Understanding Atlantic multi-decadal variability prediction skill



[1] Initialized and uninitialized decadal retrospective forecasts (re-forecasts) are used to assess the key regions providing multi-year prediction skill of the Atlantic multi-decadal sea surface temperature variability (AMV) and to address the relative roles of the initial conditions and external forcing on this skill. The results show that there is a decay in the AMV skill with forecast time, which is likely to be driven by skill degradation in predicting the AMV subpolar branch due to the lack of skill in predicting the subtropical branch. An important role of the varying radiative forcing in the AMV-related prediction skill is found over the Labrador and Irminger deep convection regions. Initialized predictions show the largest impact on the improvement in the AMV-related skill over the area where the Atlantic subpolar gyre operates. Initialization appears also to correct an unrealistic anticorrelation between the AMV phase and the Gulf Stream found in the uninitialized re-forecasts.