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.
Utilize near real-time data on flow, sea surface temperature, wind
and ocean color to augment your current research or future investigation
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.
- Drifter data can be used to verify or ground truth data from
satellites, such as sea surface temperatures or ocean color
- 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
- Industries that rely on ships for transport or have extensive
operations at sea, use drifter tracks to better understand current