Color Shaded-Relief GeoTIFF Image Showing the 2-m Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H11999 North of Duck Pond Point, New York (H11999_MB2M_GEO.TIF, Geographic, WGS84)

Bathymetric data were acquired in extended Triton data format (XTF) and recorded digitally through an ISIS data acquisition system. Reson 8101, 7125, and 8125 multibeam echosounders hull-mounted on two 29' launches and 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 New London, CT, and New Haven Harbor, CT, 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 18, NAD83.

A color, hill-shaded GeoTIFF image with a world file was exported from CARIS HIPS/SIPS software version 7.0 in the UTM projection of the original field sheets (UTM zone 18N, horizontal datum NAD83). Sun illumination is from the north at 45 degrees above the horizon, and vertical exaggeration is 5x.

The UTM projected GeoTIFF was imported into ArcGIS v9.3 and reprojected using the data management tool Project Raster (ArcToolbox, Data Management Tools, Projections and Transformations) from UTM Zone 18N, NAD 83 to Geographic, WGS84. The options specified in the Project Raster tool were:

1. Input coordinate system:  NAD_1983_UTM_Zone_18N
2. Output coordinate system:  GCS_WGS_1984         
3. Geographic transformation method:  NAD_1983_WGS_1984_5         
4. Resampling technique: BILINEAR         
5. Output cell size: 0.000022 (decimal degrees, default as calculated by ArcMap for a 2 meter cell size)          

The geographic transformation selected is the most accurate one provided by ESRI as it ties in WGS84 with ITRF96, thus reflecting the earth centered offset (x-y-z) between WGS84 and NAD83 (from the ESRI Knowledge Base Document Number 24159).

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.). Both geographic and a planar coordinate system were present, the planar one was removed with the resolution transferred to the geographic. In the case of the depth resolution, the value of 9999 was entered to indicate that the original metadata did not contain the required information. The link to the data in the Distribution_Information section had to be 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.