Objective: Our objective is to maintain a global array of Argos-tracked Lagrangian drifters to meet the need for an accurate and globally dense set of in situ observations of sea-surface temperature (SST) and surface circulation to support short-term (seasonal-to-interannual) climate predictions as well as climate research and monitoring.
Rationale: The project is based on the need for high-quality in situ measurements of SST for initializing short-term climate prediction models as well as for producing global SST maps upon which the assessment of the utility of the models depends. The surface velocity data provide a valuable independent constraint on the veracity of the ocean component of the climate prediction models.
Method: The Global Drifter Center (GDC) at AOML is responsible for scheduling the deployments of a total of 450 Global Lagrangian Drifters per year in all of the world's ocean basins and maintaining the Global Drifter Array. This entails contacting research vessels and Volunteer Observing Ships, placing drifters on ships and teaching correct deployment methods. Similar arrangements for air deployments are also made in order to seed some very remote areas. The GDC furthermore coordinates the international Surface Velocity Program which is co-sponsored by the World Ocean Circulation Experiment (WOCE) and the Climate Variability and Predictability (CLIVAR) program of the World Climate Research Programme and acts as the liaison between SVP members and the WOCE and CLIVAR project offices. Finally, the GDC is responsible for monitoring the survivability of the drifter arrays, maintain a comprehensive metadata file and publish reports about the global array in meeting reports and popular scientific journals.
Accomplishment: The transition of the GDC from the Scripps Institution of Oceanography (SIO) to AOML, which was begun in October 1994 has been completed with excellent results. The planned six month overlap between SIO and AOML was abbreviated considerably. Also, rather than simply maintaining the existing array, new arrays were installed in three areas: the Indian, Southern and northeast Pacific Oceans during the transition period. World-wide, over seven hundred drifters were being monitored (figure) by the GDC on March 30, 1995. Drifters are being placed at a rate of more than one per day, and that pace is expected to increase soon as several large deployments begin. More than 350 drifters were deployed during fiscal year 1995, and over 50 are presently shipped and poised for deployment.

The past year saw the first large-scale deployments of barometer drifters in the Southern Ocean, South Atlantic Ocean and the northwest Pacific Ocean. These instruments have required careful monitoring to ensure that they are operating in good condition and that the data, which are used in numerical weather predictions in near-real time by meteorological centers throughout the world, are being put to best advantage.

There were several instances during the year in which flaws or manufacturing defects arose, requiring that 154 drifters be tested before deployment. In addition to maintaining the drifter array, several initiatives have been undertaken to support the growth and quality of the Global Drifter Array: (a) we have begun a database of BUOY-QC drifter quality control messages which has been used to create the first evaluation report on barometer drifter success, (b) we began procurement of four Global Position System (GPS) drifters to test the utility of GPS, (c) NOAA's Oceanographic Data Distribution System software has been installed to monitor the dissemination of barometer drifter data on the Global Telecommunications System.

Key reference:

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