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Argo was designed specifically to exploit the complementary
relationship between satellite measurements of sea surface height
(SSH) and subsurface profile measurements of temperature, salin-
ity and velocity. Indeed, the name Argo was chosen to
underline the float programme’s synergy with the
Jason satellite altimeter. On seasonal and longer
timescales, SSH changes measured by Jason are largely
due to temperature and salinity changes in the water
column, measured by Argo. SSH during the El Niño
event of late 2006 (centimetres difference from the
2004-2006 mean) measured by Jason and the part of
SSH due to ocean temperature and salinity changes
measured by Argo show a striking similarity, demon-
strating that these key observing systems are operating
in tandem to capture large-scale phenomena.
Differences between the two sets of measurements can
be exploited to determine previously inaccessible
features of ocean change.
The Argo array, while still growing in coverage and
capabilities, is moving into a pre-operational phase that
requires the array to be sustained for a ten-year period,
while its value in various applications is assessed. This
will allow time for the operational agencies and the
scientific researchers of the world to learn how to use
the new dataset, understand its synergy with other
observing system elements and its role in both new and
existing applications. The societal need for climate
observations to monitor the state of the planet and give
early warning of significant change creates a responsi-
bility to implement and sustain measurement systems
that are matched to the global scope of the climate
problem.
Argo and Jason offer complementary views of the oceans
Sea surface height anomaly in November 2006 (cm, relative to a three-year mean 2004-2006) estimated from Argo profile data (a) and from satellite
altimetry (b). High values in the eastern equatorial Pacific indicate El Niño conditions
Source: Dean Roemmich
Argo
1960
1970
1980
1990
2000
6.20
6.22
6.24
6.26
6.28
6.30
Global, annual mean, 0-200m
Historical data
Historical (pre-Argo) data and Argo data showing the global annual mean
ocean temperature at 0-2,000 metres
Global annual mean ocean temperature, 0-2,000 metres
Source: Dean Roemmich
GEOSS C
OMPONENTS
– O
BSERVING
S
YSTEMS