An ambitious idea spawned more than 20 years ago to develop a new way to watch the world change has come to fruition.
TheGlobal Drifter Program (GDP), largely led by Scripps Institution ofOceanography at the University of California, San Diego, and ScrippsDistinguished Professor Peter Niiler, will meet its lofty goal ofblanketing the globe on Sept. 18 when the program's 1,250th instrumentis dropped in the ocean off Halifax, Nova Scotia, Canada.
GDPbuoys, also called drifters, are designed to travel the oceans takingmeasurements of sea surface temperatures, ocean currents, air pressureand other parameters. By linking and disseminating the informationrelayed from each of these instruments in a global network, scientistsand others have been able to produce new details about the world'socean processes, key information for weather and climate forecastingand important calibrations of satellite readings.
"When the GDPdrifter data is combined with satellite measurements we can now obtaina complete, accurate map of the sea surface temperature of the worldtwice per week," said Niiler, a scientist in the Physical OceanographyResearch Division at Scripps. "These 'weather maps' of the oceansurface will tell us how Earth is warming up and where it is warmingmore than in other places. These combined data also give us an accuratepicture of the changing currents and patterns of ocean circulation."
TheGDP is a component of the National Oceanic and AtmosphericAdministration's (NOAA) Global Ocean Observing System and GlobalClimate Observing System.
According to Niiler, more than 250research papers have been published with new findings derived throughGDP circulation measurements. Many more have used its sea temperaturemeasurements. Topics have ranged from El Niños and La Niñas to globalclimate change.
Niiler believes the impact of GDP informationwill continue to grow because of the distinct characteristics displayedin current systems off coasts around the world. Analyzing the strongestnorth-south current system in the world, the Agulhas Current off theeastern coast of South Africa, tells a much different story thanstudying the California Current, the north-south circulation of thenorth Pacific Ocean that travels just off California's waters.
"TheGDP observations are of great interest to people all over the world,"said Niiler. "If you want to know what's happening in your backyard, oryou want to know what's happening on a global basis, these data willassist you."
When Niiler called a meeting of scientists inBoulder, Colo., in 1982, surface temperature readings and circulationpatterns were a mystery in large regions of the world, especially inthe Southern Ocean.
"A large part of the world simply could notbe sampled," said Niiler, "because most of the world's ships don't gothere. We needed a new way."
Niiler and his colleagues resolvedthat such gaps could only be filled with a completely new system ofobserving the entire Earth's oceans. They also decided that thismission could only be accomplished with the development of new oceaninstruments.
With long-term support from Scripps, Niiler and hiscolleagues began to work with engineers in designing and developinglow-cost, rugged drifters that measure currents with high accuracy andrelay their sensor information through existing satellitecommunications systems. Scripps and Niiler eventually led the design,manufacture, deployment and research analysis of the program. YetScripps scientists could not do it all alone, Niiler stresses, andnational and international partners played a significant role in theprogram's development through organizations that include NOAA'sAtlantic Oceanographic and Meteorological Laboratory, variousmeteorological groups, oceanographers from 20 countries and nearly allUnited States government research funding agencies. In the future, NOAAwill provide about 80 percent of the drifters to maintain the array.
Althoughthe GDP has met its goal of populating the global ocean with 1,250drifters, the array of instruments has become so valuable to scienceand other applications that the network will continue to grow.Challenges associated with drifter deployments in areas rarely visitedby ships will be addressed by increasing future deployments by air.Drifters are now deployed by the United States Air Force's "HurricaneHunter Squadron" in front of hurricanes to obtain data on hurricanestrength and size.
New ways of using the drifters as platformsfor environmental sensors also are being explored, includingmeasurements for rain, biochemical concentrations and surfaceconductivity.
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