Subtle influence of the Atlantic Meridional Overturning Circulation (AMOC) on seasonal sea surface temperature (SST) hindcast skill in the North Atlantic

Abstract. We investigate the impact of strength Atlantic Meridional Overturning Circulation (AMOC) at 26∘ N on prediction North sea surface temperature anomalies (SSTAs) a season ahead. test dependence temperate (SST) predictive skill in initialised hindcasts phase AMOC 26∘N, invoking seesaw mechanism driven by fluctuations, with positive SSTAs north and negative south after strong vice versa. use simulations MPI-ESM-MR (where MR is mixed resolution) seasonal system. First, we an assimilation experiment between 1979–2014 to confirm that leads SSTA dipole pattern tropical subtropical Atlantic, strongest fingerprints 2–4 months. Going beyond previous studies, find fingerprint has sensitive length observational window used, i.e. stronger over last decade than for entire time series back 1979. then set ensemble hindcast 30 members, starting each February, May, August November 1982 2014. compare changes composites based month prior start date without considering subtle influence SST skill. higher 2–4-month lead June–July–August (JJA) May dates full period. In other regions seasons, negligible predictions due atmospheric influence, calling caution when such mechanism. Our method shows that, following phases, summer subtropics increases significantly compared weak phases. This suggests assessment ahead eye should be kept initial state.