Geophysical Surveys of Bear Lake, Utah-Idaho, September, 2002 - Sidescan-sonar Mosaic

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Geophysical Surveys of Bear Lake, Utah-Idaho, September, 2002 - Sidescan-sonar Mosaic
    Abstract:
    Bear Lake is a tectonic lake that has existed for at least several hundred thousand years. The lake basin is a relatively simple half graben, a spoon-shaped depression tilted toward the main fault on the east side of the lake. The U.S. Geological Survey, in cooperation with researchers from several universities, has been studying the sediments of Bear Lake since 1996. The general purpose of this effort is to reconstruct past limnological conditions and regional climate on a range of timescales, from hundreds of years to hundreds of thousands of years. This research relates to a variety of human concerns, including water usage in the Bear River basin. Past work has included several coring operations, a seismic-reflection survey, sediment-trap deployments, a barge-mounted drilling operation with the GLAD800 drill rig, and a variety of other studies. The objectives of the September, 2002 operations, preliminarily reported here, were (1) to compile a detailed bathymetric map of the lake using swath-mapping techniques, in order to provide baseline data for a variety of applications and studies, and (2) to complete a sidescan-sonar survey of the lake, providing a nearly complete acoustic image of the lake floor. Limited amounts of subbottom acoustic-reflection data (CHIRP) were also collected, along with samples of lake-floor sediments representative of different kinds of backscatter patterns. These surveys followed an earlier subbottom acoustic-reflection survey (1997), using boomer and 3.5 kHz systems (S. M. Colman, unpublished data).

  1. How should this data set be cited?

    U.S. Geological Survey, 2003, Geophysical Surveys of Bear Lake, Utah-Idaho, September, 2002 - Sidescan-sonar Mosaic.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -111.5
    East_Bounding_Coordinate: -111.17
    North_Bounding_Coordinate: 42.2
    South_Bounding_Coordinate: 41.08

  3. What does it look like?

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

    Beginning_Date: 04-Sep-2002
    Ending_Date: 16-Sep-2002
    Currentness_Reference: Publication Date

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

    Geospatial_Data_Presentation_Form: raster 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?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 12
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -111.000000
      Latitude_of_Projection_Origin: +00.000000
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 500000
      Ordinates (y-coordinates) are specified to the nearest 400000
      Planar coordinates are specified in Meters

  7. How does the data set describe geographic features?

    Tiff Image
    Sidescan-sonar image stored in TIFF format (Source: ESRI)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

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

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

Why was the data set created?

These data represent the first sidescan-sonar survey of Bear Lake, Utah-Idaho. This survey covered 100 percent of the lake floor below 5 meter water depth.

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: 16-Sep-2003 (process 1 of 2)
    The sidescan-sonar data were acquired with a 100 kHz Edgetech sidescan-sonar system. All sidescan-sonar data were logged digitally at a sample rate resulting in a 0.18-m pixel size in the across-track direction and approximately 0.14-m in the along-track direction following the methodology outlined in Danforth and others (1991). A median filtering routine (Malinverno and others, 1990) was applied to the sidescan-sonar data to remove speckle noise, resulting in a 0.73-m pixel size. The data for each survey were further processed and digitally mosaicked using PCI Geomatica Software and procedures described in Danforth and others (1991), Danforth (1997), and Paskevich (1992) resulting in an enhanced, geographically correct, sidescan-sonar mosaic with 1 meter/pixel resolution. The composite mosaic was exported as a TIFF image, with an associated ESRI world file.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

    Data sources used in this process:
    • Danforth, W.W., 1997, Xsonar/ShowImage: A complete system for rapid sidescan-sonar processing and display: U.S. Geological Survey Open File Report 97-686, 77 p.
    • Danforth, W.W., O'Brien, T.F., and Schwab, W.C., 1991, USGS Image processing system: near real-time mosaicking ofhigh-resolution sidescan-sonar data Sea Technology, Vol 1, p.54-59.
    • Malinverno, A., Edwards, M, and Ryan, W.B.F, 1990, Processing of SeaMARC swath sonar data: IEEE, Journal of Coean Enginneering, v.15, p. 14-23.
    • Paskevich, V., 1992, Digital mapping of sidescan-sonar data with the Woods Hole Image Processing System software: U.S. Geological Survey Open-File Report 92-536, 87.p

    Date: 16-Sep-2003 (process 2 of 2)
    The TIFF image (sonar.tif) was compressed using LizardTech, MrSID GeoSpatial Encoder 1.3.1. This software compresses the image at a specified ratio; 20:1 by default. An associated .sdw (ESRI world file) file is written with the compressed .sid file. In order to view these data within ArcView, the MrSID Image Support extension must be loaded. Once, the extension is loaded, the .sid image file can be loaded into ArcView as an Image.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@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?

    These data are internally consistent and accurate.

  2. How accurate are the geographic locations?

    WAAS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. All data were recorded using the WAAS (Wide Area Augmentation System) navigation. All WAAS data are referenced to WGS84 datum. Slant-range distance was assumed to be negligable; the tow-fish was flown at a static height adjacent to the boat.

  3. How accurate are the heights or depths?

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

    These data are complete.

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

    These data are logically consistent; they were acquired with an Edgetech DF-1000 sidescan-sonar system, and processed following an identical procedure.

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 USGS asks to be referenced in any use of these data.

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

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

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

    bear.sid

  3. What legal disclaimers am I supposed to read?

    Altough this data set and its lineage have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or it's related materials. The act of distribution shall not constitute any such warranty, and no resposibility is assumed by the USGS in the use of these data or related items. Users must assume resposibility for the proper use of this data. This data should not be used at resolutions for which it is not intended. This data has no been reviewed for conformity with U.S. Geological Survey editorial standards, or the North American Strigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 19-Jan-2002
Last Reviewed: 2002

Metadata author:
Jane F. Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543
USA

508-457-2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.7.17 on Wed Jul 02 14:24:35 2003