Detailed 2-D imaging of the Mediterranean outflow and meddies off W Iberia from multichannel seismic data

The mesoscale structures were imaged via reflections from oceanic fine structures of scale 30 m or less. We compare the characteristics of observed reflections with known mechanisms of fine-structure production. Most of the observed reflections are consistent with internal waves and thermohaline intrusions as previously hypothesized. We postulate a new mechanism to explain the formation of the steeply sloping reflections that outline the meddy and other features, involving frontogenetic isopycnal advection, formation of thermohaline intrusions, and tilting of the intrusive layers by mesoscale shear flows. The imaging technique therefore shows the relationship between mesoscale features and the fine-scale oceanographic phenomena associated with mixing, including steeply-sloped structures that would otherwise not be tracked using CTD profiles alone.