Development of the
Tropical Atmosphere Ocean (TAO) array was motivated by
the 1982-1983 El Nino event, the strongest of the
century up to that time, which was neither predicted
nor detected until nearly at its peak. The event
highlighted the need for real-time data from the
tropical Pacific for both monitoring, prediction, and
improved understanding of El Nino. As a result, with
support from NOAA's Equatorial Pacific Ocean Climate
Studies (EPOCS) program, PMEL began development of the
ATLAS (Autonomous Temperature Line Acquisition System)
mooring. This low-cost deep ocean mooring was designed
to measure surface meteorological and subsurface
oceanic parameters, and to transmit all data to shore
in real-time via satellite relay. The mooring was also
designed to last one year in the water before needing
to be recovered for maintenance.
Under the
direction of PMEL scientist Stan Hayes, prototype ATLAS
were field tested in early 1984, and a modest scale
array was deployed along 110W in late 1984. Additional
ATLAS deployments were made beginning in 1985 at the
start of the 10-year (1985-94) international Tropical
Ocean Global Atmosphere (TOGA) program. The array,
named the Tropical Atmosphere Ocean (TAO) array, grew
slowly during the first half of TOGA as the proof of
concept for a sustained buoy observing system was
evaluated. Initial successes led to a rapid expansion
of the array during the second half of TOGA with the
widespread support of the climate community.
The full array of nearly 70 moorings was not
completed until the final month of TOGA (Dec 1994).
During the 10 years in which the array was under
development, over 400 buoys were deployed on 83
cruises, using 17 different ships from 6 different
countries. Accomplishing this feat required a
multi-national partnership of institutions in the US,
Japan, France, Taiwan, and Korea.
After TOGA ended in 1994, the TAO array
continued under sponsorship of the international
Climate Variability and Predictability (CLIVAR)
program, the Global Ocean Observing System (GOOS), and
the Global Climate Observing System (GCOS). In 1996,
the NOAA Ship KA'IMIMOANA was commissioned to service
the TAO array east of 165E. In 1997, the US Congress
authorized long term sustained support of the TAO array
as part of an operational El Nino/Southern Oscillation
(ENSO) observing system. On 1 January 2000, the TAO
array officially became the TAO/TRITON array, with
sites west of 165E occupied by TRITON (Triangle Trans
Ocean Buoy Network) buoys maintained by the Japan
Agency for Marine-Earth Science and Technology
(JAMSTEC).
The operationally supported measurements of
the TAO/TRITON array consist of winds, sea surface
temperature, relative humidity, air temperature, and
subsurface temperature at 10 depths in the upper 500 m.
Five moorings along the equator also measure ocean
velocity. Additional moorings and/or enhancements to
the basic measurement suite are often incorporated to
the operational array in support of research studies to
understand specific physical processes not well
measured by the existing network. Other measurements
may be made for satellite or numerical model validation
purposes. These research efforts are usually of limited
duration and/or geographical scope, and done in
collaboration with other institutions in the US and
abroad.
To meet the demands of both operational and
research measurements in the TAO array, an
engineering redesign
of the ATLAS was initiated in 1994 to update it with
greater measurement capabilities, improved ocean
temperature sensor accuracies, and more modular
construction. The current generation ATLAS now has the
capability to measure and transmit in real-time
salinity, rainrate, long and shortwave radiation,
barometric pressure, and ocean velocity. These
measurements are made at selected sites to meet the
needs of specialized research experiments.
In 2005, a new
milestone was achieved when the operational U.S. role
in the TAO array began to transfer from PMEL to NOAA's
National Data Buoy Center (NDBC). NDBC has well over 30
years of experience in maintaining operational buoy
networks. The transition concentrates first on data
management functions such as this TAO web site and
quality control. The next phases will consist of the
development, testing and eventual fielding of the next
generation of instruments and data logging and
communications electronics by NDBC. PMEL will continue
to have a lead R&D role for tropical moored buoy
technology, continuing its strong tradition of science
innovation in the marine sensing field.
The TAO/TRITON array is currently supported by
the US (NOAA), Japan (JAMSTEC), and France (IRD).
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