Combined 2-m and Interpolated 10-m Bathymetric Grid of National Oceanic and Atmospheric Administration (NOAA) Survey H12013 Off the Entrance to the Connecticut River in Northeastern Long Island Sound (H12013_INTGEO, Geographic, WGS-84)

Two 8.5-m aluminum Jensen launches and the NOAA Ship Thomas Jefferson were used to acquire the multibeam echosounder (MBES) bathymetric data for survey H12013 during April-May 2009 off the entrance to the Connecticut River, northeastern Long Island Sound. The MBES data on launch 3101 were collected with a hull-mounted RESON SeaBat 455-kHz 8125 shallow-water system. This system measures two-way sound travel time across a 120-degree swath. The SeaBat 8125 has 240 beams with a cross-track beam width of 0.5 degrees at nadir. The MBES data were collected aboard the ship and launch 3102 with RESON 7125 systems which measured two-way sound travel time across a 140-degree swath. Original horizontal resolution of the MBES data was 0.5 m for depths less than 20 m and 1 m for the deeper areas. Vertical resolution of the MBES data is about 0.5% of the water depth. The bathymetric data were acquired and logged with HYPACK Hysweep and processed by NOAA using CARIS HIPS (Hydrographic Image Processing System) software for quality control, to incorporate sound velocity and tidal corrections, and to produce the continuous digital terrain model. All positioning and attitude were determined with Trimble DSM212L DGPS receivers and Applanix POS/MV Model 320 v.4 inertial navigation systems; HYPACK 2009 was used for acquisition line navigation. 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 MBES acquisition. Tidal zone corrections were calculated from the tide stations at New London and New Haven, Connecticut. Vertical datum is mean lower low water. Individuals interested in detail descriptions of the MBES acquisition and processing should consult the Descriptive and Data Acquisition and Processing reports. The combined BASE-surface data were gridded to 2-m resolution and saved as a CARIS HIPS/SIPS v6.1 SP2 database in UTM Zone 18, NAD83.

Opened the 2-m fieldsheet provided by NOAA NOS (H12013_Mosaic_Complete.fsh) and a new fieldsheet H12013_sda.fsh. Ran the "Combine base surface" process to create a 10m resolution base surface (10m_combined.csar) from the 2m base surface H12013_2mCombined.csar. Ran 1 iteration of interpolation on the 10m base surface to fill the gaps and create a 100% coverage base surface (10m_combined_Interp.csar). Exported to Bathymetric Attributed Grid (BAG) file (10m_combined_Interp.bag)

Imported the BAG file (10m_combined_Interp.bag) to an IVS Fledermaus SD file (10m_combined_Interp.sd) using DMagic v.7.2. Imported SD files H12013_2m_combined.sd (created while producing the 2-m UTM grid released elsewhere in this report) and 10m_combined_Interp.sd into DMagic v.6.7 (this version used because of a bug in current version whereby the surfacemerge process is broken) and created DTM files (H12013_2m_combined.dtm and 10m_combined_Interp.dtm)

Ran the process dtmmerge to combine the DTM files (H12013_2m_combined.dtm and 10m_combined_Interp.dtm), creating the DTM file outtemp67.dtm using the IVS v.6.7 FMCommand (dtmmerge -in H12013_2m_combined.dtm 10m_combined_Interp.dtm -out outtemp67.dtm -cellsize 2 -mode highres) This was done to create a merged DTM that would essentially preserve the 2 meter resolution where it exists, and fill the gaps with data from the interpolated 10 meter grid. The input order doesn't matter because the command specified "-mode highres" which gives priority to the higher resolution input dataset.

Using IVS Fledermaus DMagic v.7.2, imported output of the dtmmerge process (outtemp67.dtm) to a SD file (outtemp67.sd) and exported the SD surface to an ArcView Grid (2m_interp.asc) This is done to convert the new merged DTM into an SD file, so that it could be then converted to an ArcView grid.

Using ArcCatalog v.9.3, converted ArcView Grid (2m_interp.asc) to ESRI 32-bit floating point grid: h12013_intutm (ArcToolbox - Conversion Tools - To Raster - ASCII to Raster) and defined projection for grid h12013_intutm as NAD83 UTM zone 18 (ArcToolbox - Data Management Tools - Projections and Transformations - Projection). The output data type chosen was "float".

Projected the raster grid h12013_intutm to Geographic coordinate system WGS84 datum creating the grid h12013_intgeo using ArcCatalog v.9.3. (ArcToolbox - Data Management Tools - Projections and Transformations - Raster - Project Raster) Parameters used were the default values.

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 distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The geodetic model information was moved to the appropriate place. 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.