Bathymetry and Acoustic Backscatter Data Collected in 2010 from Cat Island, Mississippi

• Abstract
• Introduction
• Survey Overview
• Data Acquisition
• Single-Beam Bathymetry
• Swath Bathymetry
• Backscatter/
  Side-Scan Sonar
• Data Processing
• Error Analysis
• Survey Products
• Data Downloads
• Logs
• Acronyms
• Acknowledgments
• References

DATA ACQUISITION – SINGLE-BEAM BATHYMETRY

Differentially Corrected Navigation and Motion

The GPS base station was assembled at the pre-existing National Geodetic Survey (NGS) Benchmark BH08 at Point Cadet, Miss. (fig. 5.). GPS receivers recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from the satellites via the Thales choke-ring antenna. This GPS instrument combination was duplicated on the survey vessel (rover). The base receiver and the rover receiver recorded their positions concurrently at 1-second (s) recording intervals throughout the survey period. Boat motion was recorded at 50-millisecond (ms) intervals using a Teledyne TSS Dynamic Motion Sensor – 05 (TSS DMS-05) (table 1).

Soundings

Aboard the RV Streeterville, depth soundings were recorded at 50-ms intervals using a Marimatech E-SEA SOUND 103 echosounder system with dual 208-kilohertz (kHz) transducers (fig. 5) (table 2). The single-beam bathymetry was acquired using HYPACK® version 10 (HYPACK, Inc.), a marine surveying, positioning, and navigation software. Data from the GPS receiver, motion sensor, and fathometer were streamed in real time to a laptop computer. HYPACK acquisition combines all input data into a single raw data file, with each device string referenced by a device identification code and time stamped to the nearest millisecond. The software also manages the planned-transect information, providing real-time navigation, steering, correction, data quality, and instrumentation-status information to the boat operator.

Sound Velocity

Sound velocity measurements were collected using an Applied Microsystems Smart sound velocity profiler (SVP). The average measurement for the survey was 1,524 meters/second (m/s).