Argo

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Argo April 2004 The status of the Argo project
and of the US contribution to it.
What is Argo trying to do How is it doing
it? What have we achieved so far? What has
happened since last year? What impact is Argo
having? What are the targets and challenges
for the coming years?

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What is Argo trying to do?

• Collect a novel global temperature/salinity data
  set. ( Restricted to ice-free areas, deeper than
  ca2000m)
• Make data available in real-time (24hrs)
• Achieve delayed-mode data quality approaching
  that of research ship observations
• Use with other in-situ and satellite data for
  ocean state estimation and ocean forecasting
  (GODAE).
• Document ocean heat and fresh water storage and
  large scale transport (CLIVAR)

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How is it trying to achieve this?

• Array of 3000 autonomous profiling floats.
  Derived from floats used in WOCE (1990-1998).

Collaboration of many countries. All
subscribe to global objectives and freedom of
data access.
Start array in 1999. Completion estimated
by end 2006.
Its primary impetus comes from the requirements
of two projects - GODAE - Global Ocean Data
Assimilation - CLIVAR - Climate Variability and
Predictability
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Float technologies
Three models SOLO - designed and
constructed by SIO (USA) APEX - designed and
marketed by WRC (USA) PROVOR - designed and
marketed by Martec (France)
Two CTD sensor suites FSI (USA)
SeaBird (USA)
Prototypes being developed Ninja (Japan -
JAMSTEC) COPEX (China - IOT) New Martec -
1002000m cycles, no ballasting
Overall US technologies dominate Argo
85 of global array 100 of sensors
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How are they deployed?
Research ships Rarely visited area
Technical support available Ancillary data
collection - Few such ships Commercial
vessels Long tracks - Mostly N hemisphere -
Need to provide tech support - Vessel wont
stop Aircraft (C-130) Dedicated mission
Remote area coverage - Logistics
(certification) - Higher failure rate?
SOLO float deployments
NZ RV Kaharoa
Logistical challenge - deploy 800 floats per
year
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The Argo real time data system
AOML for US data
US GODAE Coriolis
WDC-A US NODC
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What have we achieved so far?
1120 floats delivering data now -770 last year
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How much data is being delivered?
5700 per month ?
Number of profiles being delivered in real time
each month (Data from AOML, Miami)
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How are the data being used?
Over 10 operational ocean analysis and
forecast centers are using Argo data. Key factors
benefits cited are - Depth penetration (gt
XBTs) Improved data quality Availability
of salinity No seasonality in distribution
Uniform spatial coverage Global coverage
Wide range of climate science (Nov 2003
Workshop) Air-sea interaction under tropical
cyclones ENSO forecasts other seasonal
forecasts Indian monsoon Decadal and
anthropogenic change
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Some Argo-based pre-operational products
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Metéo France. Salinity at 1000m byassimilating
Argo data.
UK Met Office salinity at 300m from operational
model. Difference from Levitus Top. Old
model. Bottom New model with salinity
assimilated
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Remaining challenges
Complete the global array (Sustain funding,
address
N hemisphere bias) Sustain and improve
float reliability
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Argo float failure rates
These are based onan exponential (e.g. 0.002 per
cycle) failure rate and are amore meaningful
measure than floatperformance being 100 until
it fails. Statistics are for two large batches
of recent model floats and a small batch of an
earlier model
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Remaining challenges
Complete the global array (Sustain funding,
address
N hemisphere bias) Sustain and improve
float reliability
Improve technology (communications, sensors)
Delayed-mode quality control Implement
system just agreed Clear backlog Improve
and update T/S climatologies Regional data
centers Evaluate data Work closely with
GODAE Dialogue with users
Provide appropriate international
infrastructure Entrain new countries - Float
providers - Deployment help - EEZ
access Outreach - Web sites, brochure,
education (SEREAD)
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The present challenge in context From The Argo
Prospectus (N. Smith, 1998)
As with the sampling strategy, there are
presently uncertainties concerning the technical
development and cost of the floats, concerning
telemetry, and relating to deployment.  It would
be unwise to portray these as solved issues, but
it would be equally a poor strategy to delay
given the already demonstrated capabilities of
the instrument and the compelling scientific and
societal justifications for the array. In the
following we try to give cost and capability
estimates for the present, near-future (Year
2000) and five years hence when presently
developing technology should be ready for
implementation and GODAE is beginning its
intensive, experiment phase.
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