Color Shaded-Relief GeoTIFF Image Showing the 2-m Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H12296 in Block Island Sound (H12296_MB2M_UTM.TIF, UTM Zone 19, NAD 83)

Bathymetric data were acquired in extended Triton data format (XTF) and recorded digitally through an ISIS data acquisition system. A RESON SeaBat 7125 multibeam echosounder, with a frequency of 400 kHz, was used to collect MBES data on the Thomas Jefferson and both survey launches. All positioning and attitude were determined with Trimble DSM212L DGPS receivers and Applanix POS/MV Model 320 v.4 inertial navigation systems. The data were processed using CARIS HIPS (Hydrographic Image Processing System) software for quality control, and to incorporate sound velocity and tidal corrections. Sound velocity corrections were derived using frequent SEACAT CTD (conductivity-temperature-depth) profiles. Typically, a CTD cast was conducted every three to four hours of multibeam acquisition. Tidal zone corrections were calculated from data acquired at the Newport, Rhode Island, New London, Connecticut, and Montauk, New York tidal gauges. The vertical resolution of the multibeam data is approximately 0.5% of the water depth. The data were gridded to 2-m resolution and saved as a CARIS HIPS database. Vertical datum is mean lower low water; X and Y units are meters; UTM Zone 19, NAD83.

Using CARIS HIPS v7.1.1: Opened the CARIS project files provided by NOAA and created new Fieldsheet 'H12296_UTM19' and a new swath BASE surface '2m_bathyUTM19' with the selected survey tracklines (note, crosslines and tielines were not included in the final BASE surface). Two iterations of the interpolation algorithm within CARIS HIPS were run in a effort to fill small gaps in the dataset. Note some large gaps still occur where there was not 100% overlapping coverage collected with the multibeam system. This process step and all subsequent steps were done by the same person, Seth Ackerman.

Using CARIS BASE Editor v4.0.5: Opened the BASE Surface 2m_bathy_Interp2.csar and exported View... to GeoTIFF format (options: Ground Resolution 2m, Image Depth 24 Bit, Background Colour White (255,255,255)). Sun illumination was from the northeast at 45 degrees above the horizon. Vertical exaggeration is 5x.

Using GeoTIFFExamine (no version): Created a TFW for the GeoTIFF.

Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.

Added keywords section with USGS persistent identifier as theme keyword.