Multibeam Mapping of Selected Areas of the Outer Continental Shelf, Northwestern Gulf of Mexico

Frequently-anticipated questions:

• What does this data set describe?
  1. How should 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?

Title:

Multibeam Mapping of Selected Areas of the Outer Continental Shelf, Northwestern Gulf of Mexico

Abstract:

XYZ ASCII format data generated from the 1997 and 2002 multibeam sonar surveys, field activities A-1-97-GM and O-1-02-GM, of selected areas of the outer continental shelf, Northwestern Gulf of Mexico. The data include high-resolution bathymetry and calibrated acoustic backscatter. The specific areas include, East and West Flower Garden Banks, Stetson Bank, Alderdice Bank, Bright Bank, Rankin Banks, Geyer Bank, Jakkula Bank, McGrail Bank, Bouma Bank, MacNeil Bank, and Sonnier Bank.

Supplemental_Information:

Information about USGS Coastal and Marine Geology field activity A-1-97-GM are online at <http://walrus.wr.usgs.gov/infobank/a/a197gm/html/a-1-97-gm.meta.html> Information about USGS Coastal and Marine Geology field activity O-1-02-GM are online at <http://walrus.wr.usgs.gov/infobank/o/o102gm/html/o-1-02-gm.meta.html> >

1. How should this data set be cited?

   United States Geological Survey, Coastal and Marine Geology (CMG), Chief, 2002, Multibeam Mapping of Selected Areas of the Outer Continental Shelf, Northwestern Gulf of Mexico.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -94.514

   East_Bounding_Coordinate: -91.486

   North_Bounding_Coordinate: 28.505

   South_Bounding_Coordinate: 27.491

3. What does it look like?

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

   Beginning_Date: 12-Dec-1997

   Ending_Date: 28-Jun-2002

   Currentness_Reference: ground condition

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

   Geospatial_Data_Presentation_Form: XYZ ASCII

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. It contains the following vector data types (SDTS terminology):

      • Point

   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 0.00004 (0.00005 for East and West Flower Garden Banks and Stetson Bank). Longitudes are given to the nearest 0.00004 (0.00005 for East and West Flower Garden Banks and Stetson Bank). Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.00 meters.
      The flattening of the ellipsoid used is 1/0.003352811.
      

      Vertical_Coordinate_System_Definition:

      Depth_System_Definition:

      Depth_Datum_Name: Mean lower low water

      Depth_Resolution: 0.5% of the water depth

      Depth_Distance_Units: meters

      Depth_Encoding_Method: Implicit coordinate

7. How does the data set describe geographic features?

   Entity_and_Attribute_Overview:

   Sample of bathymetry XYZ ASCII file

   Longitude, Latitude, Elevation
   -86.57406,30.06655,-48.497
   -86.57399,30.06655,-48.473
   -86.57391,30.06655,-48.418
   -86.57383,30.06655,-48.408
   -86.57375,30.06655,-48.411
   -86.57368,30.06655,-48.415
   -86.57430,30.06648,-48.738
   -86.57422,30.06648,-48.728
   -86.57414,30.06648,-48.678
   

   Sample of Backscatter XYZ ASCII file

    Longitude, Latitude, DN Value
   -86.57421,30.06640,207.696
   -86.57413,30.06640,206.398
   -86.57405,30.06640,203.770
   -86.57398,30.06640,201.170
   -86.57390,30.06640,201.098
   -86.57382,30.06640,202.064
   -86.57374,30.06640,202.693
   -86.57367,30.06640,202.720
   -86.57444,30.06632,201.992
   

   Entity_and_Attribute_Detail_Citation: none

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • United States Geological Survey (USGS),

2. Who also contributed to the data set?

3. To whom should users address questions about the data?

   Peter Dartnell
   United States Geological Survey (USGS)
   Physical Scientist
   USGS, 400 Natural Bridges Drive
   Santa Cruz, CA 95060
   USA
   

   831-460-7415(voice)
   831-427-4748(FAX)
   pdartnell@usgs.gov
   

These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) or other software to display bathymetry and backscatter data of selected areas of the outer continental shelf, Northwestern Gulf of Mexico.

1. From what previous works were the data drawn?

2. How were the data generated, processed, and modified?

   Date: 28-Jun-2002 (process 1 of 1)

   The bathymetry and backscatter data were collected along a continuous swath perpendicular to the direction of the ship using a Kongsberg Simrad EM1000 multibeam sonar system for the 2002 survey and a Kongsberg Simrad EM300 multibeam sonar system for the 1997 survey. The data were cleaned of bad navigation and depth readings. Backscatter readings were converted from dB (decibels) to DN (digital number) using the convertion, ABSOLUTE VALUE(2DN/dB), where DN: 0-255 and dB: 0 - -127. The data were gridded into a common grid. The gridded data are converted to an XYZ ASCII format file (Longitude, Latitude, Attribute).

   Person who carried out this activity:
   

   Peter Dartnell
   United States Geological Survey (USGS)
   Physical Scientist
   USGS, 400 Natural Bridges Drive
   Santa Cruz, CA 95060
   USA
   

   831-460-7415 (voice)
   831-427-4748 (FAX)
   pdartnell@usgs.gov
   

3. What similar or related data should the user be aware of?

   United States Geological Survey, Coastal and Marine Geology (CMG), 20020917, USGS CMG O-1-02-GM Metadata.

   Online Links:

   • <http://walrus.wr.usgs.gov/infobank/o/o102gm/html/o-1-02-gm.meta.html>

   This is part of the following larger work.

   United States Geological Survey, Coastal and Marine Geology (CMG), 20020917, USGS CMG InfoBank.

   Online Links:

   • <http://walrus.wr.usgs.gov/infobank/>

1. How well have the observations been checked?

   Not determined.

2. How accurate are the geographic locations?

   50 centimeters

3. How accurate are the heights or depths?

   Not applicable

4. Where are the gaps in the data? What is missing?

   Complete

5. How consistent are the relationships among the observations, including topology?

   Point features present.

Are there legal restrictions on access or use of the data?

Access_Constraints: None

Use_Constraints:

Please recognize the U.S. Geological Survey (USGS) as the source of this information. USGS-authored or produced data and information are in the public domain.

1. Who distributes the data set? (Distributor 1 of 1)

   United States Geological Survey (USGS)
   Box 25286
   Denver, CO 80225
   USA
   

   (888)ASK-USGS (voice)
   

2. What's the catalog number I need to order this data set?

   U.S. Geological Survey Open-file Report of02-411

3. What legal disclaimers am I supposed to read?

   These data not intended for navigational purposes.

   Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

   Neither the U.S. Government nor any agency thereof, 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 data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

   Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ASCII
     Network links:	<https://pubs.usgs.gov/of/2002/0411/>

   • Cost to order the data: None

Dates:

Last modified: 21-Aug-2002

Metadata author:

Pete Dartnell
United States Geological Survey (USGS)
Physical Scientist
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA

(650) 329-5460 (voice)
(650) 329-5411 (FAX)
pdartnell@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)