Archive of Digital Chirp Subbottom Profile Data Collected During USGS Cruise 11BIM01 Offshore of the Chandeleur Islands, Louisiana, June 2011

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Forde, Arnell S., Dadisman, Shawn V., Miselis, Jennifer L., Flocks, James G., and Wiese, Dana S., 2013, Archive of Digital Chirp Subbottom Profile Data Collected During USGS Cruise 11BIM01 Offshore of the Chandeleur Islands, Louisiana, June 2011: U.S. Geological Survey Data Series 772, U.S. Geological Survey, St. Petersburg, FL.

   Online Links:

   • http://pubs.usgs.gov/ds/772/
   • http://cmgds.marine.usgs.gov/data/11BIM01/
   • http://pubs.usgs.gov/ds/772/software/arc/

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.920242
   East_Bounding_Coordinate: -88.788672
   North_Bounding_Coordinate: 30.101264
   South_Bounding_Coordinate: 29.871811
   

3. What does it look like?

   http://pubs.usgs.gov/ds/772/maps/11bim01_location.jpg (JPEG)

   Location map (fig. 1) of all digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:157,950.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area1.jpg (JPEG)

   Detailed trackline map (fig.3) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:27,950.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area2.jpg (JPEG)

   Detailed trackline map (fig.4) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:24,000.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area3.jpg (JPEG)

   Detailed trackline map (fig.5) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:30,000.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area4.jpg (JPEG)

   Detailed trackline map (fig.6) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:30,000.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area5.jpg (JPEG)

   Detailed trackline map (fig.7) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:29,500.

   http://pubs.usgs.gov/ds/772/maps/11bim01_area6.jpg (JPEG)

   Detailed trackline map (fig.8) of digital chirp subbottom data collected during USGS Field Activity 11BIM01. This map was created at a scale of 1:79,500.

   http://pubs.usgs.gov/ds/772/profiles/printable/ (GIF)

   Directory containing printable images of all subbottom profiles.

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 03-Jun-2011

   Ending_Date: 13-Jun-2011

   Currentness_Reference:

   Data collection interval

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: Archive for Subbottom Profile Data
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      

      Indirect_Spatial_Reference:

      Horizontal X and Y locations (latitude and longitude and Zone 16 UTM coordinates) for each shot are provided as ASCII text files, along with the date and time (UTC) the shot was recorded.

      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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS84.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.25722210100002.
      
7. How does the data set describe geographic features?

   11bim01.txt, s11bim01.txt, and 11bim01_s.txt

   Shotpoint navigation files (Source: SEG Y headers (http://www.seg.org/publications/tech-stand).)

   FID*

   Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.

   Shape*

   Feature geometry. (Source: ESRI) Coordinates defining the features.

   UTMX

   UTM-X coordinate (Zone 16) (Source: Universal Transverse Mercator Geographic Coordinate System)

   Range of values
   Minimum:	315130
   Maximum:	326898
   Units:	meters

   UTMY

   UTM-Y coordinate (Zone 16) (Source: Universal Transverse Mercator Geographic Coordinate System)

   Range of values
   Minimum:	3308709
   Maximum:	3331466
   Units:	meters

   Line

   Trackline number (Source: U.S. Geological Survey) The naming convention used for each subbottom line is as follows: yye##a, where 'yy' are the last two digits of the year in which the data were collected, 'e' is a 1-letter abbreviation for the equipment type (for example, c for Chirp), '##' is a 2-digit number representing a specific track, and 'a' is a letter representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems.

   Shot

   Shotpoint number (Source: U.S. Geological Survey)

   Range of values
   Minimum:	1
   Maximum:	11354

   Lon

   Longitude (decimal degrees) (Source: World Geodetic System 1984 Geographic Coordinate System)

   Range of values
   Minimum:	-88.917917
   Maximum:	-88.793833
   Units:	decimal degrees

   Lat

   Latitude (decimal degrees) (Source: World Geodetic System 1984 Geographic Coordinate System)

   Range of values
   Minimum:	29.896167
   Maximum:	30.101153
   Units:	decimal degrees

   YEAR

   Year (Source: U.S. Geological Survey)

   Range of values
   Minimum:	2011
   Maximum:	2011

   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

   Entity_and_Attribute_Overview:

   Binary data file: Trace data are available as binary files in SEG Y format. These files have a .sgy extension and range in size from 6.1 to 200.3 MB. These data can be found by going to http://pubs.usgs.gov/772/647/segy.

   Entity_and_Attribute_Overview:

   Graphic image file: Printable versions of the subbottom profiles are available as GIF images, links to these images can be found on the Profiles page or by going to http://pubs.usgs.gov/ds/772/profiles/printable/.

