Multibeam bathymetry data collected in 2016 in Catalina Basin, southern California

The USGS, PCMSC received the Kongsberg EM-300 line files from the University of Washington. The line files were imported into Caris HIPS and SIPS (version 9.0) software. The survey line files all had time stamps of July 1996 dates not February 2016 dates. Once all Caris software references were changed to the 1996 dates the lines imported correctly. It was assumed that vessel lever arm offsets and water column sound velocity corrections were applied in the original line files. Verified 6-minute interval MLLW water levels were downloaded for the harmonic Los Angeles tide station 9410660. The water levels were converted to the subordinate Avalon tide station by adding 8 minutes to the times and 0.29m to the water levels (https://tidesandcurrents.noaa.gov/noaatidepredictions.html?id=9410079&legacy=1). The water levels were applied to the data and the bathymetry soundings were cleaned of obvious bad soundings and manual refraction corrections were applied to some lines. The data were gridded into a 10-m base surface using the Swath Angle method. The surface was exported to an ASCIIRaster file in UTM-11 coordinates referenced to WGS84, mean lower low water. The ASCIIRaster file was imported into a GIS (ESRI, ArcMap) and converted to a TIFF image.

Edits were made to delete extraneous text in the Denominator of Flattening Ratio tag, and to change the Point of Contact and Metadata Contact to static contact information for PCMSC. No data were changed.

Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.

Edited metadata to perform minor edits, correct typos, and bring the file up to PCMSC metadata standards. No data were changed.