Current Status of Argo
The broad-scale
global array of temperature/salinity profiling floats, known as Argo,
has already grown to be a
major component of the ocean observing
system. Argo is a standard to which other developing ocean observing systems can look to. For example,
Argo offers ideas on various topics such as how to collaborate internationally, how to develop a data
management system and how to change the way scientists think about collecting data. Deployments began
in 2000 and continue today at the rate of about 800 per year.
The latest picture of the
Argo array.
Additional maps displaying statistics about the Argo array, including its extensions into high latitudes and marginal seas,
bio-geochemical sensors, communication systems, float type, etc.,
can be found in the
map section on the Argo Information Centre website.
Brief History of Argo
The name Argo was chosen to emphasize
the strong complementary relationship of the global float
array with
the Jason
satellite altimeter mission. In Greek mythology Jason sailed in a ship called "Argo" to capture
the golden fleece.
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An Argo float being deployed from a research ship. |
Together the Argo and Jason data sets are assimilated into computer models developed by
GODAE OceanView
that will allow a test of our ability to forecast ocean climate.
For the first time, the physical state
of the upper ocean is being systematically measured and the data
assimilated in near real-time into computer models.
Argo builds on other upper-ocean ocean observing
networks,
extending their
coverage in space an time, their depth range and
accuracy, and enhancing them through the addition of
salinity and
velocity measurements. Argo is not confined to major shipping routes which can vary with season
as the other upper-ocean observing networks are. Instead, the global array of 3,000 floats will be distributed
roughly every 3 degrees (300km). Argo is the sole source of global subsurface datasets used in
all ocean data assimilation models and reanalyses.
Argo's Objectives
- It
will provide a quantitative description of the changing state of the
upper ocean and the patterns of ocean climate variability from months
to decades, including heat and
freshwater storage and transport.
- The
data will enhance the value of the Jason altimeter through measurement of subsurface temperature, salinity, and velocity,
with sufficient
coverage and resolution to permit interpretation of altimetric
sea surface height
variability.
- Argo data will be used for initializing ocean and
coupled ocean-atmosphere
forecast models, for data assimilation and for model testing.
- A primary focus of Argo is to
document seasonal to decadal climate variability and to aid
our
understanding of its predictability. A wide range of applications for high-quality global ocean analyses
is
anticipated.
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An Argo profile from the subtropical North Pacific
(20.25N 121.4W, May 15 2004). This shows interleaving in the
salinity data.
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Argo Design and Data
The design of the Argo network is
based on experience from the present observing system, on recent
knowledge of variability from the TOPEX/Poseidon altimeter, and on
the requirements for climate and
high-resolution ocean
models.
The array of ~3200 floats
provides 100,000 temperature/salinity (T/S) profiles and velocity measurements per year
distributed over the global oceans at an average 3-degree
spacing. Floats will cycle to
2000m depth devery 10 days, with 4-5 year lifetimes for individual instruments.
All data collected by Argo floats are
publically available in near real-time via the Global Data Assembly Centers (GDACs) in Brest, France and
Monterey, California after an automated
quality control (QC), and in scientifically quality controlled form, delayed mode data,
via the GDACs within one year of collection.
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