Shelf turbulence-driven mixing of the Arabian Gulf outflow: Impacts on the Arabian Sea Oxygen Minimum Zone and marine ecosystem

Multiple long-standing gaps in our understanding of the Arabian/Persian Gulf Outflow (AGO) hinder a detailed characterisation of the AGO as well as an assessment of the impact on the Arabian Sea. These gaps include a lack of systematic AGO thickness budgets, missing observational evidence for detachment thresholds, poorly constrained downstream mixing pathways, insufficient mapping of bathymetric controls on the outflow, sparse data on along-path oxygen modification, and no prior linkage between AGO physical structure and ecosystem, e.g., benthic zonation. Here, we present new high-resolution observational mapping of the AGO thickness, attachment/detachment behaviour, lateral mixing, and benthic changes on the seafloor in the Gulf of Oman, at the mouth of the Arabian Sea. We present seasonal CTD data, combined with high-resolution bathymetry and ROV observations. These data allow us to (1) resolve AGO thickness variability along the margin, (2) identify seafloor attachment and detachment zones, (3) map fine-scale oxygen and pH modification of the outflow, and (4) document changes in marine benthic zonation consistent with AGO boundary-layer structure.