Recurrent Oceanic Circulation Patterns in the Gulf of Mexico

Recent observational studies indicate dominant circulation patterns in the deep Gulf of Mexico (GoM), induced by interactions between the Loop Current Eddies (LCEs) and the topography, as well as a coupling between the upper layer (< 1000 m) and the lower layer (>1500 m) circulation as an eddy propagates towards the western basin. In this study, we use isopycnal layer thickness data produced by a 20-year free-run numerical experiment configured for the GoM using HYCOM, and the Complex Empirical Orthogonal Functions (CEOFs) techniche to estimate the more recurrent oceanic circulation patterns in the upper layer of the GoM and examine the physical processes responsible for their respective coupling with the lower layer. The results show a major mode of coupled variability over the Loop Current’s extension and retraction region that manifests as deep eddies, among other features, in the lower layer. Following minor modes explain variability apparently related with the shedding, westward propagation and fate of LCEs. Composites of layer thickness anomalies for the first 5 modes of coupled variability (> 70% of explained variance) are constructed for LCE shedding and westward propagation events and analyzed in order to verify the response of the lower layer.