Spatiotemporal characteristics of Eddy–Eddy interactions east of the Drake Passage

Eddy–eddy interactions, ubiquitous across the global ocean, play a significant role in eddy evolution. Utilizing satellite altimetry data from 1993 to 2023, coupled with the angular momentum eddy detection and tracking algorithm (AMEDA), this study investigates eddy–eddy interactions east of the Drake Passage. These interactions are predominantly concentrated within the western and southern Argentine Basin and the Scotia Sea. In the region, the number of eddy–eddy interactions is higher during summer and lower during winter in the Southern Hemisphere. On seasonal timescales, both eddy intensity and the eddy Rossby number are negatively correlated with eddy number and the number of eddy–eddy interactions. This indicates that when the eddy intensity is greater, the likelihood of interaction is lower, which may be related to eddy stability. Quantitatively, merged eddies attain 193.7% of the mean area and 134.1% of the mean azimuthal velocity of their pre-merger counterparts; conversely, pre-split eddies reach 207.0% of the area and 137.7% of the azimuthal velocity averaged over the two post-split eddies. Spatially, regions with a high number of eddy–eddy interactions coincide with areas characterized by high topographic roughness and are also characterized by frequent eddy generation and dissipation. Notably, in the western Argentine Basin, interacting eddies propagate at larger angles relative to the local isobaths, whereas non-interacting eddies primarily propagate along the isobaths. These findings highlight the significant roles of both eddy intensity and topographic roughness in modulating eddy–eddy interactions.