Grayscale TIFF Image of the 1-m Sidescan-Sonar Data From National Oceanic and Atmospheric Administration (NOAA) Survey H12013 off the entrance to the Connecticut River in northeastern Long Island Sound (H12013_1MSSS_UTM18.TIF, UTM Zone 18, NAD83)

The sidescan-sonar data were acquired with a Klein 5000 high-speed sidescan-sonar system hull mounted to 8.5-m aluminum launches deployed from the NOAA ship Thomas Jefferson. The system consists of a Klein 5500 towfish, a Transceiver/Processing Unit (TPU), and a computer for user interface; has an operating frequency of 455 kHz; and was set to sweep 100 m to either side of the launch tracks. The Klein 5000 system is distinct from other commercially-available side scan sonars in that it forms 5 simultaneous, dynamically-focused receiver beams per transducer face. This improves along-track resolution to approximately 30cm at the 100m range scale, even when acquiring data at up to 10 knots. Across-track resolution is typically 7.5cm at the 100m range scale. The achievable 30cm resolution meets the NOAA Hydrographic Surveys Specifications and Deliverables Manual (HSSDM) for object detection. Klein SONARPRO was used to acquire the Klein 5000 sidescan sonar data; CARIS SIPS (Sidescan Image Processing) software was used to process the sidescan data and to produce a composite sidescan-sonar image at 1-m horizontal resolution and projected into UTM Zone 18 NAD83.

The image was imported into Adobe Photoshop CS2 in order to apply a linear stretch (i.e., increase the dynamic range of the data), to change image from RGB to 8-bit grayscale, to invert the grayscale to make strong reflections light tones and weak reflections returns darker tones, and to assign a 'NO DATA' value (255).

The world (.tfw) file was renamed to match the new GeoTIFF name and GeoTIFFExamine was used to add the georeferencing information to the TIFF making the image a GeoTIFF.

ArcToolbox -Data Management Tools - Projections and Transformations - Define Projection Tool was used to define projection as UTM Zone 18 NAD83 in ArcGIS 9.2.

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 link to the browse graphic was fixed, and a folder link in the distribution section was also fixed. 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.