Study Finds Faster Upper-Ocean Flow in the Pacific

A recent study has uncovered a notable increase in the upper-ocean circulation of the equatorial Pacific over the past 30 years. This acceleration is primarily driven by intensified atmospheric winds, resulting in stronger and shallower ocean currents. These changes could significantly influence regional and global climate patterns, including the dynamics of El Niño and La Niña events.

The research team, led by Franz Philip Tuchen from the University of Miami's Rosenstiel School in collaboration with NOAA's CIMAS, utilized a wealth of data from satellites, mooring buoys, and ocean surface drifters. Their work synthesizes three decades of oceanic and atmospheric observations, adding valuable insights to previous studies.

Published in the Journal of Geophysical Research: Oceans on October 31, 2024, the study is titled "Strengthening of the Equatorial Pacific Upper-Ocean Circulation Over the Past Three Decades." The researchers integrated reanalyzed wind data and satellite altimetry into a high-resolution time series to depict the changes in the Pacific's upper-ocean circulation more accurately.

Findings indicate that the stronger winds across the equatorial Pacific have led to a 20% acceleration of westward near-surface currents in the central equatorial region. Additionally, poleward currents north and south of the equator have also increased significantly, by 60% and 20%, respectively.

Tuchen emphasized that the equatorial thermocline, a vital layer for the El Niño–Southern Oscillation (ENSO), has steepened considerably. This steepening may reduce ENSO amplitude in the eastern Pacific while potentially leading to more frequent central Pacific El Niño events, thereby altering climate patterns.

The study offers a benchmark for improving climate models, which have historically struggled to represent the trends in Pacific circulation and sea surface temperatures accurately. The researchers believe their findings could enhance the predictability of ENSO events and their associated weather impacts.

Overall, this research underscores the importance of understanding the changes in ocean circulation and their implications for climate variability, particularly for regions like the United States that are influenced by ENSO-driven climate shifts.