How does ocean circulation work? New research that looks into the mechanism of ocean circulation could impact our current understanding of climate change
Led by Scripps postdoctoral fellow Bethan Wynne-Cattanach, the international team conducted measurements along the slope of a submarine canyon in the Atlantic Ocean.
What they discovered challenges long-held theories about how cold, deep water moves within the ocean.
Challenging the traditional model of ocean circulation
The study’s findings highlight a phenomenon called turbulent mixing-driven upwelling. This process, observed for the first time directly, involves cold, dense water rising rapidly from the deep ocean to the surface along steep underwater slopes.
The rate of upwelling measured was extremely high, more than 10,000 times faster than previously estimated by renowned oceanographer Walter Munk in the 1960s.
The traditional model of ocean circulation, often referred to as the conveyor belt, relies on the movement of cold, dense water sinking near the poles and resurfacing in other regions. However, the exact mechanisms driving the return of this deep water to the surface, known as meridional overturning circulation (MOC), have been elusive until now.
Turbulent upwelling process
The team’s experiments involved using a non-toxic, fluorescent dye deployed in a deep undersea canyon off the coast of Ireland. By tracking the movement of the dye, researchers were able to directly observe the turbulent upwelling process. This method provided high-resolution data showing how ocean currents interact with the steep topography of the canyon’s walls.
“We’ve observed upwelling that’s never been directly measured before,” said Wynne-Cattanach. “The rate of that upwelling is also really fast, which, along with measurements of downwelling elsewhere in the oceans, suggests there are hotspots of upwelling.”
Improved understanding of turbulent mixing-driven upwelling could lead to more accurate climate simulations and better predictions of future climate change impacts. It shows the importance of integrating complex ocean processes into global climate models.
“This work is the first step to adding in missing ocean physics to our climate models that will ultimately improve the ability of those models to predict climate change,” Alford emphasised. “We need to be doing more high-tech, high-resolution experiments like this one in key parts of the ocean to better understand the physical processes.”
