Four decades of intensifying Southern Ocean swells along the Pacific coast of the Americas.

Abstract

Swells generated in the Southern Ocean regularly impact the Pacific coasts of the Americas, with the most energetic events causing severe infrastructure damage, coastal flooding, and loss of life. This study presents a detailed, comprehensive analysis of these high-energy swells along this coastline, characterizing their primary characteristics and examining their variability across multiple timescales. These swells occur most frequently during austral winter, with a considerable proportion also occurring in austral spring and autumn. The Southern Annular Mode exerts a strong influence, with its positive phase (SAM + ) being associated with more energetic swells. Significant positive trends in wave height, power, and occurrence rate along much of the studied coastline in recent decades highlight the increasing risk posed by these swell events. Our findings offer valuable insights for enhancing coastal resilience and informing effective risk management strategies in response to this coastal hazard.