Color Shaded-Relief GeoTIFF Image Showing the 2-m Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H12023 in Block Island Sound (H12023_MB2M_GEO.TIF, Geographic, WGS84)

Bathymetric data were acquired in extended Triton data format (XTF) and recorded digitally through an ISIS data acquisition system. A RESON 7125, hull-mounted on the NOAA ship Thomas Jefferson and one 8.5-m launch and a RESON 8125 multibeam echosounder, mounted on another 8.5-m launch deployed from the NOAA ship Thomas Jefferson, were used to acquire the sounding data. 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.

The H12023 CARIS HIPS base surface H12023_Combined_2m_CUBE_Deep_Final (fieldsheet H12023_Combined) was opened in CARIS HIPS/SIPS v7.0 and exported as a GeoTIFF image (24-bit, compressed format) using the CARIS HIPS Export Wizard. Sun illumination was from the north at 45 degrees above the horizon. Vertical exaggeration is 5x.

Created a world file from the GeoTIFF supplied by NOAA using GeoTIFF Examiner. This process step and all subsequent steps were performed by the same person, Katherine McMullen.

Reprojected dataset from UTM Zone 19, NAD 83 to geographic, WGS84 using ArcGIS Project Raster tool (ArcGIS 9.3) using geographic transformation 1 and remaining default settings.

Using Adobe Photoshop CS2, selected and filled triangles at outer margins of image (created when image was reprojected) with white using the paint bucket tool and saved without applying compression.

Used GeoTIFF Examiner to update the header of the TIFF to contain the georeferencing information from the world file, making the image a GeoTIFF.

Defined projection as Geographic, WGS84 using Define Projection tool in ArcGIS 9.3.

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.