Ocean Snapshot

A group gathered on the stern of R/V Chain during a thermistor chain deployment in 1958. Although this sensor array is often called a “chain,” it is actually a flexible cable outfitted with thermistors to measure temperature, as well as sensors to record salinity, fluorescence and optical sensors. A weight or depressor plate holds the end down while the cable is towed behind the ship, allowing the thermistors to generate a continuous vertical “snapshot” of the water column’s temperature as the ship steams along. Thermistor chains are still widely used today and are also used on mooring arrays.(Photo courtesy of Woods Hole Oceanographic Institution Archives)