   Entity_and_Attribute_Overview:

   Navigation file: Navigation files are available as ASCII text files. Provided are raw (unprocessed) shotpoint navigation files (11c**.txt), processed shotpoint navigation (11bim01.txt), processed 1,000-shot-interval location (s11bim01.txt), and a start of line file (11bim01_s.txt). Fields/Attributes [FID, Shape] marked above with an asterisk (*) were created by ESRI ArcGIS and are used exclusively by the shapefiles created from the three aforementioned .txt files; these fields are not included in the original navigation files. All remaining attributes listed above in the Entity_and_Attribute_Information: section that do not have an accompanying asterisk are found in 11bim01.txt, s11bim01.txt, and11bim01_s.txt. Raw and processed navigation data files can be found by going to http://pubs.usgs.gov/ds/772/nav/.

   Entity_and_Attribute_Overview:

   GIS file: The GIS project used to create the trackline maps is provided as a .zip file composed of ESRI map documents, shapefiles, and metadata.

   Entity_and_Attribute_Detail_Citation: Information is derived from SEG Y headers.
   

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
   • Shawn V. Dadisman
   • Jennifer L. Miselis
   • James G. Flocks
   • Dana S. Wiese
2. Who also contributed to the data set?

   Funding and (or) support for this study was provided by the USGS Coastal and Marine Geology Program. We thank R/V Survey Cat captain Nancy DeWitt (SPCMSC) for her assistance in data collection and Will Pfeiffer and Noreen Buster for their assistance with swath data processing. This document was improved by the reviews Paul Knorr and Kyle Kelso of the USGS - St. Petersburg, FL.Disc Image Credit: Schmaltz, Jeff, MODIS Rapid Response Team at the NASA Goddard Space Flight Center, 2004, UnitedStates.A2004106.1855.500m.jpg. Also available on-line at http://eoimages.gsfc.nasa.gov/ve/6886/UnitedStates.A2004106.1855.500m.jpg

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) 803-8747 ext. 3111 (voice)

   aforde@usgs.gov

Why was the data set created?

To archive all digital chirp subbottom profile data and associated files collected during cruise 11BIM01.

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: 2012 (process 1 of 6)

   Chirp processing:The SEG Y data were processed with Seismic Unix to produce gained GIF images of the subbottom profiles included in this report. A representative Chirp data processing sequence consisted of (1) stripping off navigation data for each shot and converting to SU format, (2) applying automatic gain control, (3) generating a PostScript image of the traces, and (4) converting the PostScript image to a GIF image. For additional SU processing and script details, please refer to http://pubs.usgs.gov/ds/772/software/su/readme.txt. Person who carried out this activity:
   

   Arnell S. Forde

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   (727) 803-8747, ext. 3111 (voice)

   aforde@usgs.gov

   Data sources used in this process:

   • SEG Y

   Data sources produced in this process:

   • printable/SEG Y.gif

   Date: 2012 (process 2 of 6)

   Navigation processing: Shotpoint navigation, start of line, and 1,000-shot-interval location files were extracted using Seismic Unix software and output as ASCII text files; they were then processed with PROJ.4.7.0 (http://trac.osgeo.org/proj/) to generate UTM coordinates (WGS84, Zone 16, meters) from latitude and longitude coordinates. Text files for each seismic line were concatenated into two comma-delimited text files (for use with ESRI software), one containing unique shotpoint positions (11bim01.txt) and another containing the 1,000-shot-interval locations (s11bim01.txt); both can be viewed within the nav folder. Person who carried out this activity:
   

   Arnell S. Forde

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   (727) 803-8747, ext. 3111 (voice)

   aforde@usgs.gov

   Data sources used in this process:

   • 11c**.txt

   Data sources produced in this process:

   • 11bim01.txt
   • s11bim01.txt
   • 11bim01_s.txt

   Date: 2012 (process 3 of 6)

   All concatenated, comma-delimited text files were imported into ArcGIS and saved as either a point or polyline file in the ESRI shapefile format.Trackline map creation: The trackline maps was created using ESRI ArcGIS 10 software. The processed navigation file, 11bim01.txt, was imported into ArcMap 10 and processed using the Points to Lines ArcScript (D. Rathert, http://arcscripts.esri.com/details.asp?dbid=12702) to create a line shapefile of the cruise tracklines (11bim01_trkln). The 1,000-shot-interval file s11bim01.txt and the start of line file 11bim01_s.txt were imported into ArcMap as point shapefiles 11bim01_shots and 11bim01_sol. Please refer to the shapefile metadata included in the ArcGIS map document located under the Software section of this archive for additional details. All maps was exported to Adobe Illustrator v. 14 for further editing then later converted into JPEG format by Adobe Dreamweaver v. 10 Build 4117. The maps are unprojected (geographic coordinates, WGS84). The USGS is the originator of all layers used. Please see the ArcGIS readme file for detailed information about the GIS files used in this report. Please see the ArcGIS readme file for detailed information about the GIS files used in this report. Person who carried out this activity:
   

   Arnell S. Forde

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   (727) 803-8747, ext. 3111 (voice)

   aforde@usgs.gov

   Data sources used in this process:

   • 11bim01.txt
   • s11bim01.txt
   • 11bim01_s.txt

   Data sources produced in this process:

   • 11bim01_shots.shp
   • 11bim01_trkln.shp
   • 11bim01_sol.shp

   Date: 2012 (process 4 of 6)

