The North Atlantic Oscillation and the latitude of the Gulf Stream

The physical processes determining the path of the Gulf Stream as it leaves the continental shelf of the USA are complex and involved. Understanding these processes is important to global climate studies because the Gulf Stream plays a major roˆ le in the distribution of heat in the northern hemisphere. Here we show that during the last 3 decades, the latitude of the Gulf Stream has been clearly correlated with the North Atlantic Oscillation (NAO); high values of the NAO index, which correspond to stronger westerly and trade winds, favouring more northerly paths of the Stream about 2 years later. The time-delay may be associated with the adjustment time of this part of the ocean circulation. If allowance is made for persistence of the Gulf Stream position from one year to the next, more than half the interannual variation in the position can be predicted.