Impact of model’s resolution on the sea surface temperature climate change signal in the Southeastern Tropical Atlantic

In this paper we study the influence of atmospheric and oceanic resolutions on the sea surface temperature (SST) under climate change and the related mechanisms. To this end, a set of historical period and future simulations in which two different atmospheric resolutions are combined with two different oceanic resolutions, one of them eddy-permitting, are used. We found that the magnitude of the warming is more dependent on atmospheric resolution, while the influence of oceanic resolution is stronger on the spatial pattern of SST changes, leading to the enhancement of the climate change signal in coastal regions in the higher resolution configuration. The mechanisms related to these changes involve both the atmosphere and the ocean, with the latter playing the main role. We found that changes in upwelling are the primary drivers of SST changes in regions close to the coast, and these changes in SST exhibit a clear seasonal pattern, precisely associated with the marked seasonality of the Benguela upwelling system. The radiative and turbulent fluxes adjust to the increase of greenhouse gases and are also influenced by the resolution and SST patterns. Additionally, the net longwave fluxes into the ocean increase, while the shortwave fluxes decrease due to the formation of low clouds.