Western Boundary Currents Affect Local Climate Variability, Claims New Study

A study led by atmospheric scientists at Colorado State University reveals that western boundary currents, powerful ocean currents along coastlines, have a greater impact on local climate variability than previously recognised. Researchers James Larson, David Thompson and James Hurrell shared their findings in Nature. They showed how these currents influence temperature and atmospheric patterns in ways that could refine climate models and improve weather forecasting.

Western boundary currents, including the Gulf Stream off North America and the Kuroshio Current near Japan, are known for transporting large amounts of warm water from tropical regions to higher latitudes. This movement affects wind, precipitation and overall climate patterns across vast areas. But the study takes a deeper look. It specifically examies how these currents affect local weather variations rather than just broader climate averages.

High-Resolution Data Shows Links Between Ocean and Atmosphere

The research, which was published on Phys.org, reveals that using high-resolution satellite data and numerical modelling, the team investigated how changes in sea surface temperatures (SSTs) over western boundary currents correlate with atmospheric circulation and precipitation. Their month-by-month analysis tracked how SST variations relate to shifts in air circulation in the lower atmosphere, particularly around these major currents. They discovered that fluctuations in SSTs directly influence atmospheric behaviours, such as vertical air movement and rainfall patterns.

For example, regions with greater SST changes over western boundary currents also showed significant shifts in local air circulation and precipitation. This finding indicates that these currents not only carry warm water but also drive complex weather dynamics in nearby areas, creating variability in rainfall and atmospheric conditions that can impact local climates in both hemispheres.

Implications for Climate Models and Forecasting

The study's insights suggest that existing weather and climate models might need adjustment to account for the influence of these currents on local climate variability. Larson and his team highlight a mechanism through which ocean conditions affect the atmosphere in a way that hasn't been fully incorporated in current forecasting models.

By showing the close connection between SSTs over boundary currents and local weather patterns, the researchers' work may lead to more precise forecasts for regions influenced by these oceanic pathways. With improved modelling, communities situated near major boundary currents could benefit from better predictions of weather changes driven by ocean temperatures.