Science Applications International Corporation's (SAIC) ISS-2000 acquires,
processes and records data, provides survey control and underway quality
control displays. SAIC's SABER processing software is used to process the
raw soundings, analyze the results, manually edit the sounding data to remove
outliers and derive average gridded data values. Additional data acquisition
and processing information can be found in the metadata for cruises HI0602.
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 gsf2bs program (July, 2005) converts the swath bathymetry ping records contained
within a GSF (Generic Sensor Format) version 2.02 dataset into bs file 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 comparing travel times of beams adjacent to the gap, assigning the position
using the adjacent sample closest to nadir, and averaging the interpolated values that
fall within a cell. 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 GeoTIFF's. For more information on the backscatter
processing technique see <
http://www.soest.hawaii.edu/pibhmc/pibhmc_documentation.htm>.
Software_Used:
SAIC ISS-2000 Acquisition Software, v 3.4
SAIC SABER Processing Software, v 3.3.15
Hawaii Mapping Research Group (HMRG) Processing Software
GMT Generic Mapping Tools, v 4.1
MB System, v 5.0.7