A Global View on the Wind Sea and Swell Climate and Variability from ERA-40

TLDR

The study presents a detailed global climatology of wind‑sea and swell parameters from the 45‑year ERA‑40 reanalysis and investigates the spatial pattern of swell dominance in ocean wave fields. Using ERA‑40 wave reanalysis, the authors analyze interannual variability of wind‑sea and swell significant wave heights and their relationship to resultant heights across the Pacific, Atlantic, and Indian Oceans. Statistical analysis shows that the global ocean is dominated by swell waves, with distinct variability modes between wind‑sea and swell—especially in the Pacific and Atlantic—alongside a strong north–south swell propagation in the Atlantic during Northern Hemisphere winter and significant secular increases in wind‑sea and swell heights in the North Pacific and North Atlantic.

Abstract

Abstract In this paper a detailed global climatology of wind-sea and swell parameters, based on the 45-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) wave reanalysis is presented. The spatial pattern of the swell dominance of the earth’s oceans, in terms of the wave field energy balance and wave field characteristics, is also investigated. Statistical analysis shows that the global ocean is strongly dominated by swell waves. The interannual variability of the wind-sea and swell significant wave heights, and how they are related to the resultant significant wave height, is analyzed over the Pacific, Atlantic, and Indian Oceans. The leading modes of variability of wind sea and swell demonstrate noticeable differences, particularly in the Pacific and Atlantic Oceans. During the Northern Hemisphere winter, a strong north–south swell propagation pattern is observed in the Atlantic Ocean. Statistically significant secular increases in the wind-sea and swell significant wave heights are found in the North Pacific and North Atlantic Oceans.