RAFOS floats are designed to take measurements of temperature, salinity, and pressure in layers of ocean water at any depth.They are deployed using one of two methods. Some floats are attached to a small anchor and dropped over the side of a research vessel (left). They sink to the bottom and remain there, in a dormant state, until a preprogrammed time when they release the anchor and rise up to their target depth to start their drifting mission.
After completing their drifting mission, these floats release a second weight and rise to the sea surface, where they transmit all their stored data to orbiting satellites which then rebroadcast the information to ground stations (right).
Most floats however begin their drifting missions immediately after deployment from a research vessel or ship of opportunity (middle). At the end of their drifting mission, they also transmit the data they collected to satellites that relay the information to the scientist. (Illustration by Jayne Doucette, Woods Hole Oceanographic Institution)
WHOI physical oceanographer Amy Bower prepares a RAFOS float for launch from the research vessel Oceanus during a study of the Deep Western Boundary Current in 1995. (David Fisichella, Woods Hole Oceanographic Institution.)
Susan Lozier, professor of physical oceanography at Duke University (left) and Ana Rappold, a Duke graduate student at the time, prepare to launch an expendable bathythermograph, or XBT, on a 2003 cruise aboard the research vessel Oceanus. The XBT collects measurements of water temperatures at depths within the ocean. (Photo by Jaime Palter, Duke University )