These Multibeam Summary Products are generated by the Okeanos Explorer's Mapping Data Team at the Center for Coastal and Ocean Mapping Joint Hydrographic Center (CCOM/JHC) at the University of New Hampshire (UNH).

These products are produced after each NOAA Ship Okeanos Explorer mission.

Data Acquisition Steps: The bathymetry data were generated using a Kongsberg EM304 MKII multibeam system (0.5 x 1 degree array), and recorded using Kongsberg's Seafloor Information System (SIS) software version 5.6 as *.kmall files. Collocated to the bathymetric data, bottom backscatter data were collected and stored within the *.kmall files, both as beam averaged backscatter values, and as full time series values (snippets) within each beam. Real-time corrections to the data upon acquisition included: continuous application of surface sound speed obtained with a Reson SVP-70 sound velocity probe mounted next to the multibeam transducer face or a SBE 45 thermosalinograph flow through system with a hull-mounted intake, application of sound speed profiles obtained with Sippican Deep Blue Expendable Bathythermographs (XBTs) and/or Seabird CTD 9/11, application of roll, pitch, and heave motion corrections obtained with POS MV 320 version 5 inertial motion unit using Marine Star DGPS corrector values. No tidal corrections were applied to the raw or processed data. 

Data Processing Steps: The full-resolution multibeam .kmall files (Level-00 data) were imported into QPS Qimera version 2.3.4, and then processed and cleaned of noise and artifacts. Each line of cleaned full resolution data was exported to a .gsf file (Level-01 data). 

Data Product Production Steps:The processed and cleaned files were used to create a static surface in QPS Qimera. This final surface was re-projected into the field geographic WGS84 reference frame in QPS Fledermaus software version 7.8.11 and saved as a .sd file for archiving. Using QPS Fledermaus 7.8.11, this .sd bathymetric grid file was then exported into ASCII XYZ text, color .tif, floating point .tif, and Google Earth .kmz file formats - all referenced to WGS84 (Level-02 data). There is a complete accounting of each individually archived multibeam data file and of each bathymetric surface product in the multibeam data acquisition and processing logs archived with the dataset. Some cruises have several final multibeam grid files in order to keep file sizes manageable and to focus on particular survey areas of interest. The *.sd file format was selected for its ability to be viewed using the free viewer version of Fledermaus software distributed by QPS. Geotiffs, .xyz ASCII files, and KMZs can be read by the freeware Google Earth and Google Earth Pro.

In some cases level-02 Fledermaus scene files used for remotely-operated vehicle dive planning are included in archived data sets. A scene file is a combination of .sd files saved into a single file. To create these multi-layer scene files, a number of additional field processing steps were performed on a subset of the multibeam files. Bathymetric .sd files were run through the "compute slope" function in Fledermaus to generate seafloor slope maps. Fledermaus Geocoder Tool version 7.9.5 was used to create bottom backscatter mosaic .sd files. The mosaics were then draped over the bathymetric .sd file using the "attach scalar to surface" function in Fledermaus. ROV dive track points were placed on the seafloor in Fledermaus using the geo-picking tool, and were saved as a points layer in the scene file. In some cases, selected water column multibeam backscatter files (.kmwcd) were processed using QPS Qimera, and anomalies such as suspected seep locations were identified and exported as Fledermaus .sd files. Scene files are viewable in the free QPS Fledermaus Viewer software.

Please do not hesitate to contact the Okeanos Mapping team (oar.oer.exmappingteam@noaa.gov) with any questions regarding these files.

If you are interested in downloading the raw data (level-0) or cleaned/edited data (level-1), you can access those data from the NOAA National Data Center for geophysical data.  http://www.ngdc.noaa.gov/mgg/bathymetry/multibeam.html

For questions or assistance, OER’s Data Management Team can be reached at oer.info.mgmt@noaa.gov.