Wind Stress‐Induced Multiyear Predictability of Annual Extratropical North Atlantic Sea Surface Temperature Anomalies.

Long‐term predictability of the North Atlantic sea surface temperature (SST) is commonly attributed to buoyancy‐forced changes of the Atlantic Meridional Overturning Circulation. Here we investigate the role of surface wind stress forcing in decadal hindcasts as another source of extratropical North Atlantic SST predictability. For this purpose, a global climate model is forced by reanalysis (ERA‐interim) wind stress anomalies over the period 1979–2017. The simulated climate states serve as initial conditions for decadal hindcasts. Significant skill in predicting detrended observed annual SST anomalies is observed over the extratropical central North Atlantic with anomaly correlation coefficients exceeding 0.6 at lead times of 4 to 7 yrs. The skill is insensitive to the calendar month of initialization and primarily linked to upper ocean heat content anomalies that lead anomalous SSTs by several years. Plain Language Summary: Certain aspects of the climate can be predicted several years in advance. This is primarily due to the slow components of the climate system, especially the ocean, which can influence the atmosphere on time scales of years to decades. It is thus essential to start long‐term climate forecasts from a realistic ocean state. However, ocean observations, especially subsurface data, are limited. Hence, predictions are often only based on surface observations. Here we demonstrate that the use of observed surface wind stress yields skillful predictions of the sea surface temperature (SST) over the extratropical North Atlantic at lead times of up to about 7 yrs. This is because the ocean circulation responds to the wind stress changes, which generate subsurface temperature anomalies that affect the surface with a time delay. These results may not only be of scientific but also of public and economic interest, because extratropical North Atlantic SST is thought to influence mean climate and extreme weather events over the adjacent continents. Key Points: Wind stress initialization yields skillful multiyear hindcasts of annual extratropical North Atlantic sea surface temperature anomaliesThe skill is essentially insensitive to the initialization calendar monthThe skill is linked to an upper ocean heat content anomaly that leads anomalous sea surface temperatures by several years [ABSTRACT FROM AUTHOR]