THE ARGO PROJECT: GLOBAL OCEAN OBSERVATIONS FOR UNDERSTANDING AND PREDICTION OF CLIMATE VARIABILITY
Link to NOAA Strategic Plan: NOAA's Mission Goal 2: Understand Climate Variability and Change to Enhance Society's Ability to Plan and Respond;
Goal 3: Serve Society's Needs for Weather and Water Information
RESEARCH OBJECTIVES AND SPECIFIC PLANS TO ACHIEVE THEM
Argo is an international collaboration providing a global array of profiling CTD floats for a broad range of operational and scientific applications (http://www.argo.ucsd.edu). The Argo array, now including about 2850 active floats (Fig. 1), is providing unprecedented real-time views of the evolving physical state of the ocean. These measurements reveal the physical processes that balance the large-scale mass, heat, and freshwater budgets of the ocean on basin-to-global scale. Argo is a large initiative for oceanography, merging research and operational objectives to provide a uniquely valuable global dataset for climate science, ocean state estimation, seasonal-to-decadal forecasting, and other applications. All Argo data are freely available in near-real-time.
SIO plays a number of key roles within U.S. and international Argo. The U.S. provides 50% of the international array, including instrumentation development, float production and deployment, communications and data management, and scientific analyses to demonstrate the value of Argo data. SIO produces and deploys one-fourth of the U.S. floats, carries out float technology development, participates in delayed-mode quality control, coordinates the U.S. Argo partnership, and provides leadership for international Argo (Argo Director and Argo Steering Team co-chairman).
RESEARCH ACCOMPLISHMENTS
During the past year (07/2006 – 06/2007), 113 SIO Argo floats were built, shipped and deployed. All but 3 of these instruments are presently active. An additional 31 floats were onboard R/V Kaharoa on 30 June 2007 and have since been deployed.
The total number of active SIO Argo floats is now 415 (Fig. 1). For all active floats, profile and engineering data are carefully monitored to identify any technical problems with the instrument or sensor. Technology development continues to focus on further improvements in reliability and capability of profiling floats. A complete redesign of the SIO SOLO float is near completion, with prototype instruments to be deployed later this year. The new SOLO design will provide greater buoyancy adjustment and more robust operation. Float technology aspects of SIO Argo are overseen by R. Davis.
Scientific quality control of all SIO Argo profile data has been carried out by J. Gilson and M. Scanderbeg according to protocols set by the international Argo Data Management Team. All eligible delayed-mode profiles (i.e. > 12 months old) have been reviewed. SIO Argo data are available from either of the two Argo Global Data Assembly Centers.
D. Roemmich has been Chairman of the international Argo Steering Team since its inception in 1998. The AST, which is responsible for coordinating the international Argo partnership, met in March 2007 at the Intergovernmental Oceanographic Congress of UNESCO’s headquarters in Paris. The meeting report for AST-8 is available from http://www.argo.ucsd.edu/FrMeeting_reports.html. J. Gould has transitioned from the role of Argo Director to part-time Consultant, supporting a variety of AST activities, with assistance from M. Scanderbeg. A major effort this year was in staging the two-day Argo/GODAE Special Session at the International Union of Geodesy and Geophysics General Assembly.
Since most SIO Argo floats are in the tropical and South Pacific, scientific analysis efforts are focused there and on global research (e.g. Fig. 2). A major effort has been construction of a gridded Argo dataset for the period 2004–2007. Monthly fields were produced by objective mapping on a 1o x 1o grid from 62oS to 65oN. The gridded Argo dataset has been used both to describe the mean and annual variability of temperature, salinity, and dynamic height as well as to characterize decadal variability by comparison to previous climatological datasets.
Fig. 1
As of July 2007, there are 2850 active profiling floats in the global Argo array (black and red dots), including 415 built and deployed by SIO (red dots). The Argo array is near completion. Each float collects a profile of temperature and salinity versus depth every 10 days, and all data are made publicly available via the internet within about 24 hours.
Fig. 2
(Top) Mean dynamic height of the sea surface (dynamic cm) relative to 2000 m from Argo, 2004–2007. (Bottom) Argo minus the World Ocean Atlas 2001 climatology of dynamic height of the sea surface relative to 2000 m. Note the height gain of about 10 dynamic cm over all of the Southern Ocean, due to strong multi-decadal warming at high southern latitudes.
