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The Global Drifter Center at NOAA's Atlantic Oceanographic and Meteorological
Laboratory maintains an array of drifting buoys worldwide. A strong international
community of cooperating oceanographers and meteorologists supplement the
u.s. contribution, and the present array contains over 600 buoys.
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The drifters all provide Sea Surface Temperature (SST) and ocean current
observations. Some also have barometric pressure, salinity, Global Positioning
System (GPS), ocean color and/or wind speed and wind direction sensors.
All the drifters have a drogue, centered at a depth of 15 meters, to eliminate
wind effects on the drifters and make them better current followers. Drifters
typically transmit for about 1.5 years, although some have lasted 5 years.
All drifters transmit data via Argos receivers aboard NOAA's two operational
Polar Orbiting Environmental Satellites (POES). Data is formatted by Argos
for global distribution to operational forecast offices and ocean/atmosphere
modeling centers by the Global Telecommunications System (GTS).
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Figure 1: Annual velocity estimates, drifters drogued at 15 meters. |
Over fifteen years of drifting buoy data have been processed by the Data
Assembly Center (DAC) at aoml, and more than 3,500 drifting buoys have been
deployed. The DAC/GDC maintains a web site at http://www.aoml.noaa.gov/phod/dac/.
Photos of drifters being deployed, and present drifter locations are
available at this site. Maps showing the average ocean currents and the
variability of those currents can also be found.
To encourage drifter deployments, oceanographers have added barometers
and wind sensors to the drifters. While this has helped to increase the
number of drifters in the ocean, it has also forced oceanographers to begin
data processing in real time. At present, the GDC web site continues to
operate at oceanographic time scales, relying upon Argos and GTS to distribute
the data to forecasters. As resources become available from meteorological
agencies, data products from atmospheric sensors will be displayed at our
web site.
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Figure 2: Status of global drifter array. |
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