Interannual to decadal Gulf Stream variability in an eddy-resolving ocean model

Meridional shifts of the Gulf Stream (GS) jet on interannual to decadal timescales and the corresponding sea surface temperature (SST) changes are investigated using a hindcast output of a near global eddy-resolving ocean model from 1960 to 2003. The simulated variability in the GS jet shows good agreement with subsurface and satellite observations, and is related to the 2-yr leading atmospheric fluctuations characterized by the North Atlantic Oscillation (NAO). The lagged response of the GS jet to the atmospheric variations is attributed to the westward propagation of the meander, which has a wavelength of about 4000 km with a phase speed of about 2.8 cm/s. The propagation direction and phase speed of the long-wavelength meander can be explained by the thin-jet theory. The meanders are likely induced by wind stress curl fluctuations over the central North Atlantic. Associated with the northward (southward) shift of the jet is SST warming (cooling) around and north of the jet. The former warming has a deep and meridionally narrow subsurface structure, consistent with the northward shift of the jet. Our numerical results suggest that the GS jet brings the atmospheric signals from the central to the western North Atlantic, and the resultant meridional shift of the jet induces the notable SST changes around the GS.