In this study, the ENSO teleconnection with the tropical North Atlantic (TNA) sea surface temperatures
(SSTs) in boreal spring is analyzed in ocean–atmosphere coupled global circulation models. To assess the role played by
horizontal resolution of models on this teleconnection, we used a multimodel dataset that is the first to combine models with
both low and high resolution. The TNA response to ENSO projects onto the most significant SST mode of the tropical
Atlantic at interannual time scales, the Atlantic meridional mode (AMM). Its evolution is primarily driven by the wind–
evaporation–SST (WES) feedback, which in turn is based on the development of an initial SST gradient. This study
examines and quantifies the relative contribution of a dynamic-related (upwelling) and a thermodynamic-related
(evaporation) process in triggering this gradient in the case of the ENSO–TNA teleconnection. While no major
contribution is found with the evaporation, a consistent contribution from the coastal upwelling off northwest Africa is
identified. This contribution is enhanced in high-resolution models and highlights the close link between the upwelling in
winter and the development of the AMM in spring. It is further shown that high-resolution models present a thinner and
more realistic ocean mixed layer within the upwelling area, which enhances the effect of surface winds on upwelling and
SSTs. As a consequence, high-resolution models are more sensitive than low-resolution models to surface wind errors,
thereby they do not ensure improved reliability or predictability of the TNA SST response to ENSO.
