United States Geological Survey (USGS), Coastal and Marine Geology (CMG), Chief Scientist (Peter Dartnell) 2004 XYZ ASCII XYZ ASCII format data generated from the 1996 multibeam sonar survey of Santa Monica Bay, California. The data include high-resolution acoustic, calibrated backscatter. These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) or other software to display acoustic backscatter data of the Short Bank Region, Santa Monica Bay, California.. Information for USGS Coastal and Marine Geology related activities are online at < http://walrus.wr.usgs.gov/infobank/c/c196sc/html/c-1-96-sc.meta.html > < http://geopubs.wr.usgs.gov/open-file/of02-162/ > 19960930 19961029 ground condition Complete As needed -118.65038847 -118.48874155 33.94368538 33.82901158 GCMD DIF, Version 5.0a, September 1996: Parameter Keywords Earth Science > Oceans > Bathymetry/Seafloor Topography > Bathymetry Earth Science > Oceans > Bathymetry/Seafloor Topography > Water Depth None Marine Geology Multibeam Bathymetry Water Depth Seafloor Topography Geographic Names Information System, USGS, Reston, VA Santa Monica Bay None CA Southern California USA None Please recognize the U.S. Geological Survey (USGS) as the source of this information. USGS-authored or produced data and information are in the public domain. Peter Dartnell United States Geological Survey (USGS) Coastal and Marine Geology (CMG) Physical Scientist mailing and physical address

USGS, MailStop 999, 345 Middlefield Road

Menlo Park CA 94025-3561 USA (650) 329-5460 (650) 329-5411 pdartnell@usgs.gov Not determined. Point features present. Complete 0.5 meters 0.05 percent of the water depth. Depths corrected to mean lower low water datum. The multibeam bathymetry and acoustic backscatter data were collected along a continuous swath perpendicular to the direction of the ship using a Kongsberg Simrad EM1000 multibeam sonar system. The data were cleaned of bad navigation and depth readings and corrected for tides to mean lower low water datum. Acoustic backscatter strength was converted from decibels (dB) to a non-dimensional digital number (DN) using the conversion, "Absolute Value(2DN/dB)", where DN ranges from 0 to 255 and dB ranges from 0 to -127. The acoustic backscatter values were gridded into a common grid. The gridded data were converted to ArcInfo GRID format using ArcInfo's ASCIIGRID command.The GRID was converted to an XYZ ASCII file by using the GRIDPOINT, ADDXY, and Tables' UNLOAD commands. 19961030 Peter Dartnell United States Geological Survey (USGS) Coastal and Marine Geology (CMG) Physical Scientist mailing and physical address

USGS, MailStop 999, 345 Middlefield Road

Menlo Park CA 94025-3561 USA (650) 329-5460 (650) 329-5411 pdartnell@usgs.gov Point Point 0.00008 0.00008 Decimal degrees WGS84 WGS84 6378137.00 meters 0.003352811 Sample of Backscatter XYZ ASCII file > Longitude, Latitude, DN Value >(decimal degree, decimal degree, DN value) >-118.67421,33.63640,207.696 >-118.67413,33.63640,206.398 >-118.67405,33.63640,203.770 >-118.67398,33.63640,201.170 >-118.67390,33.63640,201.098 >-118.67382,33.63640,202.064 >-118.67374,33.63640,202.693 >-118.67367,33.63640,202.720 >-118.67444,33.63640,201.992 none United States Geological Survey (USGS) Information Services mailing and physical address

345 Middlefield Rd., MS-999

Menlo Park CA 94025 USA (650)329-5460 C-1-96-SC data set These data not intended for navigational purposes. Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user. Neither the U.S. Government nor any agency thereof, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy. ASCII none None 20031216 Peter Dartnell United States Geological Survey (USGS) Coastal and Marine Geology (CMG) Physical Scientist mailing and physical address

USGS, MailStop 999, 345 Middlefield Road

Menlo Park CA 94025-3561 USA (650) 329-5460 (650) 329-5411 pdartnell@usgs.gov Content Standard for Digital Geospatial Metadata ("CSDGM version 2") FGDC-STD-001-1998 universal time