Large-scale ocean circulation is critical to our planet’s health and climate. In this process, seawater near the poles cools and sinks into the deep ocean, carrying dissolved carbon and nutrients with it. Later, that cold water gets pushed back up to the surface elsewhere, where it warms, and the cycle repeats. Although the theory behind this circulation has been around for decades, it’s been difficult to observe the rise, or upwelling, of water from the depths. But a recent study used a fluorescent, non-toxic dye to measure upwelling directly.
Researchers deployed 200 liters of dye just above the floor of a marine canyon near Ireland, then monitored the dye’s movement for several days at a depth of 2200. They found that turbulence along the slope of the canyon drove upwelling at speeds of about 100 meters per day, much faster than global rates. The authors suggest that this kind of topographically-enhanced upwelling could be a major factor in setting overall ocean circulation. (Image credit: visualization – NASA, ship – S. Nguyen; research credit: B. Wynne-Cattanach et al.; via Physics World)
