2015-330-FA_trkln: Digital Chirp Subbottom Profile Trackline Data Collected During USGS Field Activity Number 2015-330-FA Offshore of Dauphin Island, Alabama, September 2015

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Frequently anticipated questions:

What does this data set describe?

Title:
2015-330-FA_trkln: Digital Chirp Subbottom Profile Trackline Data Collected During USGS Field Activity Number 2015-330-FA Offshore of Dauphin Island, Alabama, September 2015
Abstract:
From September 16 through 23, 2015, the U.S. Geological Survey (USGS) conducted geophysical surveys to investigate the geologic controls on barrier island evolution and sediment transport offshore of Dauphin Island, Alabama. Geophysical data were collected as part of the Alabama Barrier Island Restoration Feasibility Study. This shapefile represents a line dataset of field activity number (FAN) 2015-330-FA chirp tracklines.
Supplemental_Information:
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=2015-330-FA and in the Field Activity Collection System (FACS) and geophysical logs, which are included in the download file, 2015-330-FA_logs.zip (Forde and others, 2022).
  1. How might this data set be cited?
    Forde, Arnell S., 20221018, 2015-330-FA_trkln: Digital Chirp Subbottom Profile Trackline Data Collected During USGS Field Activity Number 2015-330-FA Offshore of Dauphin Island, Alabama, September 2015:.

    This is part of the following larger work.

    Forde, Arnell S., Flocks, James G., and Locker, Stanley D., 20221018, Archive of Chirp Subbottom Profile Data Collected in 2015 From Dauphin Island, Alabama: U.S. Geological Survey data release doi:10.5066/P9YTIG6G, 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: -88.328428
    East_Bounding_Coordinate: -88.040933
    North_Bounding_Coordinate: 30.247492
    South_Bounding_Coordinate: 30.158725
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 16-Sep-2015
    Ending_Date: 23-Sep-2015
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Vector Digital Dataset (Polyline)
  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 (113)
    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 0.0197878895. Longitudes are given to the nearest 0.0227703311. 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?
    2015-330-FA_trkln.shp Attribute Table
    Table containing attribute information associated with the dataset. (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.
    Line
    Trackline name (Source: U.S. Geological Survey) The naming convention used for each subbottom line is as follows: xy_bp_mod, where 'x' is an alphanumeric identifier indicating a specific trackline (for example, JD-262 or JD-265b), 'y' is a number (such as, .001, .002, etc.) representing a new line if recording was prematurely terminated or reran for quality or acquisition problems, and 'env_bp' denotes that the seismic traces were output as an envelope and a bandpass filter was applied.
    Image
    Graphics Interchange Format (GIF) image name (Source: U.S. Geological Survey) This attribute field provides the name of the subbottom profile image (.gif) that is associated with each trackline as a hyperlinked GIF; a folder containing all these .gif files, named "images", is included in 2015-330-FA_gis.zip.
    Entity_and_Attribute_Overview:
    Navigation files are available as ASCII delimited text files in CSV format. The final navigation files are provided in 2015-330-FA_nav.zip (Forde and others, 2022) and represent the reprojected survey shotpoint navigation, 1,000-shot-interval locations, and start of line files. The entity and attribute information provided here describes the tabular data associated with the shapefile, 2015-330-FA_trkln.shp. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the dataset.
    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
  2. Who also contributed to the data set?
    Data collection and processing were performed by Jim Flocks, Stan Locker (former employee), and Arnell Forde of the USGS 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
    St. Petersburg, FL
    USA

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

Why was the data set created?

To aid in the registering of digital chirp seismic reflection data collected during USGS FAN 2015-330-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: 11-Mar-2022 (process 1 of 2)
    Navigation files were extracted from the seismic trace headers using Seismic Unix release 44 software, processed with PROJ.5.1.0 software to generate Universal Transverse Mercator (UTM) coordinates from latitude and longitude coordinates (World Geodetic System of 1984, WGS84), and then saved as ASCII text files in comma-separated values (CSV) format. Person who carried out this activity:
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    aforde@usgs.gov
    Date: 22-Mar-2022 (process 2 of 2)
    The reformatted, text files were imported into Esri ArcMap 10.7 software to produce a geographic representation of the subbottom profile tracklines collected within the survey area. The PointsToLine script (located in the ArcToolbox) was used to create a shapefile (.shp) in which individual chirp shotpoints were connected to form tracklines. Person who carried out this activity:
    Arnell S. Forde
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    aforde@usgs.gov
  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?
  2. How accurate are the geographic locations?
    As the subbottom profile data were acquired, the position of the vessel was continuously determined by an Applanix POS MV Wavemaster II inertial aided navigation system (IANS), which is accurate to within 0.5-2 meters (m). Positions from the POS MV were recorded and written to seismic trace headers every second (s). The approximately 19-m offset between the chirp and GPS antenna has not been accounted for in the comma-delimited American Standard Code for Information Interchange (ASCII) navigation files and trackline map.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    A total of 118 seismic lines were collected during this field activity. Two test lines, 2015-330-FA.001 and 2015-330-FA.002, were collected in Mobile Bay on DOY 258. Lines 2015-330-FA, JD-260, and JD-264.003 were partial lines containing no usable data and line JD-264.010 was corrupted during acquisition; consequently, all of the preceding lines were excluded from this data release.
  5. How consistent are the relationships among the observations, including topology?
    This dataset is 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
Use_Constraints 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
  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?
    • Availability in digital form:
      Data format: 2015-330-FA_gis.zip contains the survey navigation data represented geospatially using a Google Earth keyhole markup language zipped (KMZ), Esri ArcMmap document (MXD), shapefiles, and a folder of processed subbottom profile images (GIF, accessible via hyperlinks included in the MXD). This metadata record describes the trackline locations provided in, 2015-330-FA_trkln.shp, which is one of the three Esri shapefiles included in the geographic information system (GIS) data ZIP file. in format Shapefile, MXD, KMZ, GIF Size: 113.1
      Network links: https://coastal.er.usgs.gov/data-release/doi-P9YTIG6G/data/2015-330-FA_gis.zip
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    This shapefile was created for use with Esri ArcGIS software. It may also be viewed with Esri public domain software Explorer for ArcGIS, GeoMapApp 3.6.14 (http://www.geomapapp.org, 2021), or other GIS software capable of importing the data.

Who wrote the metadata?

Dates:
Last modified: 12-Sep-2022
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/2015-330-FA_trkln.shp.faq.html>
Generated by mp version 2.9.51 on Tue Oct 18 12:13:05 2022