LAUSR

The Benguela Upwelling System (BUS) is the most productive of all eastern boundary upwelling ecosystems and it hosts a well‐developed oxygen minimum zone. As such, the BUS is a potential hotspot for production of N2O, a potent greenhouse gas derived from microbially driven decay of sinking organic matter. Yet, the extent at which near‐surface waters emit N2O to the atmosphere in the BUS is highly uncertain. Here we present the first high‐resolution surface measurements of N2O across the northern part of the BUS (nBUS). We found strong gradients with a threefold increase in N2O concentrations near the coast as compared with open ocean waters. Our observations show enhanced sea‐to‐air fluxes of N2O (up to 1.67 nmol m−2 s−1) in association with local upwelling cells. Based on our data we suggest that the nBUS can account for 13% of the total coastal upwelling source of N2O to the atmosphere.