee (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Processed subbottom profile images are also provided. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y revision 0 format (Barry and others, 1975). In addition to this data release, the SEG-Y files can be downloaded from the USGS Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov. Bathymetry and backscatter data were also collected during this survey and are available in Stalk and others (2020).
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) vertical image of the shallow geologic structure beneath the towfish is produced.
  1. How might this data set be cited?
    Forde, Arnell S., Wei, Emily A., and DeWitt, Nancy T., 20210525, Archive of Chirp Subbottom Profile, Imagery, and Geospatial Data Collected in 2019 from Rockaway Peninsula, New York:.

    This is part of the following larger work.

    Forde, Arnell S., Wei, Emily A., DeWitt, Nancy T., and Miselis, Jennifer L., 20210525, Archive of Chirp Subbottom Profile Data Collected in 2019 From Rockaway Peninsula, New York: U.S. Geological Survey data release doi:10.5066/P9ZO8QKJ, 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: -73.9392
    East_Bounding_Coordinate: -73.7509
    North_Bounding_Coordinate: 40.5906
    South_Bounding_Coordinate: 40.5296
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 27-Sep-2019
    Ending_Date: 05-Oct-2019
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: SEG-Y, tabular, vector, and raster 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 0.0197459685. Longitudes are given to the nearest 0.0258684611. 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?
    2019-333-FA_slednav.csv (415639 data records), 2019-333-FA_1000sht.csv (381 data records), 2019-333-FA_sol.csv (73 data records).
    These files, which are located in 2019-333-FA_nav.zip, represent the September–October 2019 subbottom navigation data. The attributes described below are for the survey's shotpoint navigation file, 2019-333-FA_slednav.csv. For detailed information specific to the ArcGIS data, please see the associated shapefile metadata. (Source: U.S. Geological Survey)
    UTMX
    UTM-X coordinate (Zone 18) (Source: Universal Transverse Mercator Coordinate System)
    Range of values
    Minimum:589831.239
    Maximum:605698.059
    Units:meters
    UTMY
    UTM-Y coordinate (Zone 18) (Source: Universal Transverse Mercator Coordinate System)
    Range of values
    Minimum:4487092.777
    Maximum:4494055.547
    Units:meters
    Line
    Trackline name (Source: U.S. Geological Survey) The naming convention used for each subbottom line is as follows: exy_bp_mod, where 'e' means the seismic traces were output as an envelope, 'x' is an 8-digit number indicating a specific trackline (for example, 0002_1609), 'y' is a letter (such as, a or b) representing a new line if recording was prematurely terminated or reran for quality or acquisition problems, and '_bp_mod' denotes that the seismic data were bandpass filtered and modified to use post-processed GPS coordinates for navigation. Line numbers were automatically assigned by the chirp topside unit during data acquisition and are composed of a 4-digit Hypack trackline number and a 4-digit timestamp corresponding to the line's start time. There are four transit lines (etransit_to_13_bp_mod, etransit_to_beach_bp_mod, eTransitlogJD278_bp_mod, and e20190902155831_bp_mod) whose file names were manually entered and therefore do not follow the aforementioned convention.
    Shot
    Shotpoint number (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:37812
    Lon
    Longitude (decimal degrees) (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-73.939211
    Maximum:-73.750922
    Units:decimal degrees
    Lat
    Latitude (decimal degrees) (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:40.529583
    Maximum:40.59055
    Units:decimal degrees
    YEAR
    Year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:2019
    Maximum:2019
    DOY:HR:MIN:SEC
    Day of year:hour:minute:second (Source: U.S. Geological Survey) Day of year, hour, minute and second of data acquisition, in Coordinated Universal Time (UTC).
    Entity_and_Attribute_Overview:
    Navigation file: Navigation files are available as ASCII delimited text files in comma-separated values (CSV) file format. The final navigation files are provided in 2019-333-FA_nav.zip (Forde and others, 2021) and represent the reprojected survey shotpoint navigation, 1,000-shot-interval locations, and start of line files.
