Equipment serial numbers and software versions are as follows:
RESON 8101-ER multibeam echosounder DOC inventory #: CD0000537418 Firmware, dry: 8101-2.07-2D4D Firmware, wet: 8101-1.06-2F6B
POS/MV Model 320, version 3 DOC inventory #: CD0000476647 PCS serial #: 474 IMU serial #: 203 Controller software: v 188.8.131.52
Seabird SBE19 CTD: Serial #: 3029
R/V AHI Lever Arm Distances and Alignment Offsets The R/V AHI Reference Point (RP) is defined to be the intersection of the vessel's centerline, the cabin deck and the bulkhead immediately aft of the transducer. This is marked by a punch in the deck weld at that location. Positive X means the point is forward of the RP, positive Y means the point is to starboard of the RP, positive Z means the point is below the RP. The loaded waterline is defined as the intersection of the vessel's performance wing with the hull at the transom.
Antenna Baseline Distance, m: 1.229 Transducer depth below waterline, m 0.62
RP to IMU 0.80 0.00 0.08 RP to Primary GPS Antenna -3.55 -0.61 -1.88 RP to Vessel 0.16 0.00 0.77 RP to Sensor 1(MB transducer) 0.16 0.00 0.77 RP to Sensor 2 0 0 0 RP to Aux. GPS Antenna 0 0 0 RP to Heave lever arm(deg) -0.67 0.00 0.00 IMU rotation Ref. Frame, deg 0 0 0 Sensor 1 rotation Ref. Frame, deg 0 0 0 Sensor 2 rotation Ref. Frame, deg 0 0 0
Roll offset: +0.5 deg Pitch offset: 0.0 deg Gyro offset: 0.0 deg
The data have been corrected for observed tides from Guam tide gauge 1630000 with a time corrector of 18 minutes and a tide height multiplier of 0.94 using SABER postprocessing software. The data were also recorrected for observed sound velocities in postprocessing.
Hawaii Mapping Research Group (HMRG) processing software was then used to extract values of acoustic intensity from the soundings. HMRG is an organization of scientists, engineers and technicians whose mission is to design, build, and operate tools for mapping the seafloor. HMRG is a group within the School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa. The gsf2mr program (July, 2003) converts the swath bathymetry ping records contained within a GSF (Generic Sensor Format) version 2.02 dataset into mr1file format. This is done as follows: (i) position each beam's bottom detect intensity sample at the across-track location of that beam's bathymetry value; (ii) assuming a flat bottom in the near neighborhood of the beam, compute across-track distances for all of the beam's remaining intensity samples based on their temporal relation to the bottom detect sample and the computed average sound velocity for that beam as derived from its range and travel time; (iii) after all of the intensity samples from all beams of a ping have been located in across-track distance, fill the gaps between them as necessary by interpolation.
The conversion described above is necessary in order to run HMRG backscatter processing operations on the data, such as filtering to remove noise, and to create netCDF grids, raster images and geotiffs.
GMT was then used to reformat the acoustic imagery when necessary. Interactive Visualization System's Fledermaus, ESRI ArcGIS, and RSI ENVI were used for viewing results and creating browse objects.
Software used: SAIC ISS-2000 Acquisition Software, v 3.4 (20030610) SAIC SABER Processing Software, v 2.0.2 (20030610) Hawaii Mapping Research Group (HMRG) Processing Software GMT Generic Mapping Tools, v 3.4.2 (20021002)
More information can be be located at <http://unidata.ucar.edu/packages/netcdf/index.html>
List of Manua backscatter netCDF grid files: manua-8-01.grd.zip manua-8-02.grd.zip manua-8-03.grd.zip manua-8-04.grd.zip manua-8-05.grd.zip manua-8-06.grd.zip manua-8-07.grd.zip
List of Manua backscatter GeoTIFF files:
manua-8-01.zip manua-8-02.zip manua-8-03.zip manua-8-04.zip manua-8-05.zip manua-8-06.zip manua-8-07.zip