Home' Navy News : June 24th 2010 Contents Fleet Network Pty Ltd D/L No. 20462
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June 24, 2010
With the Australian Hydrographic Service celebrating its 90th anniversary this
month, the Navy News team thought it would be timely to bring you some
of the technological innovations enhancing our knowledge of the undersea
environment. The information here comes courtesy of a presentation delivered by
Commandant ADFA, CDRE Bruce Kafer, at the recent Oceans 10 IEEE conference
in Sydney. The presentation, entitled 'Understanding the oceans -- A Navy
perspective', was prepared in collaboration with DSTO's Dr Brian Ferguson, Dr
Philip Chapple and Jamie Watson.
Charting Earth's final frontier
The LADS measures
depth by using two laser
beams to compare the
distances to the sea
surface and sea floor.
Laser Airborne Depth Sounder
SINCE 1992 Navy has utilised
DSTO-invented Light Detection
and Ranging (LIDAR) technol-
ogy, fitted aboard an airplane
(Navy's only fixed-wing aircraft),
to chart littoral regions, where the
water is shallow and relatively
Known as the Laser Airborne
Depth Sounder (LADS), the system
emits an infrared laser beam, which
is reflected at the sea surface, while
a second, blue-green beam is partly
reflected at the sea floor. The system
measures the difference between
arrival times of the two reflected
beams to compute the water depth.
LADS is so effective at surveying
clear, shallow waters (such as the
Great Barrier Reef and Torres Strait)
that surface units are no-longer rou-
tinely tasked in these areas.
EFFICIENCY: A LADS
survey of a section of the Great
Barrier Reef, near Townsville.
SAFER WATERWAYS: AEMB (left) versus LADS (right) surveys of Warrior
Reef, Torres Strait.
Airborne Electromagnetic Bathymetry
LASER Airborne Depth Sounding's
main limitation is it doesn't perform
as well in turbid or murky waters.
In response, DSTO has more recently
developed and demonstrated an Airborne
Electromagnetic Bathymetry System
(AEMB) -- a shallow-water system that
overcomes LIDAR's significant limita-
tions in surveying turbid waters.
In the future this technology may
also be applied in bubble-filled surf zone
waters, where sonar depth sounding sys-
tems do not perform optimally.
Multibeam Echosounder Imaging
THE depth and characteristics of the
seabed can only be effectively mapped
for a broad range of oceanographic
conditions using acoustic techniques.
Multibeam Echosounder sonars are
primarily used to chart seafloor topogra-
phy, but they can also be used to detect
and locate hazards.
wreckage of a RAN
Fairey Firefly rest-
ing on the bottom of
Jervis Bay, identi-
fied via Multibeam
THREE years ago a collaborative
project involving Navy, CSIRO and
the Bureau of Meterology produced
an ocean forecasting system called
BLUElink combines climatology
databases, satellite remote sensing
and at-sea data to produce three-
dimensional ocean forecasts, includ-
ing ocean currents, wind stress, tem-
perature and salinity.
INNOVATION: A BLUElink image
of the Indian Ocean and West
Australian coast from Carnarvon
to Cape Leeuwin.
The colour depicts variations in
sea temperature with the arrows
indicating particular currents.
BLUElink ocean forecasting system
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