Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPG Images of Sound Velocity Profiles

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:

Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPG Images of Sound Velocity Profiles

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 - JPG Images of Sound Velocity Profiles.

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: Ground Condition

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

   Geospatial_Data_Presentation_Form: JPEG Data

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

      This is a Raster 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 0.000089992. Longitudes are given to the nearest 0.000089992. 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 6378137.0000000.
      The flattening of the ellipsoid used is 1/298.26.
      

7. How does the data set describe geographic features?

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

2. Who also contributed to the data set?

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

   U.S. Geological Survey
   c/o Jane F. Denny
   Geologist, Seafloor Mapping Group
   384 Woods Hole Road
   Woods Hole, MA 012543
   USA
   

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

   Hours_of_Service: Monday-Friday, 8am-5pm, Eastern Standard Time

Sound velocity profiles were collected in order to map the sound velocity profile of the water column. The interferometric sonar systems acquires high-resolution bathymetric measurements in a swath. However, changes in the sound velocity profile with depth will affect the acousit ray path. The acoustic ray path must be accurately modeled in order to calculate accurate depth and position of individual soundings.

1. From what previous works were the data drawn?

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

   Date: 2003 (process 1 of 1)

   Sound Velocity profiles were collected throughout the study area to map the velocity structure of the water column. Changes in the speed of sound throughout the water column will affect the swath bathymetric data; outer beams will experience refraction. The SVP was deployed and sent to the lake floor. Upon retrieval, data were downloaded and placed into a Mircosoft Excel spreadsheet. The individual profiles within the MS Excel spreadsheet were plotted, copied from Excel, pasted as a 'New' file with Adobe Photoshop 6.0, and saved in JPG format. The tabular data were exported from the Excel spreadsheet to a text file. The USGS Mapgen PROJ command was used to convert latitude and longitude values to eastings and northings (UTM Zone 12, WGS84 ellipsoid). This file was imported into ArcView as a table. The table was then converted to a shapefile. The JPG images of the sound velocity profiles were then hotlinked to the sound velocity profile shapefile.

   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?

1. How well have the observations been checked?

   Attribute data are location data. These locations are accurate within 3 meters (recorded WAAS horizontal accuracy).

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. All sample locations are assumed to be accurate to +/- 3 meters.

3. How accurate are the heights or depths?

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

   These data are known to be complete.

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

   These data were all acquired with a Applied Microsystems Sound Velocity Profiler deployed off of the same platform. These data were collected throughout the survey area.

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?

   JPG Images of Grab Samples

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?

Dates:

Last modified: 25-Apr-2003
Last Reviewed: 2003

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)