The Indian Ocean’s Agulhas Current is becoming wider rather than stronger, according to a new study by University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science researchers.
The findings have important implications for global climate change. The study suggests that intensifying winds in the region may be increasing the turbulence of the current, rather than increasing its flow rate.
One of the strongest currents in the world, the Agulhas Current flows along the east coast of South Africa, sending warm, salty water away from the tropics toward the poles. The Agulhas, which is hundreds of kilometers long and over 2,000-meters deep, transports large amounts of ocean heat and is considered to have an influence not only on the regional climate of Africa, but on global climate as part of the ocean’s global overturning circulation.
Boundary Current Changes
Lead author Lisa Beal, a UM Rosenstiel School professor of ocean sciences, said:
Using measurements collected during three scientific cruises to the Agulhas Current, the Indian Ocean’s version of the Gulf Stream, researchers estimated the long-term transport of the current leveraging 22 years of satellite data. They found the Agulhas Current has broadened, not strengthened, since the early 1990s, due to more turbulence from increased eddying and meandering.
Study co-author Shane Elipot, a UM Rosenstiel School associate scientist, said:
Previous studies have suggested that accelerated warming rates observed over western boundary current regions, together with ongoing strengthening and expansion of the global wind systems predicted by climate models relate to an intensification and pole-ward shift of western boundary currents as a result of man-made climate change.
Image: Cameron Kirby