    Entity_and_Attribute_Overview:
    Binary data file: Seismic trace data are available as binary files in SEG-Y format (73 files). These files have a .sgy extension and range in size from 62.1 to 576.6 MB. These data are included in the download file, 2019-333-FA_segy.zip, and can also be found by going to the USGS CMGDS at, https://cmgds.marine.usgs.gov. 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 file: Printable versions of the processed subbottom profiles are available as GIF images (73 files) and are included in the download file, 2019-333-FA_seisimag.zip.
    Entity_and_Attribute_Overview:
    GIS file: The GIS data associated with this survey are provided as a compressed zip file, 2019-333-FA_gis.zip, which is composed of an Esri map document, shapefiles, individual shapefile metadata, a Google Earth KMZ file, a folder of processed subbottom profile images, and a readme file. The shapefiles provided may also be viewed using other versions of Esri desktop software including their free software, Explorer for ArcGIS, which is available at https://www.esri.com/en-us/arcgis/products/explorer-for-arcgis.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/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
    • Emily A. Wei
    • Nancy T. DeWitt
  2. Who also contributed to the data set?
    Funding and (or) support for this study were provided by the USGS Coastal and Marine Hazards and Resources Program. The authors thank Andrew Farmer of the USGS for his assistance in data collection and piloting the R/V Sallenger. This document was improved by scientific/editorial and metadata reviews from VeeAnn Cross of the Woods Hole Coastal and Marine Science Center and Breanna Williams of the St. Petersburg Coastal and Marine Science Center.
  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 this data release is to facilitate the archival of digital chirp subbottom profile data and associated files collected during USGS Field Activity Number 2019-333-FA. Additional survey and data details are available from the USGS CMGDS at, https://cmgds.marine.usgs.gov/fan_info.php?fan=2019-333-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: 05-Oct-2019 (process 1 of 5)
    Chirp acquisition - USGS scientists created a purpose-built, towed sled system to mount the 512i chirp subbottom profiler (just below the water's surface) and enable launching and recovery from beach environments. The seismic sled was also configured to help ensure the quality of data collected in exceedingly shallow water depths, such as those observed near the shoreline, over shallow nearshore bars, and within the surf zone. Subbottom data were acquired from one survey platform, the seismic sled, which was towed by the 26-foot research vessel, the R/V Sallenger. 74 lines, equivalent to a total of 210.17 line-kilometers, were surveyed. The seismic source utilized during 2019-333-FA consisted of an EdgeTech SB-512i towfish running DISCOVER version 4.09 acquisition software and towed on the port side of the R/V Sallenger, approximately 14 m behind the global positioning system (GPS) reference point. The data were acquired at 5 hertz (Hz), which equates to a 0.2 s sample interval, using a frequency sweep of 0.7-12 kilohertz (kHz), and recording length was approximately 172.5 ms. Based on survey speeds of 3.5-4.5 knots, the shot spacing was approximately 0.450 m. The binary portion of the seismic data is stored in SEG-Y rev. 0, IBM 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 American Standard Code for Information Interchange (ASCII) format instead of Extended Binary Coded Decimal Interchange Code (EBCDIC) format. The SEG-Y formatted 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 are chirp subbottom profile images that were processed using SU software. Survey Field Activity Collection System (FACS) and geophysical logs are also provided as supplemental information in the download file, 2019-333-FA_logs.zip. Person who carried out this activity:
    Emily A. Wei
    U.S. Geological Survey
    Research Geologist
    600 4th Street South
    St. Petersburg, FL

    (727) 502-8000 (voice)
    ewei@usgs.gov
    Date: 04-Feb-2021 (process 2 of 5)
    Chirp processing - The SEG-Y data were processed with Seismic Unix (Release 44) software to produce gained Graphics Interchange Format (GIF) images of the subbottom profiles included in this data release. Preliminary processing was conducted by E. Wei in October 2019; however, additional issues were observed in the trace data during the QA/QC process that resulted in the subbottom data being reprocessed by A. Forde in February 2021. A representative chirp data processing sequence consisted of (1) applying a 3000-4000-10,000-12,000 bandpass filter to the analytic data to remove noise from the raw data, prior to creating the envelope seismic data file (each line number had an "e" added as a prefix), (2) removing raw [vessel] navigation data for each shot and converting the SEG-Y file to SU format, (3) inserting DGPS, as arcseconds, into the source coordinate headers (corrected files included in this publication have "_bp_mod" appended to the line name), (4) applying automatic gain control, (5) trimming the trace data TWT to 30 ms (no observable features, aside from multiples, were encountered below that point in the profile), (6) generating a PostScript image of the traces, and (7) converting the PostScript image to a GIF image. 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:
    • SEG-Y
    Data sources produced in this process:
    • SEG-Y.gif
    Date: 2019 (process 3 of 5)
    GPS Acquisition - A GPS base station, RIIS, was established near the survey area. RIIS is a USGS installed P/K nail located in the dockage area of the former Riis Landing U.S. Coast Guard Station located just west of the Marine Parkway Bridge on the Rockaway Peninsula. The base station was continually occupied and equipped with a Spectra Precision SP90M GPS receiver recording full-carrier-phase positioning signals (L1/L2) from satellites via Thales Choke-ring antennas, recording at a rate of 0.1 s. Supplementary acquisition and processing information for the navigation data associated with the seismic sled and GPS are included in Rockaway_2019_SBES_metadata.txt (Stalk and others, 2020).
