Integrated Supplementary Synthesis: Two-Timescale SST and SSH Evidence for a Delayed Gulf Stream–Kuroshio Extension Linkage via a Northern Hemisphere Atmospheric Bridge (1993–2024)

This supplementary synthesis integrates two-timescale observational evidence for a delayed Gulf Stream–Kuroshio Extension (GS–KE) linkage over 1993–2024. It combines lagged SST diagnostics with satellite altimetry–based sea surface height (SSH/SLA) analyses to assess the consistency of a proposed Northern Hemisphere atmospheric-bridge mechanism and subsequent oceanic adjustment. Results highlight (i) an asymmetric GS-leading relationship in SST with multi-year delay and winter enhancement, and (ii) a delayed, spatially coherent SSH response consistent with large-scale gyre adjustment and westward-propagating signals toward the KE region. The document is intended as supporting material for the companion preprint and as a foundation for follow-up mechanistic analyses.