Elephant seal with CTD tag. Photo credit: Chris
Oosthuizen
Australian climate and ocean scientists are studying some of
the planet's most remote areas using a multi-million dollar
array of high-tech underwater equipment that provides data vital
for the monitoring of almost one-third of the world's oceans.
The kit of technology includes sensor floats and autonomous
underwater vehicles, which combine with sensor tagged animals,
moored scientific stations and satellite remote sensing to form
the Integrated
Marine Observing System (IMOS).
All data collected by IMOS is available free at the
institution's webportal, the IMOS Ocean Portal. The integration
of this data and its online presentation at the IMOS Ocean
Portal represents big step forward in climate science.
"This is a unique approach to monitoring the linkage between
the physical properties of oceans, such as temperature and
salinity, and how they influence the marine ecosystem,"
Oceanographer and leader of the IMOS ocean and climate node Dr
Susan Wijffels said.
IMOS brings together ocean and climate scientists from
research institutions across the globe, including the University
of Tasmania, the Commonwealth Scientific and Industrial Research
Organisation (CSIRO), Australian Antarctic Division, Bureau of
Meteorology, Australian Institute of Marine Science, Sydney
Institute of Marine Science, and University of Western
Australia. There is also continued collaboration with northern
hemisphere partners, including the United States, France, the
United Kingdom, and Korea.
Dr Wijffels, believes IMOS is helping to foster cooperation
between scientific disciplines that have not traditionally
worked together.
"What is happening in the open ocean is vitally important to
all Australians and their understanding of local and regional
climate," IMOS Director, Tim Moltmann said. "It drives our
climate and weather extremes, is the workplace for offshore
industries and maritime defence activities and contains a
diversity of marine life that currently is barely described. We
need to observe this part of the earth system to understand how
it's changing, and what the impacts might be on current and
future generations."
The technology
Agro Floats
Argo floats measure temperature and salinity between the
ocean's surface and a depth of 2000 m (6500 ft) every 10 days.
This data is streamed in real-time to the IMOS Ocean Portal and
quality-controlled data is released after six months. The Argo
floats provide essential data for ocean and climate research and
prediction. Argo Australia is operated by CSIRO Marine and
Atmospheric Research based in Hobart, Tasmania with operational
support from the Bureau of Meteorology and financial support
from IMOS.
Argo floats change their buoyancy by driving oil from inside
the float to an external bladder using an electric motor and
battery pack. This alters the floats volume and density relative
to the surrounding seawater letting in move vertically through
the water column. The Argo floats also drift with the ocean
currents providing information on the direction and speed of the
ocean's flow, or the Lagrangian velocity as it is known.
Deep Ocean Gliders
The IMOS project has a fleet of eight unmanned ocean glider
vehicles. These are given GPS waypoints and with the aid of an
onboard computer, they glide between these points using vertical
movement by regulating buoyancy and horizontal movement using a
combination of wings, which give the gliders forwards motion,
and a shifting weight, which allows the vehicles to roll and
therefore turn. The glider travels at speeds of around 30-40
cm/s (~0.5 knot) and can be controlled at any time by scientists
via satellite.
Data captured by the gliders includes temperature, salinity,
dissolved oxygen, turbidity, chlorophyll and depth. Average
water velocities can also be interpreted by seeing how far from
its expected course the glider has drifted. Researchers have an
option to add extra sensors to the gliders to tailor what
observations are being made.
The IMOS project has two class of gliders the Slocum gliders
and Seagliders. Slocum are currently equipped with a
Seabird-CTD, WETLabs BBFL2SLO 3 parameter optical sensor
(measuring Chlorophyll-a, CDOM & 660nm Backscatter) and an
Aanderaa Oxygen optode. The Seagliders are fitted with a
Seabird-CTD, WETLabs BBFL2VMT 3 parameter optical sensor
(measuring Chlorophyll-a, CDOM & 660nm Backscatter) and a
Seabird Oxygen sensor.
Autonomous Underwater Vehicle (AUV)
The IMOS AUV Facility is lead by the University of Sydney's
Australian Centre for Field Robotics. The Facility a Autonomous
Underwater Vehicle (AUV) called Sirius used for undertaking high
resolution stereo survey work. It is a modified version of a
mid-size robotic submarine called Seabed built at the Woods Hole
Oceanographic Institution. It is equipped with a range of
oceanographic instruments, including a high resolution stereo
camera pair and strobes, a multibeam sonar, depth and
conductivity/temperature sensors, Doppler Velocity Log (DVL)
including a compass with integrated roll and pitch sensors,
Ultra Short Baseline Acoustic Positioning System (USBL) and
forward looking obstacle avoidance sonar. Sirius has a maximum
depth rating of 700m (2300ft), has a propulsion system
consisting of three 150W brushless DC thrusters powered by a 1.6
kWh Li-ion battery pack.
Animal Tagging
The Australian Animal Tagging and Monitoring System (AATAMS)
uses acoustic technology, CTD satellite trackers and bio loggers
to monitor coastal and oceanic movements of marine animals from
the Australian mainland to the sub-Antarctic islands and as far
south as the Antarctic continent. AATAMS is set up to collect
data over a long period of time to enable researchers to assess
the effects of climate change, ocean acidification and other
physical changes on animals within the marine environment.
Currently a large range of fish, sharks and mammals including
seals are used. Information collected includes behavioural and
physical data such as the depth, temperature, salinity and
movement of individual marine animals. Real-time data is
available free of charge at the IMOS Ocean Portal.
Other technology
A number of other technologies are used in the IMOS program
including the so-called ships of opportunity, various moored
observation stations and satellite remote sensing.
IMOS is supported by the Australian Government, through the
National Collaborative Infrastructure Strategy and the Super
Science Initiative. It is led by the University of Tasmania on
behalf of the Australian marine and climate science community.
CSIRO is the lead institution for the IMOS ocean and climate
node.
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