Extreme Compound Events in the Equatorial and South Atlantic

The impacts of marine heatwaves (MHWs) on marine ecosystems can be amplified when combined with other extreme events. Here, we investigate the temporal-spatial distribution of compound events of MHW, high acidity and low chlorophyll in the equatorial and South Atlantic, using observation-based datasets and reanalysis products. We show that the frequency and intensity of these triple compound events have increased dramatically over the past two decades, peaking in the most recent years. We analysed the drivers of triple compound events for six regions and found that, for the Angola Front and Brazil-Malvinas Confluence regions, these events are associated with a poleward shift of the fronts. In the Agulhas Leakage region, an increase in warmer waters entering from the Indian Ocean leads to compound extremes. In the western equatorial and subtropical Atlantic, they are caused by changes in the air-sea heat fluxes, while in the eastern equatorial by a weakening of upwelling. In addition, triple compound events are widespread over the South Atlantic during El Niño events. This is important because MHWs can be predicted when they are associated with ENSO.