N ₂ O Emissions From the Eastern Tropical Indian Ocean

Abstract Nitrous oxide (N 2 O) is a potent greenhouse gas and major stratospheric ozone‐depleting compound. While 30% of global N 2 O emissions are attributed to the oceans, there are still large uncertainties partly due to sparse data coverage. The eastern tropical Indian Ocean is an under‐sampled area which potentially acts as a source of atmospheric N 2 O. In this study, we present the most comprehensive, high‐resolution survey of surface water N 2 O concentrations and air‐sea fluxes in the region to date, spanning the equatorial area as well as open and near‐coastal waters of Bay of Bengal. We show significant spatial and temporal variability in N 2 O concentrations driven by upwelling, riverine inputs and monsoonal influence. The northern Bay of Bengal was identified as a hotspot for N 2 O emissions, while salinity‐driven stratification limited emissions in other areas. Overall, the Bay of Bengal contributes 0.9%–1.5% to global oceanic N 2 O emissions.