Educators

Use data from ocean drifting buoys to integrate ocean science into your classroom science and math instruction. Enhance your lessons with suggested educational activities and curriculum materials developed and tested by teachers, or you can use only the data, background information and reference images.

Scientists

Utilize near real-time data on flow, sea surface temperature, wind and ocean color to augment your current research or future investigation plans.

Background

Though the oceans cover over 70% of the Earth's surface, we have explored only a small percentage of their vast expanse and are just beginning to grasp the complexities of the global ocean system. In 1998, the global impacts of the ocean have been dramatically illustrated, as the effects of one of the largest and most costly El Niņo events continue to be felt worldwide.

Ocean currents play an extremely important role in the global transfer of water, heat, organisms, nutrients, potential pollutants, and sediments. From the time explorers set sail to discover new lands to the present day when deep-sea submersibles venture deep into the oceans depths, knowledge of how water flows within the sea has been sought. Today we use satellite and computer technology, combined with years of experience to investigate how water moves within the ocean.

In one of the earliest attempts to study ocean currents, scientists aboard the R.M.S. Challenger used a float designed specifically to drift passively with the flow of water. The 1872 Challenger Expedition was the first sea voyage whose sole purpose was to study the world's oceans.

Of course in those days, the path of the drifter had to be tracked by an accompanying boat, making this a time-consuming and spatially-limited activity. Using modern technology, today's oceanographers have developed an ingenious way to use the same principles, but with much greater accuracy and spatial coverage.

Drifter Design and Deployment

When using drifters to track an ocean current, one of the major obstacles is wind. Unless the drifter is designed correctly, it may be blown along by the wind, rather than being transported within an ocean current. It is extremely important to use a float with relatively little surface area exposed to the wind, and a subsurface sail which captures flow at depth and causes the drifter to move with the average flow of water. A design which has been successfully used throughout the world is sometimes called the "holey sock" drogue.

Drifters are typically deployed into the sea from a ship. Sometimes drifters are deployed from an airplane. Once floating within the ocean's surface water, a transmitter on the drifter sends a signal to Earth orbitting satellites which then relay the drifter's position to a receiving station. The data are then sent to the data assembly center where they are processed and distributed. Drifters may also house sensors which measure other ocean properties such as surface temperature, wind, ocean color, pressure, or salinity, and these data can also be transmitted through the satellite link. A typical drifter will transmit data for approximately 1.5 years. The accuracy of ocean drifter positions averages approximately 500 m, a reasonable level of error considering the scale of the open ocean features the drifters are used to track.

How Drifter Data are Used

• Oceanographers use drifter data to track major ocean currents and eddies throughout the world.
  • Drifters in the Southwestern Caribbean
  • Currents in the Gulf of Mexico and Comparison with Sea Surface Height Data
  • NOPP Drifters in the Caribbean Sea and the Birth of the Gulf Stream

• Drifter data can be used to verify or ground truth data from satellites, such as sea surface temperatures or ocean color
  • The Living Ocean (The SeaWIFS Project)

• Data from drifters can be used to predict where pollutants, such as oil or sewage, would go if dumped or accidentally spilled into the sea.

• Scientists also use drifter data to build models of climate and weather patterns, such as El Niņo or hurricanes.

• Many organisms in the ocean drift along with ocean currents, especially the larvae or young of many marine species. Studies on the world's fisheries use drifter tracks to understand where organisms, such as the spiny lobsters in Florida, originate, and how they live.
  

• In the cold, northern waters where the Titanic sank, the United States Coast Guard patrols the seas mapping iceberg positions and using drifters to track their potential movement.

• Industries that rely on ships for transport or have extensive operations at sea, use drifter tracks to better understand current patterns.