New Breed of Sensors
Gliders, floats provide persistent underwater surveillance
By EDWARD LUNDQUIST, Special Correspondent
important in research as well as a
broad range of operational and
education applications. Satellites
can watch from above for long
periods of time. But timely situational reporting in the oceans
requires specialized systems to stay
at sea for long periods of time
while collecting and returning useful information.
The 3,000-plus operational
floats in the Argo network are collecting vertical profiles of marine
environmental data — temperature, salinity and velocity — in
nearly every part of the world’s oceans (except those
under permanent ice cover), according to Dean
Roemmich, a physical oceanographer at Scripps
Institution of Oceanography at the University of
California-San Diego. The data helps scientists understand the effects of the ocean properties and develop
forecasts. All Argo data is free and immediately available via Argo’s website: www.argo.net.
The Argo program is a collaboration of 50 research
and operational agencies from nearly 30 countries —
the United States has contributed roughly half of the
floats in the array, according to the Argo website. The
project is overseen by an International Argo Steering
Team and a Data Management Team that comprises
representatives of float-providing countries. Argo
deployments began in 2000 and the array was completed by November 2007.
To maintain the array’s 3,000-plus float capability,
the program needs to deploy about 800 replacement
floats per year, at a total cost of about $24 million,
according to the Argo website. Floats are paid for by
their contributing country.
The Argo float system is a drifting buoy that can
dive, drift with currents, then surface to collect and
transmit environmental data for scientific research.
Collecting accurate environmental data is especially challenging
at sea, where sources of data are limited.
■ Unmanned floats and gliders can conduct long-term surveillance missions.
■ Wave gliders use wave motion for propulsion and solar energy
to power electronics.
■ Unmanned systems can be launched and recovered from submerged submarines
Unmanned systems and distributed remote sensors are becoming more common for con- ducting battlespace awareness. While some
systems provide information about potential targets,
others provide accurate environmental data. Filling the
need for this information — from lots of places all the
time — is especially challenging at sea, where sources
of data are limited.
A variety of tools and platforms can help conduct
persistent underwater surveillance and data collection
in areas of interest when a ship or submarine needs to
be somewhere else. Unmanned surface vehicles (USVs)
and unmanned underwater vehicles (UUVs) come in
many shapes and sizes for a variety of missions.
As surveillance platforms, their usefulness may be
constrained by power, persistence or payload limitations. Some can be deployed and later recovered by
a host platform, either tethered or autonomously,
while others can operate independently for long periods of time.
Persistent collection of environmental data at sea is
critical for global climate analysis and forecasting, and
understanding the ocean environment, which is