Measuring a Whisper | Seeking Salt Fingers in the Tropical Atlantic

The #SaltyStaircases expedition took place 300 miles east of Barbados. In the northwestern equatorial Atlantic, the water column is highly stratified, with warm, salty water sitting atop cooler, fresher, nutrient-rich waters carried northward from the Antarctic by the Atlantic Meridional Overturning Circulation, or AMOC. These conditions make this region a hotspot for salt finger mixing, a fine-scale process in which heat and salt are exchanged across density gradients. Warm, salty water sinks into rising cold, nutrient-rich waters, creating a beautiful, swirling motion. Scientists suspect that these salt fingers transport essential nutrients for plankton growth, fueling ecosystem productivity and potentially influencing carbon export to deeper waters. Drs. Joseph Gradone and Corday Selden of Rutgers University, U.S., led an international team on an expedition to collect key data on salt fingers. Dr. Gradone likens their quest to measuring a whisper because these processes are so small, yet they play a pivotal role in a larger system we all depend on.