Indian Ocean anomaly challenges Ekman’s ocean current theory

A study published in Science Advances has identified a significant anomaly in Vagn Walfrid Ekman’s widely accepted theory of wind-driven ocean currents. Conducted by a team of researchers from NOAA, the Indian National Center for Ocean Information Services and the University of Zagreb, the study focused on the Bay of Bengal in the Indian Ocean. Several years of data from a buoy stationed off the east coast of India were examined, showing that ocean currents in this area deflect to the left, contradicting the theory’s predictions for the Northern Hemisphere.

Ekman’s theory and its long-lasting influence

The Ekman theory, developed in 1905 by Swedish oceanographer Vagn Walfrid Ekman, states that surface ocean currents in the Northern Hemisphere are deflected 45 degrees to the right of the wind direction due to the Coriolis force. Successive layers below the surface show similar patterns and form the Ekman spiral. This mechanism, while robust, assumes idealized conditions, including uniform ocean depth and density. Variations such as those observed in the Bay of Bengal highlight its limitations.

Findings from the Bay of Bengal

According to the studyData collected over several years showed that the current in the Bay of Bengal veered to the left despite prevailing winds, defying Ekman’s predictions. This anomaly underlines the need to reassess assumptions about global oceanic patterns. The researchers suggested that local factors, including unique regional wind patterns and oceanic dynamics, could play an important role.

Implications for climate models

A statement from the researchers noted that the findings could influence future climate modeling efforts. If exceptions to Ekman’s theory exist in the Bay of Bengal, others could also occur worldwide, underscoring the need for more detailed oceanographic research. Discussions have also highlighted the potential deployment of a NASA satellite system to comprehensively monitor wind and surface currents.

This study has drawn attention to gaps in the understanding of wind-driven currents, and highlights the importance of revising established models as global warming continues to influence the behavior of the oceans.