The impact of sea surface temperature bias on equatorial Atlantic interannual variability in partially coupled model experiments

Abstract

We examine the impact of sea surface temperature (SST) bias on interannual variability during boreal summer over the equatorial Atlantic using two suites of partially coupled model (PCM) experiments with and without surface heat flux correction. In the experiments, surface wind stress anomalies are specified from observations while the thermodynamic coupling between the atmospheric and oceanic components is still active as in the fully coupled model. The results show that the PCM can capture around 50% of the observed variability associated with the Atlantic Niño from 1958 to 2013, but only when the bias is substantially reduced using heat flux correction, with no skill otherwise. We further show that ocean dynamics explain a large part of the SST variability in the eastern equatorial Atlantic in both observations (50-60%) and the PCM experiments (50-70%) with heat flux correction, implying that the seasonal predictability potential may be higher than currently thought. Key Points SST bias corrupts the simulation of equatorial Atlantic SST variability Fifty percent of Atlantic Nino is captured by a flux-corrected model driven by real winds Only a flux-corrected model captures the observed role of ocean dynamics.