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The Global Drifter Program (GDP) (formerly known as the Surface Velocity Program (SVP)) was conceived by Prof. Peter Niiler, with the objective of collecting measurements of surface
SVP project drifter deployments began in 1979; the design continued to develop until reaching its current form in 1992.Lumpkin, R. and M. Pazos, 2006: Measuring surface currents with Surface Velocity Program drifters: the instrument, its data, and some recent results. Chapter two of Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics (LAPCOD) ed. A. Griffa, A. D. Kirwan, A. J. Mariano, T. Ozgokmen, and T. Rossby. Each drifter consists of a spherical surface buoy tethered to a weighted nylon drogue that allows it to track the horizontal motion of water at a depth of 15 meters. If the drogue breaks off, the wind pushes the surface buoy through the water, creating erroneous current observations. A tether strain gauge has been added to monitor tension of the buoy-drogue connection to resolve this issue. The original drifters are heavy, bulky (40 cm diameter), and expensive relative to the newer "mini" drifters that are smaller, (30.5 cm diameter) cheaper, and lighter because the hull contains fewer batteries. The surface float contains alkaline batteries, a satellite transmitter, a thermistor for sub-skin sea surface temperature, and sometimes other instruments that measure pressure, wind speed and direction, or salinity. 
The drifters are deployed from research vessels, volunteer ships, and through air deployment. They typically transmit their data hourly and had an average lifetime of ~485 days in 2001. Presently, enough data is gathered to observe currents at a horizontal resolution of one degree (~100 km). Single drifters can b
tracked
with the name of the drifter.
GDP website
. The Lagrangian Drifter Laboratory at the
The Global Drifter Program (GDP) (formerly known as the Surface Velocity Program (SVP)) was conceived by Prof. Peter Niiler, with the objective of collecting measurements of surface ocean currents
An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours ...
, sea surface temperature and sea-level atmospheric pressure using drifters. It is the principal component of the Global Surface Drifting Buoy Array, a branch of NOAA's Global Ocean Observations and a scientific project of the Data Buoy Cooperation Panel (DBCP). The project originated in February 1979 as part of the TOGA/Equatorial Pacific Ocean Circulation Experiment (EPOCS) and the first large-scale deployment of drifters was in 1988 with the goal of mapping the tropical Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
's surface circulation. The current goal of the project is to use 1250 satellite-tracked surface drifting buoys to make accurate and globally dense in-situ observations of mixed layer currents, sea surface temperature
Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
, atmospheric pressure
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...
, wind
Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...
s and salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
, and to create a system to process the data. Horizontal transports in the oceanic mixed layer measured by the GDP are relevant to biological
Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, origin, evolution, and distribution of ...
and chemical processes as well as physical ones.Grodsky, Semyon A., Rick Lumpkin, and James A. Carton. "Spurious trends in global surface drifter currents." ''Geophysical Research Letters'' 38.10 (2011).
Drifters
SVP project drifter deployments began in 1979; the design continued to develop until reaching its current form in 1992.Lumpkin, R. and M. Pazos, 2006: Measuring surface currents with Surface Velocity Program drifters: the instrument, its data, and some recent results. Chapter two of Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics (LAPCOD) ed. A. Griffa, A. D. Kirwan, A. J. Mariano, T. Ozgokmen, and T. Rossby. Each drifter consists of a spherical surface buoy tethered to a weighted nylon drogue that allows it to track the horizontal motion of water at a depth of 15 meters. If the drogue breaks off, the wind pushes the surface buoy through the water, creating erroneous current observations. A tether strain gauge has been added to monitor tension of the buoy-drogue connection to resolve this issue. The original drifters are heavy, bulky (40 cm diameter), and expensive relative to the newer "mini" drifters that are smaller, (30.5 cm diameter) cheaper, and lighter because the hull contains fewer batteries. The surface float contains alkaline batteries, a satellite transmitter, a thermistor for sub-skin sea surface temperature, and sometimes other instruments that measure pressure, wind speed and direction, or salinity.
The drifters are deployed from research vessels, volunteer ships, and through air deployment. They typically transmit their data hourly and had an average lifetime of ~485 days in 2001. Presently, enough data is gathered to observe currents at a horizontal resolution of one degree (~100 km). Single drifters can btracked
with the name of the drifter.
Applications
The data from the GDP have been used byoceanographers
Oceanography (), also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its Physical oceanography, physics, Chemical oceanography, chemistry, Biological oceanography, biology, a ...
to derive maps of lateral diffusivity and Lagrangian length- and time-scales across the Pacific. Other uses include studies of plastic accumulation the ocean, and climatological
Climatology (from Greek , ''klima'', "slope"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. Climate concerns the atmospheri ...
models that simulate equatorial ocean currents, as well as many others.
Organization and collaborators
The GDP consists of three components. The component at NOAA'sAtlantic Oceanographic and Meteorological Laboratory
The Atlantic Oceanographic and Meteorological Laboratory (AOML), a federal research laboratory, is part of the National Oceanic and Atmospheric Administration's (NOAA) Office of Oceanic and Atmospheric Research (OAR), located in Miami in the Unit ...
(AOML) manages deployments, processes and archives the data, maintains META files describing each drifter deployed, develops and distributes data-based products, and updates thGDP website
. The Lagrangian Drifter Laboratory at the
Scripps Institution of Oceanography
Scripps Institution of Oceanography (SIO) is the center for oceanography and Earth science at the University of California, San Diego. Its main campus is located in La Jolla, with additional facilities in Point Loma.
Founded in 1903 and incorpo ...
(SIO) leads the engineering aspects of the Lagrangian drifter technology, improves the existing designs, develops new drifters, manages the real-time data stream, including posting the drifter data to the Global Telecommunication System, supervises the industry, purchases and fabricates most drifters, and develops enhanced data sets. The third component is the manufacturers in private industry, who build drifters according to specifications. The GDP collaborates with partners from numerous countries including Argentina, Australia, Brazil, Canada, France, India, Italy, Republic of Korea, Mexico, New Zealand, South Africa, Spain, United Kingdom, and the United States.
References
{{Reflist Oceanography