    Date: 04-Feb-2021 (process 4 of 5)
    Navigation acquisition and processing - An Ashtech ProFlex 500 unit with a global navigation satellite system antenna (positioned amidships) was used for positioning onboard the R/V Sallenger. Real-time positions from the ProFlex were recorded and written to the seismic trace headers via a RS232 cable running from the ProFlex receiver to the topside unit of the chirp system every second. During subbottom processing, vessel coordinates previously saved to the seismic headers were replaced with post-processed GPS. Once updated, location data were extracted from the SEG-Y headers of the processed chirp profiles, using Seismic Unix software and output as ASCII text files; PROJ.5.1.0 (https://proj4.org/) software was used to project WGS84 latitude and longitude coordinates to Universal Transverse Mercator (UTM) northings and eastings (WGS84, Zone 18, meters). Navigation files for each subbottom line, saved by line number, were concatenated into comma-delimited text files so they could be represented geospatially using Esri ArcGIS software. The final output files are as follows: (1) 2019-333-FA_slednav.csv contains unique shotpoint positions (along each line) for the entire survey, (2) 2019-333-FA_1000sht.csv includes the 1,000-shot-interval locations that were generated to correlate shot locations on the trackline map with evenly spaced 1,000-shot index markers along the top of the printable profile images, and (3) 2019-333-FA_sol.csv has the start-of-line locations for each trackline. The concatenated, comma-delimited text files were later imported into ArcGIS and saved as either a point or polyline file (in Esri's shapefile format) for use in the map document (.mxd) included in this archive. 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:
    • *_bp_mod.txt
    Data sources produced in this process:
    • 2019-333-FA_slednav.csv
    • 2019-333-FA_1000sht.csv
    • 2019-333-FA_sol.csv
    Date: 18-Feb-2021 (process 5 of 5)
    Trackline map creation - 2019-333-FA_location.mxd and associated shapefiles (.shp) were created with Esri ArcGIS 10.6 software. The survey navigation file, 2019-333-FA_slednav.csv, was imported into ArcMap 10.6.0.8321 and processed using the ArcScript "Points to Lines" to create a polyline shapefile of the cruise tracklines called 2019-333-FA_trkln. The 1,000-shot-interval and start-of-line files, 2019-333-FA_1000sht.csv and 2019-333-FA_sol.csv, were imported into ArcMap and saved as point shapefiles. A non-proprietary version of the location map was created by utilizing the ArcToolbox "Map to KML" tool, which converted each layer included in the .mxd document to keyhole markup language (.kml) format prior to them being compressed and saved as a .kmz file. The ArcGIS and Google Earth geospatial files provided in this publication are unprojected (geographic coordinates, WGS84). For detailed information about the ArcGIS files provided in this data release, please refer to the individual metadata records (*_metadata.txt and *.shp.xml) accompanying each shapefile and the readme file included in 2019-333-FA_gis.zip. 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:
    • 2019-333-FA_slednav.csv
    • 2019-333-FA_1000sht.csv
    • 2019-333-FA_sol.csv
    Data sources produced in this process:
    • 2019-333-FA_trkln.shp
    • 2019-333-FA_shots.shp
    • 2019-333-FA_sol.shp
    • 2019-333-FA.kmz
  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:

    Stalk, C.A., DeWitt, N.T., Wei, E.A., Farmer, A.S., Miselis, J.L., and Fredericks, J.J., 20201112, Coastal Bathymetry and Backscatter Data Collected in September and October 2019 from Rockaway Peninsula, New York: U.S. Geological Survey data release doi:10.5066/P9WNJSFN, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

