Interpolated digital elevation model (DEM) of the nearshore around Ship, Horn, and Petit Bois Islands, Mississippi: 2016

For the IFB: The manufacturer's stated vertical accuracy of Marinestar GPS subscription is 15 cm, 95% of the time. The Coda Octopus F190R+ inertial measurement unit (IMU), which integrates the Marinestar position with motion, measures vessel velocity (+/- 0.014 meters/second [m/s]), roll and pitch (less than 0.025 degrees), heading (1 m baseline 0.1 degrees), and heave (5 cm per meter (m) of depth). The vertical accuracy for the SWATHplus-H system varies with depth and across track range.
The IFB data was transformed three times using VDatum version 3.6. The vertical transformation error reported by VDatum are the following: 1) Transformation from ITRF08 to ITRF00 (equivalent to at the centimeter level WGS84_G1150) is 0.000 m or 0.000 cm for the vertical area named CONUS (Conterminous U.S.). The additional, non-VDatum, reference located at the following link lists transformation from ITRF08 to ITRF00 as -0.01050 m or -1.050 cm (https://confluence.qps.nl/download/attachments/29856813/ITRF_Transformation_Parameters.xlsx); 2) Transformation from ITRF00 to NAD83, NAVD88 with respect to GEOID12B is 0.0762 m or 7.62 cm for the vertical area named GEOID12B, and 3) Transformation from NAD83, NAVD88 with respect to GEOID12B to NAD83, MLLW is 0.163 m or 16.30 cm for the vertical area named LAmobile02-8301.
For the SBB: All static base station sessions for 202Q and WHRN were processed through On-Line Positioning User Service (OPUS) maintained by the National Oceanic and Atmospheric Administration (NOAA) and the National Geodetic Survey (NGS). The base location results from OPUS were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height). Base-station positional error for each GPS session was calculated as the absolute value of the final position minus the session position value. SPCMSC standards define the maximum acceptable vertical error for any individual base station GPS session as less than or equal to three times the standard deviation of the ellipsoid height; any occupations exceeding this error are removed and the base station coordinates are recalculated. For 202Q base location, the standard deviation of the ellipsoid height was 0.010 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.023 m. For WHRN base location, the standard deviation of the ellipsoid height was 0.002 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.022 m. For 4756 F 2011 base location only one OPUS session was run so the published coordinates were used and reported a vertical error of +/- 0.017 m.
The SBB data was transformed from ITRF00 to NAD83, NAVD88 with respect to GEOID12B using VDatum version 3.6. The vertical transformation error reported by VDatum is 0.0762 m or 7.62cm for the vertical area named GEOID12B.