Nearshore bathymetry data from northern Monterey Bay, California, September 2017
Dates
Publication Date
2017
Start Date
2017-09-17
End Date
2017-09-20
Citation
Stevens, A.W., Logan, J.B., Snyder, A.G., Hoover, D.J., Barnard, P.L., Warrick, J.A., 2017, Beach topography and nearshore bathymetry of northern Monterey Bay, California: U.S. Geological Survey data release, https://doi.org/10.5066/F76H4GCW.
Summary
This portion of the USGS data release presents bathymetry data collected during surveys performed in northern Monterey Bay, California in September 2017 (USGS Field Activity Number 2017-678-FA). Bathymetry data were collected using two personal watercraft (PWCs) equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. The sonar systems consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9° beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounders were computed using sound velocity profiles measured using a YSI CastAway CTD during the survey. Positioning of the survey [...]
Summary
This portion of the USGS data release presents bathymetry data collected during surveys performed in northern Monterey Bay, California in September 2017 (USGS Field Activity Number 2017-678-FA). Bathymetry data were collected using two personal watercraft (PWCs) equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. The sonar systems consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9° beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounders were computed using sound velocity profiles measured using a YSI CastAway CTD during the survey. Positioning of the survey vessels was determined at 10-Hz using Trimble R7 GNSS receivers and Zephyr 3 antennas operating in autonomous mode. Output from the GNSS receivers and sonar systems were combined in real time on the PWC by a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing PWC operators to navigate along survey lines at speeds of 2–3 m/s.
Survey-grade positions of the PWCs were achieved with a single-base station and differential post-processing. Positioning data from the GNSS receivers were post-processed using Waypoint Grafnav to apply differential corrections from a GNSS base station with known horizontal and vertical coordinates relative to the North American Datum of 1983 (2011 realization). Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12a offsets. Bathymetric data were merged with post-processed positioning data and spurious soundings were removed using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB.
The average estimated vertical uncertainty of the bathymetric measurements is 9 cm. The final point data from the PWCs are provided in a comma-separated text file and are projected in cartesian coordinates using the UTM Zone 10 North, meters coordinate system.
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mb17_sept_pwc_metadata.xml Original FGDC Metadata
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mb17_sept_pwc.csv “Comma-separated text”
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Purpose
Data were obtained to document changes in shoreline position and coastal morphology as they relate to episodic (storms), seasonal, interannual, and longer (for example, El Niño) processes. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify topographic and shallow-water bathymetric features.
