For Boss, that starts by determining what is in the ocean and why it’s there. Using passive sensors that take advantage of the sun’s light as a source, and active optical sensors that produce their own light source, he quantifies particle concentration, composition and size distribution. Optical properties of suspension reveal changes in concentration of material in the water.
Boss is also beginning to study acoustical properties of the water column by measuring sound intensity scattered by particles at different frequencies.
“Acoustical and optical properties of material reflect on their size, composition and, to a lesser degree, on their shape and internal structure. Different wavelengths of light or frequencies of sound interact with the material differently, meaning they are sensitive differently to the properties of the particles,” says Boss.
Those properties were primarily measured by sensors on stationary buoys or aboard ships. Boss has pioneered the use of profiling floats designed to collect ocean temperature and salinity profiles to measure biogeochemical properties. The battery-powered devices drift with the currents, descending and ascending by taking in or releasing oil in an external bladder. At the surface, the float relays data via a satellite to users, as well as international databases.
“Oceanographers have collected a lot of data in the open ocean, but during spotty campaigns and on moorings lasting only a few years,” says Boss. “The floats allow you to have a persistent presence.”