North Atlantic Subpolar Gyre Provides Downstream Ocean Predictability

Abstract It has been hypothesized that North Atlantic subpolar gyre (SPG) exerts substantial influence on climate predictability. However, a clear identification of the downstream impact of SPG variations is still lacking. Using MPI-ESM-LR1.2 decadal prediction system, we show that along the Atlantic water pathway, a dynamical link to the SPG causes salinity to be considerably better predicted than temperature. By modulating slow northward ocean propagation, the memory of SPG variations in subsurface salinity causes salinity to be skillfully predicted up to 8 years ahead. In contrast, SPG loses influence on temperature before Atlantic water penetrates into the Nordic Seas, where temperature is only predicted up to 2 years ahead. This study identifies the key role of SPG signals in downstream prediction and highlights how SPG signals determine prediction time scales for different quantities, opening the door for investigating multiple quantities in the subarctic for earth system prediction research.