The Impact of the Atlantic Multidecadal Oscillation on the Interannual Relationship Between the Storm Track and SST Over the North Atlantic in Spring

Abstract

ABSTRACT The present study shows that the intensity of the springtime Atlantic storm track (AST) is affected by sea surface temperature (SST) anomalies in the tropical northern Atlantic (TNA) region on an interannual time scale, and the AST intensity variation in turn induces the underlying SST anomalies in the following months using the reanalysis data. Moreover, the interannual relationship is modulated by the Atlantic Multidecadal Oscillation (AMO) on a decadal time scale. During the negative phase of the AMO, AST activity weakens when warm SST anomalies appear in the TNA region, while warm TNA SST anomalies during the positive phase of the AMO correspond to a weakening of AST activity in the northeast region of the climatological AST. Anomalous westerly winds, Eady growth rate (EGR), and baroclinic energy conversion (BCEC) associated with the TNA SST anomalies can be found upstream of the AST anomalies during both AMO phases. On the other hand, the AST intensity variation is closely related to the underlying SST in the following months, especially in the next month. During the positive phase of the AMO, both the upward surface net heat flux (Q net) and westerly wind anomalies related to the AST are more marked than those during the negative phase of the AMO. This results in significant negative and westward-extending SST anomalies over the extratropical North Atlantic. This study suggests that the ocean–atmosphere interaction processes associated with the springtime AST variability are modulated by the AMO.