Influence of Eastern Upwelling systems on marine heatwaves occurrence

Abstract Marine heatwaves (MHWs) are a central topic of research due to their extensive implications to marine fauna and flora. As far as we know, this is the first study focused on the occurrence of MHWs in the Eastern Boundary Upwelling systems (EBUs). For that purpose, trends in Sea Surface Temperature (SST) and in the number of MHW days were calculated to assess the different occurrence of MHWs nearshore and offshore using data from the NOAA OISST ¼ from 1982 to 2018. Benguela, Canary, Chile, Peru and California EBUs show lower trends in the number of MHW days near the coast (0.61, 6.70, −7.43, −9.74 and 1.09 days year−1 decade−1, respectively) than in the adjacent ocean unaffected by upwelling events (8.62, 12.35, −0.47, −9.39 and 9.99 days year−1 decade−1, respectively). This suggests that upwelling can moderate the occurrence of MHWs compared with the adjacent ocean.