Drifter (floating device)
A drifter (also float) is an oceanographic device floating on the surface or at a given water depth to investigate ocean currents and other parameters like temperature or salinity. They are also called Lagrangian drifters since they follow the flow in a Lagrangian manner. The depth of drifter is defined by its neutral buoyancy. The device stops sinking when its buoyancy force is in equilibrium with its gravitational force.
The major component of a drifter are hollow bodies that ensure flotation, underwater-sails to catch water currents, instruments (e.g., data collecting instruments, transmitters to transmit the collected data, and GPS devices), and waterproof containers for instruments. Drifters are a hi-tech evolution of the ocean current analysis by means of drift bottles, which in their turn evolved from simple collection of data about messages in a bottle.
Drifters provide real-time information about ocean circulation. The data is a valuable input for weather forecasts as meteorological satellites can at maximum measure the sea surface temperature or the surface roughness of the world oceans, but it is not possible to look into the water column. Data from inside the ocean is helpful for hurricane prediction as well.
- ALACE (Autonomous Lagrange Circulation Explorer)
- Argo float
- PALACE (Profiling Autonomous Lagrange Circulation Explorer)
- Davis drifter
- Polar Profiling Float
- SOFAR float
- Swallow float
- Ice rafting, another means to investigate ocean circulation
- Swallow float
- Pearn P. Niiler – responsible for many developments in drifter technology and establishment of the Global Drifter Program
- Friendly Floatees