Study reveals acceleration in Pacific upper-ocean circulation over past 30 years, impacting global weather patterns

The research team, led by Franz Philip Tuchen, a postdoctoral scientist at the University of Miami Rosenstiel School's NOAA Cooperative Institute for Marine and Atmospheric Studies (CIMAS), in collaboration with NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML), synthesized thirty years of long-term ocean and atmosphere observations from satellites, mooring buoys, and ocean surface drifters. By integrating the reanalysis of wind data and satellite altimetry into a high-resolution, gridded time series of near-surface ocean currents, this study presents a new and comprehensive view to date of the changes in the Pacific upper-ocean circulation.

The research findings indicate that stronger winds across the equatorial Pacific have caused a notable acceleration of westward near-surface currents by approximately 20 percent in the central equatorial Pacific. Poleward currents north and south of the equator have also accelerated, with increases of 60 percent and 20 percent, respectively.

"The equatorial thermocline -- a critical ocean layer for El Niño-Southern Oscillation (ENSO) dynamics -- has steepened significantly," said Tuchen. "This steepening trend could reduce ENSO amplitude in the eastern Pacific and favor more frequent central Pacific El Niño events, potentially altering regional and global climate patterns associated with ENSO."

The researchers indicate the study offers a benchmark for climate models, which have had limited success to accurately represent Pacific circulation and sea surface temperature trends. The researchers suggest the findings could help improve the predictability of ENSO events and related weather patterns, especially for regions like the United States, which experience significant climate variability from ENSO-driven changes.

Funding for this study was provided by NOAA's Global Ocean Monitoring and Observing (GOMO) programs, including the Global Tropical Moored Buoy Array (GTMBA), the Global Drifter Program (GDP), and the Tropical Atmosphere Ocean (TAO) program.