    Wei, E.A., Miselis, J. L., and Forde, A.S., 20211105, Shoreface and Holocene Sediment Thickness Offshore of Rockaway Peninsula, New York: U.S. Geological Survey Open-File Report 2021-1100, 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 subbottom profiles is highly qualitative and dependent on equipment and operating condition variables. Due to a problem with the acquisition computer's clock, the wrong day of year (DOY) was recorded to the SEG-Y files acquired in the field; however, the correct DOY was recorded to the [proprietary] JSTAR Standard Format (JSF) files (.jsf) that were saved concurrently along with the SEG-Y files. To correct this issue, the .jsf files were converted to SEG-Y format and subsequently used during subbottom processing. During preliminary chirp data processing, visual inspection of the images rendered from the subbottom data showed the presence of an anomaly at approximately 10 ms (two-way travel time [TWT]) on some profiles. This issue was resolved during post-processing and the data were re-checked for quality assurance/quality (QA/QC) control compliance.
  2. How accurate are the geographic locations?
    Both subbottom and bathymetry data were collected aboard a towed seismic sled, which was outfitted with a GPS receiver and single-beam echosounder. A Spectra Precision SP90M GPS receiver was used to collect position information on the sled. Differential positioning was obtained through post-processing the base station (established on USGS benchmark RIIS) data to the rover located on the sled. Manufacture stated accuracy for positioning utilizing a differential GPS (DGPS) is 0.5-2 m. To ensure consistent spacing between survey lines (for example, 5 m in the nearshore and 10 m for offshore lines), a similar GPS set up was established aboard the R/V Sallenger, where pre-determined trackline locations were imported into HYPACK 2018 navigation software and followed during seismic data collection. During acquisition, positions from the Ashtech ProFlex 500 receiver located on the R/V Sallenger were recorded and written to seismic trace headers in arcseconds every 1 second (s) and were subsequently converted to latitude and longitude coordinates (World Geodetic System of 1984, WGS84, realization G1762). The approximate 14-m offset between the chirp shot/sled position and ship's GPS antenna reference point were not accounted for during acquisition. For additional positional accuracy and navigation details specific to the GPS and bathymetry data, please refer to the metadata included in Stalk and others (2020).
  3. How accurate are the heights or depths?
    These data are not to be used for bathymetry. TWT times shown on the printable profile images are relative to the chirp towfish position (just below the sea surface), not to the sea surface.
  4. Where are the gaps in the data? What is missing?
    A total of 74 seismic lines were collected during this field activity. Due to user error, only a portion of line e0021_1955 was recorded in the field so the line was rerun and saved as e0021_1955a. e0021_1955_bp_mod.sgy is a partial file (< 1 megabyte [MB]) containing no usable data; consequently, it is not included in this data release. For the last two subbottom lines collected on DOY 278, an equipment issue resulted in the incorrect DOY (283) being recorded for 4 pings at 19:04:45 of line e0066_1819_bp_mod.sgy and 3 pings at 21:04:51 of e0068_2016b_bp_mod.sgy; this issue was also corrected during post-processing.
  5. How consistent are the relationships among the observations, including topology?
    These datasets are from one field activity with consistent instrument calibrations.

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)
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    aforde@usgs.gov
    Contact_Instructions:
    The SEG-Y files included in this data release are also downloadable from the Coastal and Marine Geoscience Data System at, https://cmgds.marine.usgs.gov.
  2. What's the catalog number I need to order this data set?
  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: 08-Nov-2021
Metadata author:
Arnell S. Forde
U.S. Geological Survey
Geologist
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8000 (voice)
aforde@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/2019-333-FA_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Nov 9 09:57:58 2021