North Atlantic Oscillation (NAO) Climate Index Hidden in Ocean Generated Secondary Microseisms

With the role of surface winds in the generation of ocean waves, secondary microseisms induced by ocean wave-wave interactions represent a unique interconnection between the solid Earth, the ocean and global atmospheric circulation patterns. In this study, temporal changes in the ocean generated seismic wavefield in Northeast Atlantic are monitored offshore West of Ireland using ocean bottom seismometers located on top of a thick sedimentary basin. Comparisons with numerical seismic simulations and ocean wave model hindcast data suggest those variations are correlated with changing patterns in ocean wave-wave interactions closely linked to secondary microseism generation areas. Here we show how those changes, accentuated by the specific structure of the Irish offshore margin, reveal the signature of the North Atlantic Oscillation (NAO) in the Earth's background seismic wavefield. In the North Atlantic, secondary microseism sources likely fluctuate with the changing storm track in response to variations in the NAO.

Automated summary

This study reveals the impact of ocean wave-wave interactions on the seismic wavefield generated offshore West of Ireland in the Northeast Atlantic. The variations observed are closely correlated with changing patterns in secondary microseism generation areas, potentially influenced by the North Atlantic Oscillation.