Main covariability patterns between the Loop Current and the flow through the Yucatan Channel from altimetry and sustained moored observations

Abstract

The Loop Current (\textbf{LC}) dominates circulation in the Gulf of Mexico, yet how its surface structure relates to Yucatan Channel flow remains incompletely understood. We apply maximum covariance analysis to altimetry-derived geostrophic speed over the LC domain and Canek velocity observations across the Yucatan Channel during 2011--2023. The leading mode explains 84\% of the squared covariance and links lateral displacements of the Yucatan Current core to the LC extension--retraction cycle. Its Yucatan principal component correlates strongly with core longitude (\(r=0.90\)) but weakly with total Channel transport (\(r=0.32\)), and has coherent counterparts in the deep Yucatan flow and downstream Florida observations, neither of which entered the decomposition. A second mode explains 11\% and links Yucatan Current intensification and core geometry to cyclonic meandering along the western Channel and contrasting LC pathways. Time-normalized composites show these configurations develop over a median of 35 days, with negative events preceded by recurrent anticyclonic circulation in the northwestern Caribbean. Lagged correlations computed independently of the decomposition show that core position remains coherently associated with the LC pathway when leading by 20--40 days, whereas transport alone shows weaker relationships. A diagnostic linear reconstruction from the full Yucatan and Florida sections recovers broad contemporaneous LC surface features over an independently withheld interval. The spatial structure of the boundary flow, particularly current position and geometry, therefore carries more information about LC state than total transport alone, highlighting the value of sustained gateway observations for monitoring and state estimation.