Abstract
Temperature and salinity, derived from over 10 000 Argo profiles, are combined with 20 years of eddy trajectories and absolute dynamic topography maps to characterise the vertical structure of mesoscale eddies within the Azores Current corridor (AzCCo) from the surface to 1500 dbar. From east to west, our statistics reveal an intensification of anomaly maxima (from ∼ 0.5 °C and 0.1 to above ∼ 1.5 °C and 0.2 in salinity) and a deepening of their core location in the water column (from ∼ 250 to ∼ 750 dbar) for both anticyclones and cyclones. Anticyclones are characterised by a relatively depth-uniform structure, exhibiting warm, salty cores, while cyclones are more vertically structured, with a well-defined subsurface maximum featuring cold, fresh cores along the AzCCo. These zonal differences are associated with the origins of the sampled eddies and their dynamical properties on either side of the Mid-Atlantic Ridge (MAR). In the western region, eddies are more strongly influenced by remotely generated structures associated with Gulf Stream branches, contributing to higher anomaly amplitudes. To investigate the mechanisms responsible for these anomalies, an isopycnal decomposition of temperature and salinity anomalies is applied, separating them into two components: heave (HEV), associated with vertical deflections of isopycnal surfaces, and spice (SPI), representing variations along isopycnal surfaces. These components are linked to two main eddy transport mechanisms: eddy pumping and eddy trapping. HEV dominates the resulting vertical structures of temperature and salinity within the water column, indicating that most eddy-induced anomalies originate from eddy pumping, manifested as deflections of the isopycnal surfaces. This mechanism produces warmer, saltier anomalies within anticyclonic eddies due to downwelling of the isopycnal surfaces and colder, fresher anomalies within cyclonic eddies due to upwelling of the same surfaces. SPI exhibits higher values within the upper ∼ 250 dbar to the east of the MAR, reflecting the tendency of surface eddies to trap different water masses. Finally, absolute values of isopycnal vertical displacement above 50 dbar, from the surface to the 1500 dbar level, demonstrate the significant impact of these mesoscale structures throughout the water column. Overall, these results highlight the AzCCo as a vertically driven mesoscale regime in which eddies primarily redistribute thermohaline properties through isopycnal displacement rather than lateral transport.