   Data Series preparation: In addition to the process steps described above, the following steps were taken to produce this Data Series report: the handwritten cruise logs were scanned and saved as a PDF file, digital logs were created by A. Forde using the cruise logs and personal accounts of the crew members and saved as PDF files, and an HTML-based format was used to present the various parts of this archive. Person who carried out this activity:
   

   Arnell S. Forde

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   (727) 803-8747, ext. 3111 (voice)

   aforde@usgs.gov

   Date: 24-Jan-2017 (process 5 of 6)

   Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Alan O. Allwardt

   Contractor -- Information Specialist

   2885 Mission Street

   Santa Cruz, CA
   

   831-460-7551 (voice)

   831-427-4748 (FAX)

   aallwardt@usgs.gov

   Date: 13-Oct-2020 (process 6 of 6)

   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?
   Cohen, J.K., and Stockwell, J.W., Jr., CWP/SU, 2010, Seismic Unix Release 41: A free package for seismic research and processing, Center for Wave Phenomena, Colorado School of Mines.

   Online Links:

   • http://www.cwp.mines.edu/cwpcodes/index.html

   Zihlman, F.N., USGS, 1992, DUMPSEGY V1.0: A program to examine the contents of SEG Y disk-image seismic data: U.S. Geological Survey Open-File Report 92-590.

   Online Links:

   • http://pubs.er.usgs.gov/usgspubs/ofr/ofr92590

   Other_Citation_Details: 28 pages
   

   Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics v. 40, no. 2.

   Online Links:

   • http://www.seg.org/publications/tech-stand/

   Other_Citation_Details: pages 344-352
   

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 depends on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show any major anomalies.
2. How accurate are the geographic locations?
   As the subbottom data were acquired, the position of the vessel was continuously determined by a CodaOctopus F190 DGPS and subsequently sent to Hypack 2010 navigation software to ensure a consistent grid spacing during data collection. Positions were recorded and written to the trace headers in latitude and longitude coordinates about every 1 s using navigation from the CodaOctopus F190 receiver with OmniSTAR High Performance (HP) correction (accurate to within 20 cm). The approximately 2-m offset between the Chirp shot and ship's GPS was not accounted for during acquisition nor have the ASCII navigation files and trackline maps been corrected to reflect the offset.
3. How accurate are the heights or depths?
   These data are not to be used for bathymetry. Two-way travel (TWT) times shown on the printable profile images are relative to the Chirp towfish position, not to the sea surface. Any elevation change of the towfish is recorded in the logbooks and identifiable on the subbottom profiles by steep, abrupt shifts in the seafloor return.
4. Where are the gaps in the data? What is missing?
   These data are collected along tracklines (2-D) and are therefore inherently incomplete. Geologic details between lines must be inferred. No data were collected for lines 11c49, 11c74, 11c75, 11c76, and 11c131. While attempting to collect data for line 11c49, it was determined that the chirp cable was malfunctioning. A temporary splint was placed on the cable for line 11c50; however, a generator failure also occurred at this time resulting in the system being restarted for the subsequent line. Line 11c51 lost navigation data between shots 3032-3510, which was probably due to the loss of power mentioned previously. No navigation fixes were recoreded for line 11c128_b from shots 3281-3523, this too was most likely caused by a temporary loss of power (please see the operation log for additional information).
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. These data are held in the public domain.
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 Forde

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 803-8747, ext. 3111 (voice)

   aforde@usgs.gov

   Contact_Instructions:

   All of this report is available online. The SEG Y files are downloadable from the Coastal and Marine Geoscience Data System (http://cmgds.marine.usgs.gov).

2. What's the catalog number I need to order this data set? U.S. Geological Survey Data Series 772
3. What legal disclaimers am I supposed to read?

   This DVD publication was prepared by an agency of the United States Government. Although these data have been 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:	The SEG Y rev. 0 format (Barry and others, 1975) 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. in format SEG Y rev. 0 Size: 29410
     Network links:	http://cmgds.marine.usgs.gov/data/11BIM01/
     Media you can order:	DVD (format ISO 9660) Note: Unix, Linux, DOS, Macintosh

     Data format:

     The GIS project used to create the trackline maps is composed of map documents, shapefiles, and metadata. Map documents were created with ESRI ArcGIS 10 software. The shapefiles provided may also be viewed using other versions of ESRI desktop software including their free software or ArcGIS Explorer (http://www.esri.com/software/arcgis/explorer/index.html). in format map document, shapefile, metadata Size: 149

     Network links:

     http://pubs.usgs.gov/ds/772/software/arc/arc.zip

   • Cost to order the data: None, if obtained online; otherwise, prices vary.

   • Special instructions:

     Publications are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS, e-mail: infoservices@usgs.gov).

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 (http://www.cwp.mines.edu/cwpcodes/index.html).

Who wrote the metadata?

Dates:

Last modified: 13-Oct-2020

Metadata author:

Arnell Forde

U.S. Geological Survey

Geologist

600 4th Street South

St. Petersburg, FL

USA

(727) 803-8747, ext. 3111 (voice)

aforde@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)