Impacts of the North Atlantic Oscillation on sea surface temperature on the Northeast US Continental Shelf

Abstract

The North Atlantic Oscillation (NAO) is the dominant large-scale atmospheric oscillation in the North Atlantic and has profound effects on water temperatures in the North Atlantic. In this paper we diagnosed the effects of the NAO on sea surface temperature (SST) in the Northeast US Continental Shelf (NES). Waters in the Gulf of Maine (GOM) originate primarily from Scotian Shelf Water (SSW) at the surface and Labrador Slope Water (LSW) and Warm Slope Water (WSW) at depth through the Northeast Channel. By using a high-resolution SST dataset, we found that the correlation between the NAO and annual mean SST in the GOM is significant and negative at lag of four years. Further spatial correlation analysis shows that the NAO influences SST in the GOM primarily through advection of SSW or shelf water at the surface from the Labrador Sea. Cross-correlation analysis was also applied between the NAO and SSTs in other subregions of the NES (Georges Bank, Southern New England, and Mid-Atlantic Bight), but no statistically significant relationships were found at any lags. Different from temperature at depth in the GOM that is positively influenced by the NAO with a lag of two years, we concluded that the NAO has a significant negative effect on SST in the GOM four years later, while its effects on SSTs in the other three subregions of the NES are negligible. The four-year lagged relationship we found between the NAO and annual mean SST in the GOM provides a robust empirical method to predict the effect of the NAO on annual mean SST in the GOM four years in advance.