• Introduction
  
• Methods
  
• Data
  
• Seismic Profiles
• Sidescan-Sonar Mosaic
• Bathymetric Image
• Navigation
• Grab Samples
• Sound Velociy Profiles


• Acknowledgements
  
• Figure Captions

Data
Sound Velocity Profiles

When acquiring bathymetric data, the time of travel of an acoustic wave from the transducer to the seafloor and back (two-way travel time) is measured; depth is not directly measured. In order to convert Figure 8. Diagram showing two-way travel of an acousitc ray, normal to the transdcuer. travel time to depth, the speed of sound in the water column must be measured (Fig. 8). The depth measurements, or soundings, will be limited by the accurate measurement of the speed of sound profile in space and time. Any changes in temperature (thermolcine), salinity (halocline), and/or pressure (pycnocline) with depth will result in refraction (ray bending) of non-normal acoustic ray paths (Fig. 9). In order to calculate a correct depth at the proper position on the seafloor, the ray paths must be accurately modeled. Thus, if the velocity structure of the water column is not properly modeled, incorrect depth measurements will be recorded due to inaccurate time-to-depth convsersions and inaccurate modeling of non-normal ray paths. Figure 9. Diagram showing the two-way travel of a non-normal acoustic ray. Eighteen sound velocity profiles were collected throughout Bear Lake using an Applied Microsystems SVP Plus sound velocimeter. The locations of the profiles are displayed within Figure 4. Thumbnails of the sound veloicty profiles are listed below. Click on a thumbnail to view a full resolution version of the sound velocity profile. These data are also stored within the ArcView project file and as an MS Excel spreadsheet in the svp directory. See GIS Data and CD Contents for more information. Figure 4. Map showing location of grab samples and sound velocity profiles. Sound Velocity Profiles Cast 1 Cast 2 Cast 3 Cast 4 Cast 5 Cast 6 Cast 7 Cast 8 Cast 9 Cast 10 Cast 11 Cast 12 Cast 13 Cast 14 Cast 15 Cast 16 Cast 17 Cast 18

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