| Summary: | Recent studies have linked interannual sea level variability and extreme events along the US northeast coast (NEC) to the North Atlantic Oscillation (NAO), a natural internal climate mode that prevails in the North Atlantic Ocean. The correlation between the NAO index and coastal sea level north of Cape Hatteras was weak from the 1960s to the mid-1980s but has markedly increased since ~1987. Causes for the decadal shift remain unknown. Yet understanding the abrupt change is vital for decadal sea level prediction and essential for risk management. Here we use a robust method, Bayesian Dynamic Linear Modeling (DLM), to explore the non-stationary NAO impact on NEC sea level. The results show that a spatial pattern change of NAO-related winds near the NEC is a major cause of the NAO-sea level relationship shift. A new index using regional sea level pressure is developed which is a significantly better predictor of NEC sea level than is the NAO and is strongly linked to the intensity of westerly winds near the NEC. These results point to the vital importance of monitoring regional changes of wind and sea level pressure patterns, rather than the NAO index alone, to achieve more accurate predictions of sea level change along the NEC.
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